This document describes the development of a label-free electrochemical protein sensor using perchloric acid doped polyaniline (PANI-PA). PANI-PA films were fabricated on glass substrates using in situ polymerization. The sensor detects changes in surface potential when proteins interact with the charged PANI-PA film, allowing for label-free potentiometric protein detection. The sensor was tested for its ability to detect lysozyme, bovine serum albumin, and thaumatin proteins. PANI-PA was found to have high conductivity even at neutral pH values, making it suitable for protein sensing under physiological conditions. The sensor has potential for integration into implantable biosensing systems and for recognizing specific protein-protein
Thermal stability, complexing behavior, and ionic transport ofSHALU KATARIA
This document describes a study on polymeric gel membranes composed of poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) polymer and an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The membranes were synthesized by solution casting and characterized using various techniques. It was found that the ionic liquid partly complexes with the PVdF-HFP polymer chains and partly remains dispersed. The ionic conductivity of the membranes increases with increasing ionic liquid content, reaching a maximum of 1.6 × 10−2 S·cm−1 for a membrane with 90% ionic liquid
The document describes using reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize novel block copolymers containing both a polyolefin block and a poly(styrene-co-maleic anhydride) block. Specifically, it details:
1) Using a commercially available polyolefin (Kraton L-1203) modified with a dithioester group to serve as a macroinitiator for RAFT polymerization and form the polyolefin block.
2) Conducting RAFT polymerizations of styrene and styrene-co-maleic anhydride using this macroinitiator and a small molecule RAFT agent to form the second block and yield polyolefin
This document summarizes a study investigating the initialization behavior of reversible addition-fragmentation chain transfer (RAFT)-mediated styrene-maleic anhydride copolymerizations using in situ 1H NMR spectroscopy. The results indicate specificity of addition of the RAFT agent leaving groups for either styrene or maleic anhydride. Analysis of the NMR spectra also showed that monomers are added individually, favoring the penultimate unit model of polymer propagation over other proposed mechanisms. Stereoselectivity was observed during monomer addition to the RAFT agent.
The document summarizes a study on the thermal degradation of three natural polymers: sodium hyaluronate, xanthan, and methylcellulose. Thermogravimetric analysis showed sodium hyaluronate and xanthan had lower thermal stability than methylcellulose. Kinetic parameters like activation energy were determined using the Ozawa and Freeman-Carroll methods, which suggested changes in degradation mechanism with mass loss. Activation energies from Freeman-Carroll were higher, accounting for thermal history effects. Infrared spectroscopy observed scission of side groups at low temperatures and backbone links at high temperatures, agreeing with kinetic parameters.
Influence of Tetra Alkyl Ammonium Cation and Temperature on Molecular Interac...IOSRJAC
Ultrasonic velocity (u), density (ρ), viscosity (η) and related acoustical parameters such as adiabatic compressibility (β), free energy (∆G), internal pressure (πi), relaxation time (τ) and acoustic impedance (z) have been computed using standard relation for tetra alkyl ammonium cation (Et4N + , Pr4N + , Bu4N + , and Pen4N + ) in binary liquid mixtures of 1, 4 - Dioxane and N, N – Dimethyl Formamide was prepared of 0.14M on different percentage compositions over the temperature range from 303.15K to 323.15K with the interval of 10K under room pressure to investigate inter - ionic interactions. The densities were measured by Magnetic Float Densitometer. Transport properties provide a deep and meaningful insight of various interactions taking place. It has been observed that the influence of small as well as large alkyl chain length of tetra alkyl ammonium cations (R4N + ), in terms of shape and ionic size with the DMF solvent in the presence of Dioxane, is helpful in investigating the molecular interactions, molecular rearrangement, molecular association etc
This document summarizes research on the effects of gamma irradiation on the viscoelastic properties of sodium alginate polysaccharides. The researchers found that:
1) Irradiating sodium alginate solutions decreased their apparent viscosity and consistency, suggesting the gamma rays broke down the macromolecular structure.
2) Higher irradiation doses and lower polysaccharide concentrations led to greater decreases in viscosity.
3) The non-Newtonian, pseudoplastic behavior of the solutions was maintained after irradiation, though trends moved toward Newtonian behavior at higher doses.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
This document describes a study on the use of PtCo and PtNi nanoparticles supported on graphitic mesoporous carbon (GMC) as electrocatalysts for the electro-oxidation of methanol. The electrocatalysts were prepared using a sequential impregnation reduction method and characterized using various techniques. Their performance for methanol oxidation was evaluated using cyclic voltammetry. The results showed that PtCo/GMC had the highest mass activity and CO tolerance, followed by PtNi/GMC, due to the high metal nanoparticle dispersion and GMC support, which facilitated CO oxidation through a bifunctional mechanism.
Thermal stability, complexing behavior, and ionic transport ofSHALU KATARIA
This document describes a study on polymeric gel membranes composed of poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) polymer and an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The membranes were synthesized by solution casting and characterized using various techniques. It was found that the ionic liquid partly complexes with the PVdF-HFP polymer chains and partly remains dispersed. The ionic conductivity of the membranes increases with increasing ionic liquid content, reaching a maximum of 1.6 × 10−2 S·cm−1 for a membrane with 90% ionic liquid
The document describes using reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize novel block copolymers containing both a polyolefin block and a poly(styrene-co-maleic anhydride) block. Specifically, it details:
1) Using a commercially available polyolefin (Kraton L-1203) modified with a dithioester group to serve as a macroinitiator for RAFT polymerization and form the polyolefin block.
2) Conducting RAFT polymerizations of styrene and styrene-co-maleic anhydride using this macroinitiator and a small molecule RAFT agent to form the second block and yield polyolefin
This document summarizes a study investigating the initialization behavior of reversible addition-fragmentation chain transfer (RAFT)-mediated styrene-maleic anhydride copolymerizations using in situ 1H NMR spectroscopy. The results indicate specificity of addition of the RAFT agent leaving groups for either styrene or maleic anhydride. Analysis of the NMR spectra also showed that monomers are added individually, favoring the penultimate unit model of polymer propagation over other proposed mechanisms. Stereoselectivity was observed during monomer addition to the RAFT agent.
The document summarizes a study on the thermal degradation of three natural polymers: sodium hyaluronate, xanthan, and methylcellulose. Thermogravimetric analysis showed sodium hyaluronate and xanthan had lower thermal stability than methylcellulose. Kinetic parameters like activation energy were determined using the Ozawa and Freeman-Carroll methods, which suggested changes in degradation mechanism with mass loss. Activation energies from Freeman-Carroll were higher, accounting for thermal history effects. Infrared spectroscopy observed scission of side groups at low temperatures and backbone links at high temperatures, agreeing with kinetic parameters.
Influence of Tetra Alkyl Ammonium Cation and Temperature on Molecular Interac...IOSRJAC
Ultrasonic velocity (u), density (ρ), viscosity (η) and related acoustical parameters such as adiabatic compressibility (β), free energy (∆G), internal pressure (πi), relaxation time (τ) and acoustic impedance (z) have been computed using standard relation for tetra alkyl ammonium cation (Et4N + , Pr4N + , Bu4N + , and Pen4N + ) in binary liquid mixtures of 1, 4 - Dioxane and N, N – Dimethyl Formamide was prepared of 0.14M on different percentage compositions over the temperature range from 303.15K to 323.15K with the interval of 10K under room pressure to investigate inter - ionic interactions. The densities were measured by Magnetic Float Densitometer. Transport properties provide a deep and meaningful insight of various interactions taking place. It has been observed that the influence of small as well as large alkyl chain length of tetra alkyl ammonium cations (R4N + ), in terms of shape and ionic size with the DMF solvent in the presence of Dioxane, is helpful in investigating the molecular interactions, molecular rearrangement, molecular association etc
This document summarizes research on the effects of gamma irradiation on the viscoelastic properties of sodium alginate polysaccharides. The researchers found that:
1) Irradiating sodium alginate solutions decreased their apparent viscosity and consistency, suggesting the gamma rays broke down the macromolecular structure.
2) Higher irradiation doses and lower polysaccharide concentrations led to greater decreases in viscosity.
3) The non-Newtonian, pseudoplastic behavior of the solutions was maintained after irradiation, though trends moved toward Newtonian behavior at higher doses.
Dielectric Relaxation And Molecular Interaction Studies Of PEG With Non-Polar...IOSR Journals
This document discusses a study of the dielectric relaxation and molecular interactions of polyethylene glycol (PEG) with non-polar solvents like carbon tetrachloride, benzene, and 1,4-dioxane using time domain reflectometry technique. The complex dielectric permittivity was measured for PEG-solvent mixtures at different concentrations from 10 MHz to 30 GHz. Parameters like the static dielectric constant, relaxation time, Bruggeman factor, and Kirkwood correlation factors were determined. The results indicate that heteromolecular hydrogen bonding between PEG and the solvents significantly affects the dielectric properties of the mixtures.
This document describes a study on the use of PtCo and PtNi nanoparticles supported on graphitic mesoporous carbon (GMC) as electrocatalysts for the electro-oxidation of methanol. The electrocatalysts were prepared using a sequential impregnation reduction method and characterized using various techniques. Their performance for methanol oxidation was evaluated using cyclic voltammetry. The results showed that PtCo/GMC had the highest mass activity and CO tolerance, followed by PtNi/GMC, due to the high metal nanoparticle dispersion and GMC support, which facilitated CO oxidation through a bifunctional mechanism.
Effects of heat treatment on the catalytic activity and methanol tolerance of...sunidevi
This document summarizes a study on the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Carbon-supported platinum (Pt/C) and platinum alloy (Pt-Co/C, Pt-Cu/C, Pt-Fe/C, Pt-Ni/C) catalysts were subjected to heat treatments at different temperatures. X-ray diffraction, transmission electron microscopy, and electrochemical measurements were used to characterize the catalysts and evaluate their oxygen reduction reaction activity and methanol tolerance. The results showed that heat treatment improved catalytic activity by increasing particle size but the optimal temperature depended on the catalyst. Pt-Cu/C treated at 350°C showed the highest activity and
Crosslinked Microgels as Platform for Hydrolytic Catalysts Article pubs.acs.o...aaaa zzzz
This document describes the development of a new protocol for synthesizing crosslinked microgels via UV-initiated free radical polymerization of miniemulsions at ambient temperature or below. The microgels are formed from butyl acrylate, ethylene glycol dimethacrylate, and a catalyst-precursor ligand. The catalytic activity of the microgels is demonstrated through the hydrolysis of 4-methylumbelliferyl β-D-galactopyranoside. A correlation is observed between the crosslinking content of the microgels and their catalytic proficiency, with peak performance at 40 mol% crosslinking.
Visible Spectrophotometric Determination of Gemigliptin Using Charge Transfer...Ratnakaram Venkata Nadh
A visible spectrophotometric method was developed and validated for the determination of gemigliptin present in bulk drug and tablet formulation. It involves an indirect method of charge transfer complex formation in presence of NBS, metol and suphanilic acid. Gemigliptin was subjected to oxidation with excess amount of oxidant (NBS) and the unconsumed NBS oxidizes metol to give p-N-methylbenzoquinone monoamine (PNMM) which in turn forms a charge transfer complex with sulphanilic acid. Then validated the above developed method as per the current ICH guidelines. An excellent correlation coefficient (> 0.999) was found for the obtained regression equation
(y = –0.0302x + 0.928) in the range of 2.0–30.0 μg mL-1. The method was found to be simple and rapid because it does not involve any solvent extraction. The recovery levels of the drug were in the range 99.92 – 100.08.
The document summarizes a study that used a palladium catalyst to synthesize benzofuran through a Sonogashira coupling reaction between 5-iodovanillin and 3-methyl-3-butyne-2-ol. The reaction was carried out using various amounts of palladium acetate, triphenylphosphine, and solvent. NMR spectroscopy showed the product formed, though it was impure likely due to side reactions promoted by the copper co-catalyst. While the reaction showed good atom economy, the yields were relatively low at 7.45% maximum. Further optimization is needed to improve purity and yields.
OBC epoxidations paper - Queen Mary University LONDON UK - Thomas FollierThomas Follier
This document reports on a study of the catalytic activity of manganese complexes with two similar polyamine ligands (7 and 8) that differ by the presence of a secondary or tertiary nitrogen, in the epoxidation of styrene. Ligand 7 showed the highest activity with MnSO4 and H2O2, while ligand 8 was most effective with Mn(OTf)2, MnCl2, and Mn(ClO4)2 using peracetic acid. Kinetic analysis indicated the structural differences in the ligands lead to differences in the nature of the active species formed. Ligand 7 with MnSO4 produced the epoxide in 78% yield, while ligand 8 with Mn(OT
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...sunitha81
Poly (o-phenylenediamine) (PoPD) microrods were obtained by interfacial
polymerization using ferric chloride as oxidant and without any template or
functional dopant. Pt/PoPD nanocatalysts were prepared by the reduction of chloroplatinic
acid with sodium borohydride, and the composite catalysts formed were
characterized by X-ray diffraction and electrochemical methods. The nanocomposite
of Pt/PoPD microrods has been explored for their electro-catalytic performance
towards oxidation of methanol. The electro-catalytic activity of Pt/PoPD was
found to be much higher (current density 1.96 mA/cm2 at 0.70 V) in comparison to
Pt/Vulcan electrodes (the current density values of 1.56 mA/cm2 at 0.71 V) which
may be attributed to the microrod morphology of PoPD that facilitate the effective
dispersion of Pt particles and easier access of methanol towards the catalytic sites.
This document describes the development of a fluorescent probe for sensing thiamine (vitamin B1) based on arginine-functionalized graphene quantum dots (Arg-GQDs). Arg-GQDs were synthesized through a one-pot hydrothermal method using citric acid and arginine as carbon and nitrogen precursors. The Arg-GQDs exhibited strong blue fluorescence with a quantum yield of 28.3%. The fluorescence of the Arg-GQDs was selectively quenched by Ag+ ions and recovered upon addition of thiamine, providing the basis for a fluorescence "off-on" probe for thiamine. Central composite design and response surface methodology were used to optimize the detection conditions, including pH, time
A powerful and convenient reaction procedure for the C-N coupling reaction (the Buchwald-Hartwig reaction), yielding products of N-arylanilines and N-arylamines in both conventional heating and microwave irradiation has been reported. The protocol utilizes a stable and new supper ferromagnetic nanoparticle chelating N-heterocyclic dicarbene palladium(II) complex (Pd-NHC) as catalyst which helps/allows us to complete the reaction with only 0.002 mol% Pd producing high yield products. We also examined the reusability of the catalyst. It was found that the catalyst could be recovered by external magnetic field and reused for seven times without obvious loss in catalytic activity.
Technique that is used to elucidate mechanism of a reaction or in a metabolic pathway and in a cell. The labeling takes place by exchanging a specific atom with their isotope. The detecting of the isotopes in the product helps to understand the possible mechanism and the stereochemistry in this sequence of the reaction. The detection of the isotopic labels is dependent on the kind of isotope. Radioactive isotopes like 3H 14C are measured radiochemical. Stable isotopes like 2H and 13C are detected for example with NMR- and IR-spectroscopy.
Kristina Melnik & Stephanie Felten (Undergraduate Students)
University of Utah
2014
Whole Chain Electron Transport under Nitrogen Stress in Spirulina PlatensisIRJET Journal
1. The study examines the effect of nitrogen stress on whole chain electron transport in the cyanobacterium Spirulina platensis. Nitrogen stress is induced by incubating cells in growth medium containing reduced nitrate concentrations ranging from 40-80 μM.
2. Nitrogen stress results in a time-dependent inhibition of whole chain electron transport. Incubation for 24 hours in 60 μM nitrate medium causes a 44% loss, increasing to 54% after 48 hours. Reducing nitrate to 40 μM causes a 52% loss after 24 hours.
3. Photosystem II activity is more sensitive to nitrogen stress than Photosystem I activity. Nitrogen stress causes concentration-dependent inhibition of Photosystem II electron transport
Degradation of poly-L-lactide. Part 2, IMechE, 2004Dr Neill Weir
Poly-L-lactide (PLLA) specimens were degraded in phosphate-buffered solution at 50°C and 70°C to evaluate accelerated degradation compared to physiological degradation at 37°C. Molecular weight, mechanical properties, and thermal properties were analyzed over time. At both 50°C and 70°C, molecular weight decreased more rapidly than at 37°C, with over 90% reduction by 115 days at 50°C and 95% by 23 days at 70°C. Degradation mechanisms appeared similar to 37°C, though autocatalysis may be affected at higher temperatures. Increased temperature provided accelerated degradation of PLLA compared to physiological conditions.
— Oligoguanidine with chain extension were synthesized by condensation and cross-linking polymerizations in an attempt to increase molecular weight and charge density of the anti microbial oligoguanidine. The reactions are procedure at 170 o C for 5h with ratio molar of HMDA: GHC = 1: 1.1, refined by vacuum filter at 60 o C. The Oligoguanidine OHMG.HCl synthesized has molecular weight equal 521 g/mol, chain structure and good water solubility. The comparison results of the antimicrobial activities of oligoguanidine with chloramine B indicated that MIC index of OHMG.HCl is 5ppm during MIC index of chloramine B is 50 ppm; MBC of OHMG.HCl is 12 minutes and MBC of chloramine B is 11 minutes; The SEM, TEM imagines exhibited clear biocide, low residue microorganism of OHMG.HCl. The LC-MS spectrum indicates the presence of haloacetic acid following the bactericidal action of chloramphen B, while OHGM.HCl is not available. This result confirms the environmental friendliness of oligoguanidine.
This doctoral thesis uses computational methods like density functional theory and molecular dynamics simulations to study the structural and functional role of cytochrome P450 enzymes. It investigates the metabolism of various substrates by CYP3A4 and CYP450 enzymes to understand reaction pathways and influence of substrate structure on reactivity. Specific reactions studied include hydroxylation of phenyl rings, morpholine rings, and camphor. Flexibility studies using the RIGIX program also examined how the protein environment modulates electronic structure and reactivity. The research provides new insights into CYP450 catalysis at the molecular level and could aid in drug design.
Polyamidoamine (PAMAM) dendrimers has
been anchored on functionalized carbon nanofibers (CNF)
and supported Pt–Ru nanoparticles have been prepared with
NaBH4 as a reducing agent. The samples were characterized
by X-ray diffraction, scanning electron microscopy,
and transmission electron microscopy (TEM) analysis. It
was shown that Pt–Ru particles with small average size
(2.6 nm) were uniformly dispersed on PAMAM/CNF
composite support and displayed the characteristic diffraction
peaks of Pt face-centered cubic structure. The electrocatalytic
activities of the prepared-composites (20% Pt–Ru/PAMAMCNF)
were examined by using cyclic voltammetry for
oxidation of methanol. The electrocatalytic activity of the
CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode
for methanol oxidation showed better performance than that
of commercially available Johnson Mathey 20% Pt–Ru/C
catalyst. The results imply that CNF-based PAMAM composite
electrodes are excellent potential candidates for
application in direct methanol fuel cells.
This study investigated the electrochemical oxidation of catechols in the presence of 4-amino-3-thio-1,2,4-triazole (3) using cyclic voltammetry and controlled-potential coulometry. Results showed that catechols reacted with compound 3 via an intramolecular cyclization reaction to form 1,2,4-triazino[5,4-b]-1,3,4-thiadiazine derivatives. The observed homogeneous rate constants for the Michael addition reaction were estimated by comparing experimental voltammograms to digitally simulated responses. The oxidation mechanism was proposed to follow an electron transfer-chemical reaction-electron transfer-chemical reaction pathway based on diagnostic criteria for
Antibacterial Application of Novel Mixed-Ligand Dithiocarbamate Complexes of ...IOSR Journals
The document summarizes the synthesis and characterization of nine novel mixed-ligand dithiocarbamate complexes of nickel(II) and their antibacterial properties. The complexes were prepared by reacting nickel chloride with salicylaldehyde and aryl dithiocarbamates. They were characterized using various analytical techniques and had general formula [Ni(Sal)(Rdtc)]. The complexes exhibited broad-spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella oxytoca and Pseudomonas aureginosa based on agar diffusion tests, suggesting their potential as broad-spectrum antibacterial agents.
Immobilization of Glucose oxidase on PANI-2 Amino Pyridine composite film by ...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis, Characterization and Electrical Properties of Polyaniline Doped wi...IJERA Editor
The polyaniline were prepared by using different inorganic and organic acids via oxidative polymerization
method. The prepared samples were characterized by FTIR, the peaks are found to be at 507 cm˗1, 592 cm˗1, 798
cm˗1, 1138 cm˗1, 1244 cm˗1, 1302 cm˗1, 1471 cm˗1 and 1556 cm˗1. These predominant peaks may be
confirming the formation of polyaniline. The structural analysis was studied by employing XRD; found that
polyaniline is amorphous in nature. The SEM studies reveal that they are agglomerated, irregular and size of
these grain increases with increasing amount of polyaniline with different organic and inorganic acids. The dc
conductivity (dc) as a function of temperature (T) for polyaniline is studied in the temperature range from 30 to
1600C. At higher temperature it is found that conductivity increases because of hopping of polarons from one
localized states to another localized states. The ac conductivity of polyaniline was prepared by oxalic acid show
high conductivity at 106 Hz. This is due to the space charge polarization and electrode polarizations.
In vitro and in vivo evaluation of positively charged liposaccharide derivati...Adel Abdelrahim, PhD
This document describes a study evaluating positively charged liposaccharide derivatives as oral absorption enhancers for delivering anionic drugs. Positively charged liposaccharide derivatives were synthesized and combined with the anionic model drug piperacillin through ion pairing. The conjugates were evaluated in vitro and in vivo to assess antimicrobial activity, plasma stability, permeability across Caco-2 cell monolayers, and oral absorption. Results showed that ion pairing the liposaccharide derivatives with piperacillin improved permeability in Caco-2 cells without altering antimicrobial activity, indicating potential as oral absorption enhancers.
Development of Polyaniline Grafted Chitosan Sensor for Detection of Ammonia &...IRJET Journal
This document summarizes research on developing a polyaniline grafted chitosen sensor for detecting ammonia and ethanol vapors. Six electrochemical sensors were created using polyaniline powder and a polyaniline-grafted-chitosan composite film coated on cloth and paper substrates. The sensors were tested for their sensitivity to ammonia and ethanol vapors. The results showed that the polyaniline-grafted-chitosan composite film sensors had higher current outputs compared to sensors using only polyaniline powder. Specifically, a paper-based sensor and cloth-based sensor coated with the composite film showed better sensitivity to ammonia and ethanol compared to sensors without the chitosan. The research demonstrates the potential
Hplc method development for proteins and polypeptides ijsit 2.4.2IJSIT Editor
In the pharmaceutical field, there is considerable interest in the use of peptides and proteins for therapeutic
purposes. High performance liquid chromatography (HPLC) and its methods of complex peptide or protein
mixtures remains a general method of choice because of the resolution it provides. Unlike small organic
molecules whose chromatographic behavior is described by a finite partitioning equilibrium between the
stationary phase and the mobile phase, proteins and peptides typically do not exhibit such an effect. Instead,
they exhibit an adsorption phenomenon in which the polypeptide is adsorbed onto the stationary phase and
elutes only when the solvent strength of the mobile phase is sufficient to compete with the hydrophobic
forces keeping it there. For this reason, elution of peptides or proteins from reversed-phase supports is by
gradients of increasing solvent strength. There are other differences that one needs to be aware of in order to
develop HPLC methods for separations of proteins and peptides as efficiently as possible.
Effects of heat treatment on the catalytic activity and methanol tolerance of...sunidevi
This document summarizes a study on the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Carbon-supported platinum (Pt/C) and platinum alloy (Pt-Co/C, Pt-Cu/C, Pt-Fe/C, Pt-Ni/C) catalysts were subjected to heat treatments at different temperatures. X-ray diffraction, transmission electron microscopy, and electrochemical measurements were used to characterize the catalysts and evaluate their oxygen reduction reaction activity and methanol tolerance. The results showed that heat treatment improved catalytic activity by increasing particle size but the optimal temperature depended on the catalyst. Pt-Cu/C treated at 350°C showed the highest activity and
Crosslinked Microgels as Platform for Hydrolytic Catalysts Article pubs.acs.o...aaaa zzzz
This document describes the development of a new protocol for synthesizing crosslinked microgels via UV-initiated free radical polymerization of miniemulsions at ambient temperature or below. The microgels are formed from butyl acrylate, ethylene glycol dimethacrylate, and a catalyst-precursor ligand. The catalytic activity of the microgels is demonstrated through the hydrolysis of 4-methylumbelliferyl β-D-galactopyranoside. A correlation is observed between the crosslinking content of the microgels and their catalytic proficiency, with peak performance at 40 mol% crosslinking.
Visible Spectrophotometric Determination of Gemigliptin Using Charge Transfer...Ratnakaram Venkata Nadh
A visible spectrophotometric method was developed and validated for the determination of gemigliptin present in bulk drug and tablet formulation. It involves an indirect method of charge transfer complex formation in presence of NBS, metol and suphanilic acid. Gemigliptin was subjected to oxidation with excess amount of oxidant (NBS) and the unconsumed NBS oxidizes metol to give p-N-methylbenzoquinone monoamine (PNMM) which in turn forms a charge transfer complex with sulphanilic acid. Then validated the above developed method as per the current ICH guidelines. An excellent correlation coefficient (> 0.999) was found for the obtained regression equation
(y = –0.0302x + 0.928) in the range of 2.0–30.0 μg mL-1. The method was found to be simple and rapid because it does not involve any solvent extraction. The recovery levels of the drug were in the range 99.92 – 100.08.
The document summarizes a study that used a palladium catalyst to synthesize benzofuran through a Sonogashira coupling reaction between 5-iodovanillin and 3-methyl-3-butyne-2-ol. The reaction was carried out using various amounts of palladium acetate, triphenylphosphine, and solvent. NMR spectroscopy showed the product formed, though it was impure likely due to side reactions promoted by the copper co-catalyst. While the reaction showed good atom economy, the yields were relatively low at 7.45% maximum. Further optimization is needed to improve purity and yields.
OBC epoxidations paper - Queen Mary University LONDON UK - Thomas FollierThomas Follier
This document reports on a study of the catalytic activity of manganese complexes with two similar polyamine ligands (7 and 8) that differ by the presence of a secondary or tertiary nitrogen, in the epoxidation of styrene. Ligand 7 showed the highest activity with MnSO4 and H2O2, while ligand 8 was most effective with Mn(OTf)2, MnCl2, and Mn(ClO4)2 using peracetic acid. Kinetic analysis indicated the structural differences in the ligands lead to differences in the nature of the active species formed. Ligand 7 with MnSO4 produced the epoxide in 78% yield, while ligand 8 with Mn(OT
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...sunitha81
Poly (o-phenylenediamine) (PoPD) microrods were obtained by interfacial
polymerization using ferric chloride as oxidant and without any template or
functional dopant. Pt/PoPD nanocatalysts were prepared by the reduction of chloroplatinic
acid with sodium borohydride, and the composite catalysts formed were
characterized by X-ray diffraction and electrochemical methods. The nanocomposite
of Pt/PoPD microrods has been explored for their electro-catalytic performance
towards oxidation of methanol. The electro-catalytic activity of Pt/PoPD was
found to be much higher (current density 1.96 mA/cm2 at 0.70 V) in comparison to
Pt/Vulcan electrodes (the current density values of 1.56 mA/cm2 at 0.71 V) which
may be attributed to the microrod morphology of PoPD that facilitate the effective
dispersion of Pt particles and easier access of methanol towards the catalytic sites.
This document describes the development of a fluorescent probe for sensing thiamine (vitamin B1) based on arginine-functionalized graphene quantum dots (Arg-GQDs). Arg-GQDs were synthesized through a one-pot hydrothermal method using citric acid and arginine as carbon and nitrogen precursors. The Arg-GQDs exhibited strong blue fluorescence with a quantum yield of 28.3%. The fluorescence of the Arg-GQDs was selectively quenched by Ag+ ions and recovered upon addition of thiamine, providing the basis for a fluorescence "off-on" probe for thiamine. Central composite design and response surface methodology were used to optimize the detection conditions, including pH, time
A powerful and convenient reaction procedure for the C-N coupling reaction (the Buchwald-Hartwig reaction), yielding products of N-arylanilines and N-arylamines in both conventional heating and microwave irradiation has been reported. The protocol utilizes a stable and new supper ferromagnetic nanoparticle chelating N-heterocyclic dicarbene palladium(II) complex (Pd-NHC) as catalyst which helps/allows us to complete the reaction with only 0.002 mol% Pd producing high yield products. We also examined the reusability of the catalyst. It was found that the catalyst could be recovered by external magnetic field and reused for seven times without obvious loss in catalytic activity.
Technique that is used to elucidate mechanism of a reaction or in a metabolic pathway and in a cell. The labeling takes place by exchanging a specific atom with their isotope. The detecting of the isotopes in the product helps to understand the possible mechanism and the stereochemistry in this sequence of the reaction. The detection of the isotopic labels is dependent on the kind of isotope. Radioactive isotopes like 3H 14C are measured radiochemical. Stable isotopes like 2H and 13C are detected for example with NMR- and IR-spectroscopy.
Kristina Melnik & Stephanie Felten (Undergraduate Students)
University of Utah
2014
Whole Chain Electron Transport under Nitrogen Stress in Spirulina PlatensisIRJET Journal
1. The study examines the effect of nitrogen stress on whole chain electron transport in the cyanobacterium Spirulina platensis. Nitrogen stress is induced by incubating cells in growth medium containing reduced nitrate concentrations ranging from 40-80 μM.
2. Nitrogen stress results in a time-dependent inhibition of whole chain electron transport. Incubation for 24 hours in 60 μM nitrate medium causes a 44% loss, increasing to 54% after 48 hours. Reducing nitrate to 40 μM causes a 52% loss after 24 hours.
3. Photosystem II activity is more sensitive to nitrogen stress than Photosystem I activity. Nitrogen stress causes concentration-dependent inhibition of Photosystem II electron transport
Degradation of poly-L-lactide. Part 2, IMechE, 2004Dr Neill Weir
Poly-L-lactide (PLLA) specimens were degraded in phosphate-buffered solution at 50°C and 70°C to evaluate accelerated degradation compared to physiological degradation at 37°C. Molecular weight, mechanical properties, and thermal properties were analyzed over time. At both 50°C and 70°C, molecular weight decreased more rapidly than at 37°C, with over 90% reduction by 115 days at 50°C and 95% by 23 days at 70°C. Degradation mechanisms appeared similar to 37°C, though autocatalysis may be affected at higher temperatures. Increased temperature provided accelerated degradation of PLLA compared to physiological conditions.
— Oligoguanidine with chain extension were synthesized by condensation and cross-linking polymerizations in an attempt to increase molecular weight and charge density of the anti microbial oligoguanidine. The reactions are procedure at 170 o C for 5h with ratio molar of HMDA: GHC = 1: 1.1, refined by vacuum filter at 60 o C. The Oligoguanidine OHMG.HCl synthesized has molecular weight equal 521 g/mol, chain structure and good water solubility. The comparison results of the antimicrobial activities of oligoguanidine with chloramine B indicated that MIC index of OHMG.HCl is 5ppm during MIC index of chloramine B is 50 ppm; MBC of OHMG.HCl is 12 minutes and MBC of chloramine B is 11 minutes; The SEM, TEM imagines exhibited clear biocide, low residue microorganism of OHMG.HCl. The LC-MS spectrum indicates the presence of haloacetic acid following the bactericidal action of chloramphen B, while OHGM.HCl is not available. This result confirms the environmental friendliness of oligoguanidine.
This doctoral thesis uses computational methods like density functional theory and molecular dynamics simulations to study the structural and functional role of cytochrome P450 enzymes. It investigates the metabolism of various substrates by CYP3A4 and CYP450 enzymes to understand reaction pathways and influence of substrate structure on reactivity. Specific reactions studied include hydroxylation of phenyl rings, morpholine rings, and camphor. Flexibility studies using the RIGIX program also examined how the protein environment modulates electronic structure and reactivity. The research provides new insights into CYP450 catalysis at the molecular level and could aid in drug design.
Polyamidoamine (PAMAM) dendrimers has
been anchored on functionalized carbon nanofibers (CNF)
and supported Pt–Ru nanoparticles have been prepared with
NaBH4 as a reducing agent. The samples were characterized
by X-ray diffraction, scanning electron microscopy,
and transmission electron microscopy (TEM) analysis. It
was shown that Pt–Ru particles with small average size
(2.6 nm) were uniformly dispersed on PAMAM/CNF
composite support and displayed the characteristic diffraction
peaks of Pt face-centered cubic structure. The electrocatalytic
activities of the prepared-composites (20% Pt–Ru/PAMAMCNF)
were examined by using cyclic voltammetry for
oxidation of methanol. The electrocatalytic activity of the
CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode
for methanol oxidation showed better performance than that
of commercially available Johnson Mathey 20% Pt–Ru/C
catalyst. The results imply that CNF-based PAMAM composite
electrodes are excellent potential candidates for
application in direct methanol fuel cells.
This study investigated the electrochemical oxidation of catechols in the presence of 4-amino-3-thio-1,2,4-triazole (3) using cyclic voltammetry and controlled-potential coulometry. Results showed that catechols reacted with compound 3 via an intramolecular cyclization reaction to form 1,2,4-triazino[5,4-b]-1,3,4-thiadiazine derivatives. The observed homogeneous rate constants for the Michael addition reaction were estimated by comparing experimental voltammograms to digitally simulated responses. The oxidation mechanism was proposed to follow an electron transfer-chemical reaction-electron transfer-chemical reaction pathway based on diagnostic criteria for
Antibacterial Application of Novel Mixed-Ligand Dithiocarbamate Complexes of ...IOSR Journals
The document summarizes the synthesis and characterization of nine novel mixed-ligand dithiocarbamate complexes of nickel(II) and their antibacterial properties. The complexes were prepared by reacting nickel chloride with salicylaldehyde and aryl dithiocarbamates. They were characterized using various analytical techniques and had general formula [Ni(Sal)(Rdtc)]. The complexes exhibited broad-spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella oxytoca and Pseudomonas aureginosa based on agar diffusion tests, suggesting their potential as broad-spectrum antibacterial agents.
Immobilization of Glucose oxidase on PANI-2 Amino Pyridine composite film by ...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Synthesis, Characterization and Electrical Properties of Polyaniline Doped wi...IJERA Editor
The polyaniline were prepared by using different inorganic and organic acids via oxidative polymerization
method. The prepared samples were characterized by FTIR, the peaks are found to be at 507 cm˗1, 592 cm˗1, 798
cm˗1, 1138 cm˗1, 1244 cm˗1, 1302 cm˗1, 1471 cm˗1 and 1556 cm˗1. These predominant peaks may be
confirming the formation of polyaniline. The structural analysis was studied by employing XRD; found that
polyaniline is amorphous in nature. The SEM studies reveal that they are agglomerated, irregular and size of
these grain increases with increasing amount of polyaniline with different organic and inorganic acids. The dc
conductivity (dc) as a function of temperature (T) for polyaniline is studied in the temperature range from 30 to
1600C. At higher temperature it is found that conductivity increases because of hopping of polarons from one
localized states to another localized states. The ac conductivity of polyaniline was prepared by oxalic acid show
high conductivity at 106 Hz. This is due to the space charge polarization and electrode polarizations.
In vitro and in vivo evaluation of positively charged liposaccharide derivati...Adel Abdelrahim, PhD
This document describes a study evaluating positively charged liposaccharide derivatives as oral absorption enhancers for delivering anionic drugs. Positively charged liposaccharide derivatives were synthesized and combined with the anionic model drug piperacillin through ion pairing. The conjugates were evaluated in vitro and in vivo to assess antimicrobial activity, plasma stability, permeability across Caco-2 cell monolayers, and oral absorption. Results showed that ion pairing the liposaccharide derivatives with piperacillin improved permeability in Caco-2 cells without altering antimicrobial activity, indicating potential as oral absorption enhancers.
Development of Polyaniline Grafted Chitosan Sensor for Detection of Ammonia &...IRJET Journal
This document summarizes research on developing a polyaniline grafted chitosen sensor for detecting ammonia and ethanol vapors. Six electrochemical sensors were created using polyaniline powder and a polyaniline-grafted-chitosan composite film coated on cloth and paper substrates. The sensors were tested for their sensitivity to ammonia and ethanol vapors. The results showed that the polyaniline-grafted-chitosan composite film sensors had higher current outputs compared to sensors using only polyaniline powder. Specifically, a paper-based sensor and cloth-based sensor coated with the composite film showed better sensitivity to ammonia and ethanol compared to sensors without the chitosan. The research demonstrates the potential
Hplc method development for proteins and polypeptides ijsit 2.4.2IJSIT Editor
In the pharmaceutical field, there is considerable interest in the use of peptides and proteins for therapeutic
purposes. High performance liquid chromatography (HPLC) and its methods of complex peptide or protein
mixtures remains a general method of choice because of the resolution it provides. Unlike small organic
molecules whose chromatographic behavior is described by a finite partitioning equilibrium between the
stationary phase and the mobile phase, proteins and peptides typically do not exhibit such an effect. Instead,
they exhibit an adsorption phenomenon in which the polypeptide is adsorbed onto the stationary phase and
elutes only when the solvent strength of the mobile phase is sufficient to compete with the hydrophobic
forces keeping it there. For this reason, elution of peptides or proteins from reversed-phase supports is by
gradients of increasing solvent strength. There are other differences that one needs to be aware of in order to
develop HPLC methods for separations of proteins and peptides as efficiently as possible.
This document describes a study on using different forms of polyaniline (PANI) - Emeraldine Base PANI (EB-PANI), Emeraldine Salt PANI (ES-PANI), and Leuco Emeraldine Base PANI (LEB-PANI) - as sensing materials for detecting dissolved oxygen levels in solutions. The PANI forms were characterized using UV-Vis spectroscopy and their oxygen sensitivity was evaluated using cyclic voltammetry. The cyclic voltammetry measurements showed variations in current corresponding to different oxygen concentrations, indicating the potential of using PANI-coated electrodes as dissolved oxygen sensors. In particular, results showed LEB-PANI may be suitable for detecting low concentrations of dissolved oxygen in
This document discusses kinetic methods of analysis using potentiometric and spectrophotometric detectors. It provides examples of using potentiometric chemical sensors to monitor the kinetic formation of metal-fluoride complexes. Specifically, it describes using a fluoride ion-selective electrode to monitor the formation of iron(III)-fluoride and aluminum-fluoride complexes over time, where the initial rates of complex formation are proportional to the metal ion concentrations. The kinetics of aluminum-fluoride complexation are also studied over a range of pH values.
The document examines the effects of acid on the chlorophyll production and biomass of common duckweed (Lemna minor L.). Two experiments were conducted exposing duckweed to pH levels of 4.1, 5.4, and 6.5 (control) over 10-12 days. The first experiment showed no significant differences in biomass between pH treatments. The second experiment found significantly lower biomass at pH 4.1 compared to pH 5.4 and 6.5. Neither experiment found significant differences in chlorophyll content between pH treatments. The results partially supported the hypothesis, showing acid inhibited biomass but not through impacts on chlorophyll. Longer exposure periods or lower pH levels may be needed to impact chlorophyll.
Ionic Liquids Modify the Performance of Carbon Based Potentiometric SensorsFatemeh Sedaghatpour
This document describes a study that tested the performance of potentiometric sensors constructed with carbon ionic liquid electrodes (CILEs) compared to traditional carbon paste electrodes (CPEs). Two ionic liquids, N-octylpyridinium hexafluorophosphate and 1-butyl-3-methylimidazolium hexafluorophosphate, were used as binders in CILEs. The results showed that CILE-based sensors exhibited improved Nernstian slope, selectivity, response time, and response stability compared to CPE-based sensors. Specifically, a CILE containing 30% N-octylpyridinium hexafluorophosphate and 70% graphite
Vardenafil is a PDE5 inhibitor used to treat erectile dysfunction. This document discusses several studies that developed and validated analytical methods for quantifying vardenafil concentration. One study used thin layer chromatography with densitometric detection to simultaneously estimate vardenafil and dapoxetine in pharmaceutical formulations. Another used HPLC with amperometric detection employing a boron-doped diamond electrode to determine vardenafil and related metabolites in plasma. A third developed a HPLC-chemiluminescence method to quantify trace levels of vardenafil in dietary supplements.
This document describes new methods for using size-exclusion chromatography coupled with light scattering, refractive index, and UV detection to determine the degree of polymer conjugation to proteins and protein association states. It presents techniques to determine the degree of polyethylene glycol conjugation to RNase A and BDNF, and the association states of these molecules, without requiring calibration curves. The methods are also applied to determining the degree of erythropoietin glycosylation.
Mechanism of the Reaction of Plasma Albumin with Formaldehyde in Ethanol - Wa...IOSR Journals
The Spectrophotometric determination of the acid dissociation/ionisation constant (pKa) of plasma albumin-formaldehyde adduct in both water solution and Ethanol solutions was carried out in this study. The pKa values obtained in both media were used to establish the Bronsted-linear type constants from plots of pKa against logarithm of second order rate constants obtained at varying pHs in the study. The result of the pKa values obtained in both water solution and ethanol-water mixtures were found to be in the range of 5.0 - 8.0. This pointed to the fact that only lysine residue with pKa value 8.3 that might have possibly reacted with formaldehyde in this reaction of all the known amino acid residues in plasma albumin. The corresponding Brønsted-type plots proportionality constants (β) for the reaction in water and ethanol-water mixtures were found to be β = 0.059 and 0.0057 respectively. The reaction mechanisms that have low values for proportionality constants α or β are considered to have a transition state closely resembling the reactant with little proton transfer (Cox et al, 1988). Thus, one would suggest that the cross-linking of formaldehyde with plasma albumin in water and ethanol-water mixtures proceeds through little proton transfer
Evaluation of protein and peptide formulations.pptxDivya Pushp
This document discusses stability testing and evaluation methods for protein formulations. Stability testing ensures products maintain specifications over shelf life under various storage conditions. Evaluations include bioassays to assess potency, which can be in vitro by monitoring cell responses to proteins or in vivo by monitoring animal pharmacological responses. Common evaluation methods are UV spectroscopy, Bradford assay, thermal analysis like DSC and TGA, and chromatography techniques like HPLC, ion exchange, and chromatofocusing.
This study investigated the polymerization of lactic acid as a model for prebiotic peptide formation via ester-amide exchange. Lactic acid was polymerized in a closed system at 85°C over various time points. HPLC and 1H-NMR were used to analyze the polymers and determine degree of polymerization (DP) and total lactic acid units. DP was found to increase with time while total units decreased, showing polymer regeneration. Methods showed consistent results within 10-15% error. Further studies will compare kinetics to a computer simulation to determine rate constants and model polymerization from various monomers.
Understanding the adsorption mechanisms in nanostructured polymer films has become crucial for their use in technological applications, since film properties vary considerably with the experimental conditions utilized for film fabrication. In this paper, we employ small-angle X-ray
scattering (SAXS) to investigate solutions of polyanilines and correlate the chain conformations with morphological features of the nanostructured films obtained with atomic force microscopy (AFM). It is shown that aggregates formed already in solution affect the film morphology; in
particular, at early stages of adsorption film morphology appears entirely governed by the chain conformation in solution and adsorption of aggregates. We also use SAXS data for modeling poly(o-ethoxyaniline) (POEA) particle shape through an ab initio procedure based on simulated
annealing using the dummy atom model (DAM), which is then compared to the morphological features of POEA films fabricated with distinct pHs and doping acids. Interestingly, when the derivative POEA is doped with p-toluene sulfonic acid (TSA), the resulting films exhibit a fibrillar morphology—seen with atomic force microscopy and transmission electron microscopy—that is consistent with the cylindrical shape inferred from the SAXS data. This is in contrast with the globular morphology observed for POEA films doped with other acids.
This document describes a study that characterized the major and minor groove environments of DNA using fluorescent probes. Specifically:
- Fluorescent oligonucleotides were created by incorporating a dansyl fluorophore into the major groove at specific sites.
- The fluorescence properties of these probes were used to estimate that the dielectric constant of the major groove is around 55D, compared to 20D for the minor groove.
- Binding of the minor groove ligand netropsin could be quantitatively monitored by changes in fluorescence of the dansyl group in the major groove, suggesting an information network between the two grooves.
This document provides information on biosensors. It defines a biosensor as a device that responds to the presence of a specific analyte by producing an electrical signal proportional to the analyte's concentration. It notes biosensors have three main components: a receptor, transducer, and electronics. The document discusses the different types of biosensors including electrochemical, optical, piezoelectric, and thermometric biosensors. It provides examples of applications of biosensors in food analysis, quality control, and dairy industries for detecting substances like glucose, lactose, and pathogens.
The document discusses various applications of nanomaterials in catalysis. It begins by introducing different types of catalysts and how nanocatalysts combine advantages of homogeneous and heterogeneous systems by having a high surface area like homogeneous catalysts while also being easily separable like heterogeneous catalysts. Several examples of nanocatalyst applications are then summarized in areas like water purification, biodiesel production, drug delivery, fuel cells, environmental protection, and solar cells. The document emphasizes how nanocatalysts provide benefits like high activity, selectivity, stability, and being energy efficient.
This document reports on the synthesis and characterization of polyethyleneimine-anchored copper(II) complexes and their in vitro DNA binding studies and cytotoxicity. Specifically, it synthesized copper(II) complexes containing 1,10-phenanthroline and L-tyrosine ligands bound to a branched polyethyleneimine polymer. It characterized the complexes using various techniques and studied their binding to calf thymus DNA. It found that the complex with the highest degree of copper(II) coordination bound most strongly to DNA. Finally, it evaluated the cytotoxic activity of this complex against MCF-7 breast cancer cells.
This document outlines a study investigating the cage effects of ionic liquids. The goals are to synthesize naphthyl ester starting materials and purify them for use in a photo-Fries reaction probe experiment to quantify cage effects. Naphthyl esters were synthesized from naphthols and acid chlorides. The esters were purified using recrystallization or column chromatography and analyzed for purity using melting point, TLC, and GC/MS. The purified esters will be used in future photolysis experiments coupled with GC/MS to quantify cage effects of ionic liquids and hexanes as a control. This will provide insight into how effectively solute molecules can escape solvent cages in ionic liquids.
Similar to Ijpar 14 617 manjusinghA label-free electrochemical protein sensor of perchloric acid doped polyaniline (20)
Patient compliance: Challenges in management of cardiac diseases in Kuala Lum...pharmaindexing
Background
The objective of this study was to investigate the degree of compliance among cardiac patients who attend the health facilities in Kuala Lumpur and Perak, Malaysia. The reasons for non-compliance and recommendations from healthcare professionals were also evaluated.
Method
A cross-sectional study of 400 patients and 100 healthcare professionals was carried out. This study utilizes variables on external factors and internal factors as the measurement tools. The questionnaire which consists of Morisky self-reported medication adherence questions was administered to patients and causes for non-compliance sought. Questionnaire for healthcare professionals was used to determine strategies that can improve compliance rate.
Results
The study revealed a 15.8% of high adherence rate, 54.3% of moderate adherence rate and 30% of poor adherence to cardiovascular disease medications. The chi-square tests showed the strong association between dependent and independent variables. The model chosen for testing the patient compliance through external and internal factors gives an R2 value of 85.0% with an adjusted R2 of 84.7%. The F value (317.187) was also significant (p=0.000) which means that the variables have better fit in the multivariate model. The major reasons determined for non-adherence were attitudes and beliefs, lifestyle, side effects and cost of medications. The study recommends that pharmacists and dispensing technicians should be adequately qualified to provide proper counselling to cardiac patients on their medicines and disease conditions.
Conclusion
The result of this study is of value to health care providers. Compliance to cardiovascular medications will avoid treatment failures encountered in therapy.
Overview on Recurrence Pregnancy Loss etiology and risk factorspharmaindexing
Recurrent pregnancy loss (RPL) can be defined as more than two to three consecutive miscarriages before 20 weeks’ gestation; it affects approximately 1% to 2% of women. RPL is a multifactorial disease. It is very important to study the etiology and risk factors of RPL to find the best diagnostic tests and suitable therapeutic intervention. This article will discuss the current understanding etiologies and risk factors of RPL.
Novel treatments for asthma: Corticosteroids and other anti-inflammatory agents.pharmaindexing
Asthma management is a challenge due to the prevalence of disease in the world. Based on the immunological and inflammatory mechanisms of asthma, corticosteroids and anti-inflammatory participate greatly in the treatment plan. Due to different reasons, there is still an unmet need to develop new agents in this field. A lot of compounds with anti-inflammatory effect are investigated in both pre-clinical and clinical studies.
A review on liver disorders and screening models of hepatoprotective agentspharmaindexing
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of bio chemicals necessary for digestion. The liver is necessary for survival; there is currently no way to compensate for the absence of liver function long term, although liver dialysis can be used short term.
Carbamazepine induced Steven Johnson syndrome: A case reportpharmaindexing
Drugs are the most common cause that induces Steven Johnson syndrome (SJS) and includes antiepileptic drugs, antiretroviral drugs, anti-tuberculosis drugs, Sulphonamides, fluoroquinolones, penicillins, non-Steroidal anti-inflammatory drugs, Multivitamins. The genetic markers are also the cause for carbamazepine induced Steven Johnson Syndrome. In our study, the antiepileptic drug (Carbamazepine) is the cause for Steven Johnson Syndrome. A female patient aged 25 years came to the hospital with the complaints of bubbling over the skin and all over the body with papillary vesicles associated with pain and irritation, fever, myalgia, and nausea. The patient is known case of Phenytoin induced Steven Johnson Syndrome. In this case the patient developed the Steven Johnson Syndrome approximately after one month after starting the carbamazepine.By the withdrawal of the drug, the condition of the patient was improved.
Monoherbal formulation development for laxative activitypharmaindexing
The Ayurvedic Pharmacopoeia specifically approves flaxseed as a poultice for boils externally and demulcent or laxative internally. In this study monoherbal formulation development for laxative activity of flaxseed was undertaken. The plantLinumusitatissimumhasshowed higher percentage of total ash as well as alcohol soluble extractive values. The aqueous extract of Linumusitatissimumwas prepared by using pilot scale extraction plant and spray drying unit. The qualitative phytochemical studies reveal the presence of amino acids, carbohydrates, vitamins and proteins. From the available literatures it was found that Linumusitatissimum contains more number of amino acids. The formulated tablets showed acceptable pharmacopoeial limits and complies with specifications for thickness, hardness, friability and weight variation. The formulation has showed better laxative activity indicating additive property of the combined phytoconstituents of the plant.
Monoherbal formulation development for laxative activitypharmaindexing
The Ayurvedic Pharmacopoeia specifically approves flaxseed as a poultice for boils externally and demulcent or laxative internally. In this study monoherbal formulation development for laxative activity of flaxseed was undertaken. The plantLinumusitatissimumhasshowed higher percentage of total ash as well as alcohol soluble extractive values. The aqueous extract of Linumusitatissimumwas prepared by using pilot scale extraction plant and spray drying unit. The qualitative phytochemical studies reveal the presence of amino acids, carbohydrates, vitamins and proteins. From the available literatures it was found that Linumusitatissimum contains more number of amino acids. The formulated tablets showed acceptable pharmacopoeial limits and complies with specifications for thickness, hardness, friability and weight variation. The formulation has showed better laxative activity indicating additive property of the combined phytoconstituents of the plant.
Pneumonia and respiratory failure from swine origin influenza H1n1pharmaindexing
Swine influenza (swine flu) became alarming health concern when World Health Organization declared as “public health emergency of international concern” on April 25, 2009. After documentation of human-to-human transmission of the virus in at least three countries of two WHO regions, the WHO raised the pandemic level to 6.1 During the 1918, flu pandemic infected one-third of the world's population (an estimated 500 million people) and caused approximately 50 million deaths.2 In 1976, an outbreak of swine influenza occurred in New Jersey, USA, which involved more than 200 cases, some of them severe, resulting in one death.3 In 1988, another fatality was reported as a complication of swine influenza.
A descriptive study on newborn care among postnatal mothers in selected mater...pharmaindexing
The newborn health challenge faced by India is more formidable than that experienced by any other country in the world. The newborn health is inevitably affected by the traditional care practices of the mothers causing high infant morbidity and mortality.The aim of the study were determine the knowledge, attitude and practice of postnatal mothers regarding new born care and find out the association between knowledge, attitude and practice of postnatal mothers regarding new born care and to determine the association between these as well as with the selected demographic variables. A descriptive study was conducted to assess the knowledge, attitude and practice of postnatal mothers regarding new born care in selected maternity centres in Madurai. Survey approach was employed to select sample and it consisted of 100 postnatal mothers. Data was collected using structured interview schedule. Findings of the study showed that 65% of postnatal mothers had moderate knowledge; 61% had favourable attitude and 57% of them had high practice of new born care. There was a significant association between knowledge and attitude (r=+0.567), knowledge and practice (r=+0.388), attitude and practice (r=+0.321) .There was a significant association between knowledge and education, monthly family income and obstetrical score at p<0.05. Findings of the study indicated the need to conduct frequent assessment of knowledge, attitude and practice of postnatal mothers regarding new born care. Awareness and attitude of the mothers towards new born care still has lots of lacunae especially in those who belong to the lower socio economic statusand poorly educated postnatal mothers. So it is imperative to provide comprehensive training in the field of new born care for mothers during pregnancy
Late 19th century was evident of intelligent biomaterial; which has changed researcher’s perspective towards science and technology. This intelligent biomaterial are envisioned to have huge impact on Healthcare from sequential signalling of biomedical molecule, mimicking natural gene, an effective drug carrier, to high resolution diagnostic tool.From drug discovery aspect many of NCE fail to reach therapeutic potential due to PK/ PD profile. Nanotechnology has changed the face of drug discovery form chemical evaluation to structure of proteins in signalling pathways and development of chemical antibody. Nanotechnology from lab to market approval is long process due to regulatory evaluation. Though it seems to be bright future market it has to go through a long process from being innovation to complete market product. This makes whole process expensive making investor reluctant to invest in big projects.Western world is aware of dramatic potential of nano-projects; which has its limitation in financial investments; with major challenge of transforming nano science to commercial pharmaceutical product.
The Flaws in health practice in post-operative management of a patient in ter...pharmaindexing
This case study summarizes the treatment of a 4-year old child with congenital urinary tract obstruction who presented with constipation, fever, and cough. Laboratory tests found low electrolyte levels, high blood acids, and kidney damage. The child's treatment included surgery, dialysis to correct electrolyte imbalances, and antibiotics for chest infection. However, the case study notes discrepancies in the post-operative treatment, including questionable antibiotic selection and prescribing of calcium channel blockers not recommended for children. The study concludes there is a need for clinical pharmacists on the healthcare team to improve rational medication use.
Corticosteroid induced disorders – An overviewpharmaindexing
Glucocorticoids are important in the treatment of many inflammatory, allergic, immunologic, and malignant disorders, and the toxicity of glucocorticoids is one of the commonest causes of iatrogenic illness associated with chronic inflammatory disease.Glucocorticoid-induced muscle atrophy is characterized by fast-twitch or type II muscle fiber atrophy. Corticosteroid (CS) therapy is widely used in the treatment of rheumatic diseases.Osteoporosis remains one of its major complications.Steroid induced glaucoma is a form of open angle glaucoma occurring as an adverse effect of corticosteroid therapy. Glucocorticoids induce hepatic and extrahepatic insulin resistance.Glucocorticoid treatment impairs both glucose transport in fat and muscle cells. Corticosteroid-induced psychosis represents a spectrum of psychological changes that can occur at any time during treatment. Cushing’s syndrome describes the signs and symptoms associated with prolonged exposure to inappropriately high levels of the hormone cortisol. Physicians must be aware of these adverse effects and be equipped to manage them.
Anti-inflammatory activity of pupalia lappacea L. Jusspharmaindexing
Pupalia lappacea (L) Juss is an erect shrub used in folklore medicine to treat bone fractures and in inflammatory conditions. Methanolic extract of aerial parts shown is claimed in traditional medicine that the leaves of the plant are used in the treatment of inflammation. In the present study, the methanolic extract of Pupalia lappacea was screened for its anti-inflammatory activity using carageenan induced rat paw edema egg white induced paw oedema models. The methanolic extract at the dose of 200 mg/kg p.o exhibited significant anti-inflammatory activity in carrageenan induced paw edema model (p<0.01). In egg white induced model, methanolic extract at the dose of 200 mg/kg inhibited paw oedema significantly (p<0.01) indicating that both test samples inhibit the increase in number of fibroblasts and synthesis of collagen and mucopolysaccharides during prostaglandin formation during the inflammation. These experimental results have established a pharmacological evidence for the folklore claim of the drug to be used as an anti inflammatory agent. HPTLC analysis of the extract shows the presence of gallic acid 1.24mg/ml, ferulic acid 2.00mg/ml, chlorogenic acid 46.25mg/ml and rutin 7.02mg/ml of the extract which were responsible for the claimed anti-inflammatory action in the animal models studied.
Lucinactant: A new solution in treating neonatal respiratory distress syndrom...pharmaindexing
This document summarizes research on Lucinactant, a novel synthetic surfactant approved by the FDA in 2012 for treatment of neonatal respiratory distress syndrome (RDS). It contains a peptide called sinapultide that mimics the function of human surfactant protein B. Studies found Lucinactant was as effective as or more effective than previous animal-derived surfactants in reducing mortality from RDS, but its pharmacokinetics are not fully understood. The document reviews clinical trials and mechanisms of Lucinactant and discusses its efficacy, safety profile, and potential cost benefits compared to other surfactants.
Bioactivity screening of Soil bacteria against human pathogenspharmaindexing
This study aimed to isolate soil bacteria with potential bioactive properties against human pathogens. 36 bacterial strains were isolated from 3 soil samples and screened against common pathogens. 14 isolates showed antibacterial activity, including against Staphylococcus aureus, Streptococcus faecalis, E. coli, Klebsiella aerogenes, Proteus vulgaris, Pseudomonas aureginosa and Salmonella typhi. The 3 most active bacterial isolates were selected for further production and isolation of their bioactive metabolites. Testing found the metabolites had prominent antibacterial effects against the clinical pathogens studied, indicating their potential as a source of new antimicrobials given the rise in drug resistance.
A study on sigmoid Volvulus presentation and managementpharmaindexing
A study on sigmoid volvulus presentation and management was a 2yr retrospective study done at RMMCH.The diagnosis of sigmoid volvulus was made from a history of large bowel obstruction (constipation, abdominal distension, and abdominal pain), which were often recurrent and plain abdominal radiographs.The morbidity associated isSuperficial wound infection occurred in four patients. All the infected wounds eventually healed with conservative measures. Clinical anastomotic dehiscence was noted in 1 patient for which during relaparotomy proximal colostomy and mucous fistula was done. The mortality associated is shown is there were 9 deaths of which 7 were due to sepsis and 2 were due to comorbid illness. Two out of eight patients for whom a colopexy was done had a recurrent attack of sigmoid volvulus. The duration of hospital stay ranged between 10 and 21 days. Use of sigmoidoscopic detorsion for viable colon should be encouraged. Sigmoidopexy, which is associated with a recurrence rate of 20% in our series of patients, should be used selectively.Hartmann’s procedure is a safe option in sigmoid volvulus with gangrenous bowel. Primary anastomosis in emergency situation can be carried out with morbidity and mortality in patients with viable colon
Evaluation of Preliminary phytochemical on various some medicinal plantspharmaindexing
The present study was carried out to evaluate the physical status and percentage yield of methanolic extract and its fractions of whole plant of Leucas cephalotes, leaves of Hiptage benghalensis and leaves of Kydia calycina were recorded for future references and Preliminary phytochemical screening of MLC, MHB and MKC revealed the presence of carbohydrates, glycosides, saponins, flavonoids, steroidal and phenolic compounds. MLC revealed the presence of all the above mentioned phytoconstituents except saponins and also MKC steroidal compounds. The fractions of MLC, MHB and MKC revealed the presence of glycosides, phenolic compounds, steroids and flavonoids.
Comparision of in vitro antibacterial activity of cefoperazone and levofloxac...pharmaindexing
This study compared the in vitro antibacterial activity of cefoperazone and levofloxacin against various clinical isolates. 120 bacterial isolates from patient samples were tested for susceptibility to cefoperazone and levofloxacin using disc diffusion. Results showed levofloxacin had lower resistance than cefoperazone for E. coli and P. aeruginosa, while cefoperazone was more effective against S. aureus. However, resistance to both antibiotics was gradually increasing, highlighting the need for regular surveillance of antibiotic susceptibility.
Concept of srotas from ayurvedic perspective with special reference to neurologypharmaindexing
Ayurveda is a life science. The researchers of ayurveda could rule out the presence of srotas (channels) spreading throughout the human body. These srotas (channels) are governed by vayu which is using all the srotas (channels) of the body to carry out the functional and physiological activities of the human body without which the human society will not exist. Several synonymous words have been described by the ayurvedicacharyas for srotas. Some are micro and some are macro in structures and they adopt the same colour of the particular dhatus of the body to which it belongs. The aim of the study is to justify that srotas are nothing but innurmerable channels or pathways of the nervous system governed by electric current without which no functional and physiological activities of the human body will develope.
Health promotion survey in overweight and obese students of universities in n...pharmaindexing
Introduction
Overweight and obesity is one of the major health problems in the UK and worldwide. Approximately two-thirds of the population in the UK is either overweight or obese. Overweight and obesity is an important issue that causes distress to most women. Health promotion is the best method to educate overweight and obese women. It is defined as the process enabling people to increase control over and to improve their health by Ottawa Charter for Health Promotion. It is aimed to enhance the well-being of the individuals and their positive attitudes towards prevention of various diseases. In order to make any improvement to the health promotion for overweight and obesity, the risk factors and the opinions from the public should first be identified and addressed.
Methods
Cross-sectional survey design was selected with a questionnaire that consisted of 20 open and close ended questions. A sample size of 196 was determined. The data thus gathered was analyzed using SPSS V20 (Statistical Package for Social Science version 20). Descriptive statistics (fx) and (SD) were used and Chi-square X2 test for association was employed.
Results
Out of the total 196 responses, only (40%) of the students had normal weight (SD 1.1), (25%) students had a good understanding of health promotion (SD 1.6), half (50%) appeared concerned about their weight (SD 0.5), (60%) had an obese family member (0.5). The BMI of students was associated with the presence of an obese member in their family and their weight as a concern for them. (P-value <0.05).
Conclusion
The health promotion service is beneficial as it was found to have raised concerns in the mind of the students regarding over weight and obesity. However it was observed that the understanding of health promotion service was different among students and this is the root of the problem.
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
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Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
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Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
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Ijpar 14 617 manjusinghA label-free electrochemical protein sensor of perchloric acid doped polyaniline
1. 157
* Corresponding author: Manju Singh
E-mail address: manjusingh19@gmail.com
IJPAR |Volume 3 | Issue 1 | Jan-Mar-2014 ISSN: 2320-2831
Available Online at: www.ijpar.com
[Research article]
A label-free electrochemical protein sensor of perchloric acid
doped polyaniline
Manju Singh*1
, Sandeep Yadav2
1
Department of Experimental Medicine (DIMES) University of Genova,
Genova 16132, Italy.
2
Department of Biochemistry, Maharshi Dayanand University, Rohtak 124001,
Haryana, India.
ABSTRACT
In this study, we developed a potentiometric based protein sensor utilizing the interactions between charged
functional moieties of a target protein-protein interaction and the complexation between PANI and dopant
molecules. The sensor response depended on the isoelectric point of the protein. However, this dependency may
be exploited to enhance specificity of protein sensors at specific pH dependence. The conducting polymer was
found to respond by changing potential in the presence of biomolecules, demonstrating a direct chemical to
electronic transduction method. The influence of polymer surface and morphology of finished films was also
studied. This study demonstrated a conducting polymer able to respond to proteins at physiological conditions,
in other words a step towards the integration of these materials into implantable sensing system. Additionally
this sensor also had better ability to recognize the specific protein-protein interaction.
Keywords: Poly aniline, Conducting polymers, Biosensors, Proteins.
INTRODUCTION
A great attention has been paid to the research and
examination in the biosensors which has brought
deep growth in the development of new biosensors
in the past two decades (Wilson and Gifford, 2005;
Kissinger, 2005; Murphy, 2006). A biosensor is a
sensor that uses biological selectivity to limit its
examination to specific key molecules. These types
of biosensor require the expansion of novel sensing
methods, which are sensitive, specific, effective
and low-cost. To address this need, the ability of a
polyaniline (PANI) doped with a variety of acids,
was already used for detecting different
biomolecules by taking advantages of its properties
such as pH sensitivity, ionic strength,
electrochromism and conductivity (Kim et al.,
2000). Polyaniline is one of the most main
conducting polymers among organic and polymer
electronics (Genies et al.,1988; Saxena and
Malhotra, 2003, Lee et al., 2005; Lee et al., 2006)
due to its promising electrical and optical
properties, as well as environmental stability
(Chinn et al., 1995; Chinn et al.,1997;
MacDiarmid,1997). In its emeraldine base form
(see Scheme 1a), PANI behaves as an insulator. To
obtain the conducting emeraldine salt forms of
PANI (see Scheme 1b and 1c), the emeraldine base
is chemically doped by exposure to an acid (see
Figure 1). Polyaniline syntheses are carried out
mostly using aniline hydrochloride solution or a
mixture of an aniline monomer and a dilute
hydrochloride acid (Stejskal and Gelberg, 2002).
To obtain a conducting form of polyaniline, three
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steps are required: (1) polymerization of aniline
with hydrochloride acid, (2) treatment of the
obtained product with base to produce non-
conducting polyaniline, and (3) successive
protonation with an appropriate acid to form a
conducting polyaniline salt (Laska and Widlarz,
2003a). During the pathway, every step is a
separate process and requires purification and
filtration processes. Most of the current studies on
polyaniline are focused on regulatory the
macromolecule properties of the polymer, such as
its conductivity, molecular weight and solubility in
water (Salaneck and Lundstrom, 1987; Stejskal et
al., 1996, 1998; Laska and Widlarz, 2003a).
Among several other processes, one way to modify
the polyaniline properties is by polymerization in
various acids. Inorganic acids such as sulfuric acid
(Neoh et al., 1990), phosphoric acid (Yoon et al.,
1996), and water soluble organic acids, such as
phosphonic and sulphonic acids (Laska and
Widlarz, 2003 a,b), have been investigated with the
probability of increasing conductivity and
solubility in water. It has also been reported that
the temperature at which the polymerization is
conducted controls the molecular structure of the
synthesized polyaniline. When polymerization of
aniline is carried out at a sub-zero temperature,
noticeable rises in both molecular weight and
crystallinity have been observed (Stejskal et al.,
1998). The opportunity of directly converting a
biomolecular chemical interaction into an electrical
signal makes the application of conducting
polymers a promising sensor of transduction
method. The interaction of molecules with the
conducting polymer substrate can change the
dopant charge concentration, and therefore the
conducting properties of the material. This effect
was demonstrated in both gaseous (Bai and Shi
2007; Prasad et al. 2005; Virji et al. 2006) and
liquid phases (Janata and Josowicz 2003; Lange et
al. 2008). A novel conducting polymer sensing
mechanism, utilizing the interaction between
charged functional moieties of a target protein, the
complexation between the PANI and the dopant
molecule, is presented in this work. Non-covalent
interactions between the protein functional
moieties, the acid and the conducting polymer
itself, cause modifications in the extent of doping
present in the conducting polymer materials. The
control of these interactions can be easily changed
by changing the pH of solution. So, in the presence
of a protein, the charge delocalization of the
conducting polymer chain, or the link between the
dopant acid will be modified in a measurable way.
As PANI films do not maintain their conducting
character in non-acidic media (Naudin et.al., 1998)
(i.e. the neutral surroundings necessary for most
proteins to function optimally), the electro
polymerisation process has to be carried out in the
presence of a dopant. For this reason, we focused
on the development of biosensors incorporating
with the perchloric acid (PA) doped PANI. The
insertion of the latter retains electrical neutrality in
the oxidised form of the polymer and also leads to
increments in its structural stability and
conductivity at a broader range of pH values.
Polyaniline synthesized with PA is shown to have
the highest conductivity in a near neutral solution
(pH 6.6). The characteristic of high conductivity in
a neutral solution is desirable to accommodate the
requirement for optimal antibody-antigen reaction
(Barbourand George, 1997). Therefore, polyaniline
polymerized with PA was expected to result in the
best biosensor performance among the other acids
and the sensitivity of the biosensor with polyaniline
protonated with PA was 103 CCID/ml of Bovine
viral diarrhea virus (BVDV) samples and the rest
of the biosensors ranged from 104 to 105
CCID/mls (Tahir et al., 2005). PANI exhibits
unprecedented electroactivity over 8 decades of
pH. We attribute this unusual electrochemical
stability of PANI-PA to the same specific
interactions that are responsible for the enhanced
conductivity.
The recognition of proteins is rare, due to several
technical difficulties: the relative complexities of
the protein surfaces, which carry large numbers of
competing binding sites; their conformational
sensitivity to temperature, pH, the nature of the
solvent; poor solubility in apolar solvents;
biocompatibility, and relatively large molecular
sizes (Sellergren, 2001; Turner et al., 2006). In
most of the reports for the application of MI
technique in protein sensors, elegant chemistry
complementarities and polymerization procedures
are essential for successful recognition (Lin et al.,
2004; Turner et al., 2006). Label-free protein
detection is therefore commonly achieved by
employing biomolecules with high affinity for the
target protein. This ensures much improved
specificity, especially when dealing with a more
complex sample matrix such as urine, cerebral
spinal fluid, and serum, which contains high levels
of serum albumin and immunoglobulins. The goal
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of this work is to recognize protein–protein
interaction by using PANI-PA film.
EXPERIMENTAL METHODS
Materials
Amino propyl triethoxysilane (APTES), aniline,
ammonium persulfate (APS), sodium acetate,
lysozyme (Lys), bovine serum albumin (BSA), and
thaumatin were obtained from Sigma Aldrich Co,
sodium chloride (NaCl) from Merck and perchloric
acid (PA) from fluka. All the proteins and
chemicals were used as received. The
potentiometric measurements were made in a 25
mL beaker equipped Fluke Scopemeter 124 with a
magnetic stirrer. The two-electrode system
consisted of an Ag/AgCl as the reference electrode
and the PANI film doped with PA as the working
electrode. The potentials of the working electrode
against the reference electrode were measured with
a potentiometer. The electrochemical response was
defined as the change of potential after the testing
molecules were added into the solution compared
with that before addition of the test molecules
(expressed as ΔE= E−E0, where E is the potential
after adding the test molecules and E0 is the
potential before adding the test molecules) . For
selected experiments, a pH electrode was
connected to the other channel of the potentiometer
to measure the pH value of the solution.
Fabrication of conducting polymer sensor
PANI was template-synthesized with PA to
generate PA doped PANI. PA was chosen for these
experiments since it was demonstrated to be a
successful polymer acid dopant which could
produce materials with high conductivity (Moon
and Park 1998; Catedral, et al., 2004; Tahir et al.,
2005). In order to make the PANI-PA adhere to a
microfabricated substrate for integration into the
sensing device, APTES was formed on the glass
substrate and the PANI was polymerized in the
presence of the substrate, using what is termed a
dip coating or in situ process. Glass slides were
first cleaned in solvent prior to the silane
functionalization to form the silane layer. The
slides were soaked for 5 min in acetone, followed
by toluene, acetone again and finally by methanol.
The slides were then rinsed in deionized water ten
times. The slides were subsequently cleaned with a
Piranha solution (Sulfuric acid: hydrogen peroxide
in a 2:1 ratio). Sulfuric acid was added to hydrogen
peroxide in a 2:1 ratio, and the slides were soaked
in this solution for 30 min. The slides were again
rinsed with deionized water ten times. Next, the
slides were immersed in a solution of 2 wt%
APTES in acetone for 1 h. Then they were rinsed in
acetone, followed by methanol, and dried with
pressurized nitrogen. The slides were then heated
up to 100°C for at least 12 h to ensure formation of
covalent bonds between the glass and the APTES
(Plueddemann 1991). The functionalized slides
were stored at ambient conditions until use.
To form the PA doped PANI nano film, we
prepared polymerization solutions. The standard
procedure for the polymerization of aniline was
followed and the substrates were immersed in the
solutions during the polymerization reaction see
(Figure 2). A 0.25 M aqueous solution of APS was
mixed with 0.2 M of aniline in 1 M PA as dopant.
The mixture was stirred and maintained at 4°C in
an ice bath and after that, the silane-treated
substrates were immersed in the chilled
polymerization solution. Upon the addition of APS,
the PA–aniline solution turned yellow, and then
eventually brown and blue with time. Finally, the
polymerization medium turned green. This final
color change indicates the presence of the
conducting emeraldine salts of PA doped PANI.
After reacting for 24 hrs, the solution was poured
off, and the substrates were rinsed for 3 days in
deionized water, changing water daily. A sample of
the last rinse was taken and the absorbance of the
solution was analyzed with a UV-vis equipment to
determine if detectable unreacted aniline or
unadhered PANI continued to diffuse from the
surface after rinsing.
Next, 0.05 M sodium acetate buffer was prepared,
with a pH of 6.6 and 8.5. Into this solution, 150
mM sodium chloride was added to control the ionic
strength. Using this buffer, solutions with 10
mg/mL Lys, 10 mg/mL BSA, and 10mg/ml
thaumatin were prepared. PA doped PANI films
were exposed to the buffered protein solutions of
Lys and BSA overnight.
Principle of potentiometric detection
Proteins in aqueous solutions are polyelectrolytes
and have a net electrical charge; the magnitude of
which depends on the isoelectric point of the
protein and on the ionic composition of the
solution. It was demonstrated that when the
charged proteins are trapped into the thin insulating
layer, which is deposited onto a metallic conductor,
the change of the surface potential will occur, and
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this change can be measured potentiometrically
using a reference electrode immersed in the same
solution (Janata, 1975).
Protein-protein interaction based
biomarker
Protein-protein interaction based biomarker was
based on a domain-domain interaction network
flow model to identify signaling pathways from
protein-protein interaction network (Figure 3) it is
centered on two underlying mechanisms. In the
first mechanism, the binding of the small inducer
molecule induces conformational changes at the
protein interacting interface and therefore weakens
the interaction. The second mechanism involves
two small molecules that are connected via a
flexible linker. In addition, the proteins belonging
to the same community are more likely to have
similar functions. Such method detects the
community structure in the molecular network
(Wang et. al., 2007) and found some interesting
hubs of network motifs in the protein-protein
interaction network (Jin et.al. 2007). The modular
or motif underlying biological networks can
provide insight into biomarker prediction.
Targeting protein-protein interactions, which are of
central importance to virtually every cellular
process, has enormous therapeutic potential. Many
researchers focus on the identification of small
molecules that specifically disrupt disease-
promoting protein-protein interactions for
therapeutic applications. Although considerable
progress has been made in the past several years,
the discovery of small molecule drugs that disrupt
protein–protein interactions still faces a number of
significant challenges. As an example, small and
deep cavities that can serve as binding sites for
small molecules are rarely found at the interface of
interacting protein pairs, as the contact surfaces
involved in protein–protein interactions are large
and generally flat.
RESULTS AND DISCUSSION
Conducting polymer sensor fabrication and
role of doped sample
The process to fabricate substrates with adherent
conducting polymer films resulted in a dip coating
polymer layer on the substrate surface (Figure 4).
While the conducting polymer grew a negatively
charged surface, the silane was a key to the
formation of a stable layer. Without the silane, the
films easily delaminated. In the presence of PA, the
polymer film presented an emerald green color
indicative of emeraldine salt. Previous studied
showed undoped sample had a conductivity of
5x10–4
S/cm and the highest conductivity of 109.04
S/cm was observed for the PA-doped sample
(Catedral, et al., 2004). The various electron states
in conducting polymers are in terms of the gap
between highest occupied molecular orbital
(HOMO) and lowest unoccupied molecular orbital
(LUMO) or the HOMO-LUMO energy gap
(Vardeny & Wei, 1998). The experimental values
of conductivity were found to exhibit roughly an
inverse correlation with the computed values of the
energy gap between the HOMO and LUMO; these
values have been reported by other researcher
groups (Atienza et al., 2004; Pascual, 2003). In this
way, the smallest HOMO-LUMO gap was
observed for the PA-doped sample, while the
biggest energy gaps were obtained for hydrochloric
acid and hydroiodide acid doped samples. The
HOMO-LUMO gap is the molecular counterpart of
the band gap for the macroscopic polymeric solid.
The PANI-ES samples with varying dopants
exhibit varying microstructures. Variation in
microstructure leads to different conductivities of
the samples. The addition of acid dopants alters the
polymer lattice, which leads to the ionization of
sites in the chains. The defects in the chain due to
the dopant ions provide the mobility of the charge
carriers on which conduction depends (Kroschwitz,
1988). The conductivity is also dependent on the
number of charge carriers. The undoped sample
displays globular but irregular morphology, where
PA-doped sample has coral-like structures with
elongated bodies (Catedral, et al., 2004). This
current investigation of the use of polymer
electronics is to find new methods of controlling its
properties electrochemically and is promising
routes toward harnessing the wide range of
potential uses of PANI.
UV-vis Spectroscopy of polyaniline
UV-vis absorbance spectra of the PA doped PANI
films were acquired with a UV-vis
spectrophotometer JASCO V-530. After creating
the baseline, films were inserted into the sample
holder, and the absorbance of sample was recorded
over the spectra from 200 nm to 1200 nm in steps
of 1 nm. The PA doped PANI samples (Figure 5)
exhibited two pronounced absorption bands in their
spectra. The broad band between 310 nm and 450
nm were attributed to the π –π* transition of the
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benzenoid ring (Ginder and Epstein., 1990;
McManus et.al, 1987; Stafstrom et.al 1987). The
other absorption band, at approximately 800 nm,
corresponded to a polaron interband transition
(Ginder and Epstein., 1990; McManus et.al, 1987;
Stafstrom et.al 1987). The presence of both these
absorptions indicated that our material was the
conducting salt form of PANI. Figure 4 presents
spectrum recorded for protonated (emeraldine salt,
green) PANI spot (from diluted PANI dispersion).
For this polymer layer, an absorption maximum
was observed at wavelength close to 770 nm and a
broad minimum in the range of 480 nm and 600
nm. The spectrum was also dependent on pH of
solution, where the spot was immersed; in PA
solution, deprotonated PANI changed its spectrum
to typical for protonated polymer. Typical spectra
of protonated PANI were recorded and neither
significant nor regular changes in the spectrum
were observed pointing to lack of chemical
reactions with the polymer. These results suggested
simple ion exchange equilibrium between the
polymer/dopant and solution, without noticeable
change of the polymer composition.
PANI-PA film morphology
During the polymerization of polyaniline in the
presence of PA was observed a short and thick rod
like structure (Tahir et al., 2005) which was similar
to one observed by (Abe et al. 1989). In general,
the polyaniline compounds synthesized with the
selected acids were shown to have a rod shape
structure. The PA-doped sample exhibited a coral-
like structure, (Catedral, et al., 2004). By using this
method a more stable coating and desired surface
can be created by adjusting the pH during
preparation. This method expects the similar
environment to control the polymer morphology,
where the dopant anions are inserted during
electrochemical polymerization method fulfilling
the request of electroneutrality. Therefore, their
concentrations are on the stoichiometric levels, for
it is reasonable that their presence have strong
influence on polyanilne morphology, conductivity,
and electrochemical activity and the polymerization
process itself (Arsov et al., 1998; Cordova et al,.
1994; Dhaoui et al., 2008; Koziel, 1993, 1995;
Lapkowski, 1990, 1993; Lippe & Holze, 1992;
Okamoto & Kotaka, 1998; Pron et al., 1992; Pron
& Rannou, 2002). Moreover, it was experimentally
confirmed that polyanilne obtained in the presence
of so called “large dopant anions”, originated from
hydrochloride acid, sulfuric acid, nitric acid, p-
toluensulfonic acid, and sulfosalicylic acid
promoted formation of more swollen and open
structured film, while the presence of “small ions”
such is ClO4
-
or BF4
-
, resulted in formation of a
more compact structure (Nunziante & Pistoria,
1989; Pruneanu et al., 1998; Zotti et al., 1988). The
order of the polyaniline growth was also proved to
increase with the size of the dopant anion (Inzelt et
al., 2000) but here we can also control the polymer
morphology by adjusting the pH during PA doped
PANI film preparation. Further investigation of the
morphology of samples will give a better
understanding of conductivity.
Lysozyme sensor
The sensitivity and selectivity of sensor were tested
and shown in Figure 6 and 7. It has been observed
that the potential of the Lys sensor changed
drastically with the addition of Lys before reaching
a stable value at the concentration of around 100
µg/mL, after which ΔE changed slowly. On the
other hand, by adding the BSA and thaumatin only
very slight potential response was observed. This
result indicated that the PA doped PANI electrode
based Lys sensor had little or no affinity to the
other protein molecules. This is consistent with the
sensing mechanism where Lys was initially
incorporated into the adsorbed film and extracted
away to create the molecular recognition cavity.
Moreover, the potential of the sensing electrode is
closely related to the charge of the protein, and the
net charge of the proteins is highly dependent on
the pH of the solution; the pH of the testing
medium is important to the response of the
electrode. The isoelectric point of the protein is
defined as the pH at which the net charge on the
protein surface is zero. Usually, in the solution
where pH is higher than the isoelectric point of the
protein, it is negatively charged, while in the media
with pH lower than its isoelectric point, the protein
is positively charged. In our experiment, the pH of
the buffer used as medium was 6.6 and 8.5. Our
aim was to see if the pH was the reason that
contributed to the insensitivity of the Lys sensor.
Further, pH 6.6 was chosen as the pH of the buffer
solution because polyaniline synthesized with PA
is shown to have the highest conductivity in a near
neutral solution. The characteristic of high
conductivity in a neutral solution is desirable to
accommodate the requirement for optimal
antibody-antigen reaction (Barbourand George,
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1997).The isoelectric point of Lys, BSA and
thaumatin are about 10.4, 4.6 and 12.7 respectively
(see table 1). Hence, in the above experimental
condition, the Lys showed to be more positively
charged and had good response at both pH but in
case of BSA and thaumatin the protein nature was
basic and acid, respectively, but did not show
noticeable response remaining still insensitive
towards both proteins. This result clearly excluded
the possibility that the insensitivity of the sensor to
other proteins was due to the zero net charge of the
target molecules or no domain-domain interactions.
Bovine serum albumin sensor
Similarly, the BSA sensing electrode was prepared
by exposed PA doped PANI film to the buffered
protein solutions of BSA overnight. Upon this
condition, a big potential response was shown by
the BSA while very slight or no response to Lys
and thaumatin shown in Figure 8 and 9. Since in
the practical application, target analyze usually
coexists with a large number of interfering species,
the sensor is expected to be able to identify a target
molecule. It means this electrode sensor have
ability to recognize a specific target even in the
multi-component system. The potential of the
sensor was plotted as a function of the
concentration and a big potential change was
observed with the addition of protein solution in
the initial state, which became constant after certain
concentration.
Response time of the sensor
The response time of the sensor was the time
needed for reaching a stable reading of the
potentiometer after a stepwise increase of the target
molecule concentration in 2–10 min.
Discussion about the binding/doped
mechanism factors
The mechanism of this method was based on the
involvement of covalent bindings as well as the
combination effect of other attractive forces
between the protein molecule and PA doped PANI
film surface. Moreover, the hydrogen bonding
between the hydrophilic groups of the protein
surface and the polymer chain as well as the
specific arrangement of these interactions in shape
and orientation, determined the recognition and
selectivity of the sensor (Shi et al., 1999; Kaufman
et al., 2007). Although the sensor was
demonstrated to work well with the proteins tested
so far, but still a question remains to answer: how
important is geometric match between sensing
molecules and sensor to function properly? The
sensitivity of the sensor to the similar protein
molecules indicates the geometrical
complementarity is crucial to function properly.
Even though the different protein molecules can
have the domain-domain interactions, two possible
processes may prevent them from inducing an
electrochemical signal. Firstly, the protein
molecule tightly adsorbed on the electrode surface
may be denatured quickly because of surrounding
environment and hence loses its electrochemical
activity. Secondly, the loosely attached protein
molecules that do not have hydrogen bonds with
the electrode surface have a bigger chance to
escape into the solutions instead of staying in the
monolayer matrix, so that the adsorption is unstable
because of kinetic reasons. Since the potential of
the sensing electrode is closely related to the
amount of charges on the electrode surface, the less
accumulated charges due to the escaping of the
approached molecules into the solution will lead to
an unchanged potential of the sensing electrode.
Additionally, the best potentiometric response was
achieved at high protein concentration due to
maximum mass of protein on the electrode surface
which results maximum binding capacity of the
electrode surface. When the polymer backbone of
film interacted with protein, the potentiometric
response not only depended on the concentration of
protein being bound to the surface but also on the
nature of the protein used. For example, the protein
with higher molecular weight shows less change in
potentiometric response. It could be because of
steric hindrance as overcrowding of protein may
have blocked the access of substrate to protein
located closer to the electrode surface. In this work,
we observed that the potentiometric response of
different protein were different and it was restricted
by the molecular weight of protein and to noted
less change in potentiometric response to huge
protein (protein having high molecular weight such
as BSA and thaumatin). Moreover, the electronic
state of the PA doped PANI films also changed
significantly after protein exposure in the presence
of BSA and Lys with different pH of buffer
solution. The pH-controlled of buffer solution
during the experiment provided enormous
flexibility to control molecular organization,
composition as well as the surface properties of PA
doped PANI film. In the experiment, all the work
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was done at two different pH. As we know,
electrostatic and non-electrostatic interactions are
related to pH phenomena. So that the biopolymers
which had isoelectric point less than pH 7 acted as
basic and were ruled by non-electrostatic
interactions, for example in the case of BSA. On
the other hand the biopolymer like Lys which had
isoelectric point of 11 acted as an acid at pH 7 and
was ruled by electrostatic interactions. Here, we
report the pH dependence of the oxidation/dopant
states of PANI. Our studies also indicated that the
electroactivity of PANI was stable at pH 8.5.
Figure 1: PANI form
Figure 2: Experiment set up for the preparation of PA doped PANI film
Figure: 3 Inferring domain-domain interactions from protein-protein interactions
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Figure 4. PA doped PANI film
Figure 5: UV spectroscopy graph of PA doped PANI film
Table: 1 Protein nature and its behavior at pH 6.6 & 8.5 with comparision of PA doped PANI
Figure 6: Potentiometric response of Lysozyme sensor at pH 6.6
Graph is ΔE (mV) vs Concentration (µg/mL) (y axis vs x-axis )
Protein Molecular
weight (kD)
Isoelectric
point
Protein
Nature at
pH 6.6
Protein
Nature at
pH 8.5
PANI-PA film behaviour
Lysozyme 14400 10.4 Acidic Less Acidic Better at pH 6.6 but also
show good electroactivity at
pH 8.5
Bovine serum
albumin
67000 4.6 Neutral More Neutral Better at pH 6.6
Thaumatin 22000 12 More Acidic Less Acidic Better at pH 8.5 where less
acidic environment
ΔE (mV)
Concentration (µg/mL)
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Figure 7: Potentiometric response of Lysozyme sensor at pH 8.5
Figure 8: Potentiometric response of Bovine serum alumina (BSA) sensor at pH 6.6
Figure 9: Potentiometric response of Bovine serum albumin (BSA) sensor at pH 8.5
(mV)
ΔE
(mV)
(µg/mL)
Concentration
(µg/mL)
ΔE
(mV)
Concentration
(µg/mL)
ΔE
Concentration
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CONCLUSIONS
In this study, a protein sensor was built by a novel
conducting polymer sensing mechanism, utilizing
the interaction between charged functional moieties
of a target protein and the complexation between
the PANI and the dopant molecule. This process
was demonstrated to be efficient in recognizing Lys
and BSA. The selective adsorption of the target
protein molecules onto the sensing electrode
induced a significant potential change of the
electrode and this change became more gradual
above a certain concentration due to saturation of
the accepting sites. The sensor also had better
ability to recognize the specific protein-protein
interaction. The size and shape match was
demonstrated to be crucial for the precise
recognition. The results obtained in this research
work indicated the ability of the synthesized PA
doped PANI film to act as a biomolecular sensor at
physiological pH. We aim to do further studies
which will be keen on assessing other
polymerization approaches and other protonic acids
to increase conductivity and solubility of
polyaniline at neutral pH. One potential manner
would be to integrate sulphonate groups onto the
polymer backbone. The addition of dopant, for
example polyvinyl sulphonate, was presented to
enhance conductivity of polyaniline at neutral pH.
The water solubility of polyaniline synthesized
from the projected way so far required to be
examined. Research on the influence of the
polymerization temperature below 0 ◦
C and its
corresponding a macromolecular sensor
performance will examined too.
ACKNOWLEDGMENT
This project is supported by PhD student Research
Grant of the University of Genova
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