This document summarizes an experiment comparing pure gelatin hydrogel to microbially transglutaminase (mTG) cross-linked gelatin hydrogel. Rheology tests showed the cross-linked hydrogel had a higher elastic modulus, indicating stronger structure, but surprisingly broke down at a lower shear stress than pure gelatin. Absorbency tests found the cross-linked hydrogel absorbed water more slowly, likely due to decreased pore size from cross-linking. Release of dye from the hydrogels showed the cross-linked hydrogel retained its structure at body temperature and released dye more slowly in water than ethanol, suggesting potential as an extended drug delivery system.
This study optimized gelatin and microbial transglutaminase (mTg) hydrogels for use as cardiac tissue engineering scaffolds. Various concentrations of gelatin and mTg were tested by measuring hydrogel mass changes after incubation. Hydrogels with mTg crosslinker showed less mass change, demonstrating mTg's role in stability. The optimal gelatin and mTg concentrations were found to develop biomimetic hydrogel scaffolds for growing cardiomyocytes.
This document summarizes research on the hydrodynamic properties of gelatin. Gelatin is obtained through partial hydrolysis of collagen, the main structural protein in skin and bone. Intrinsic viscosity measurements were taken of gelatin solutions at varying temperatures to determine properties like molecular weight and shape. The results showed that gelatin exhibits random coil shapes in solution and undergoes a coil-to-helix transition below 35°C. Intrinsic viscosity was found to decrease with increasing temperature, reflecting a decrease in intermolecular interactions. These findings provide insight into gelatin's behavior in industrial processes and food applications.
IOSRPHR(www.iosrphr.org) IOSR Journal of Pharmacyiosrphr_editor
This document summarizes a study investigating the dielectric and spectroscopic properties of amorphous captopril, an orally active drug used to treat hypertension. Differential scanning calorimetry showed captopril is a non-crystallizing compound with a glass transition temperature of 273.91K. Fourier transform infrared spectroscopy showed hydrogen bonding is stronger in the amorphous state than the crystalline state. Broadband dielectric spectroscopy revealed molecular mobility is present even in the glassy state below the glass transition temperature, which could contribute to instability. The fragility value of 84 indicates captopril is a fragile glassformer, which are often physically unstable. The study aimed to understand factors influencing instability of the amorphous drug form.
This document describes the development of a high content screening assay to evaluate the effects of degradation products from gelatin-based biomaterials on osteoclast differentiation. The assay uses the murine monocytic cell line RAW 264.7, which can differentiate into osteoclasts. Degradation products from six different gelatin-lysine diisocyanate hydrogel compositions were tested in the assay. The degradation products were found to inhibit the formation of multinucleated osteoclasts, suggesting they may support bone regeneration by suppressing bone resorption. The assay provides a way to quantitatively assess biomaterial effects on osteoclast fusion and differentiation in a high throughput manner.
A Novel Polymeric Prodrugs Synthesized by Mechanochemical Solid-State Copolym...inventionjournals
:We developed the novel polymeric prodrugs synthesized by mechanochemical solid-state copolymerization of glucose-based polysaccharides (dextran orglycogen) and the methacryloyloxy derivative of 5-fluorouracil (5-FU). The copolymerization proceededreadily and each polymeric prodrug was quantitatively obtained within8 h reaction. The number average molecular weight (Mn) and polydispersity (H) of the polymeric prodrug synthesized from dextran was 24,000 g/mol and 5.10, respectively. The number average particle diameter of the polymeric prodrug derived from glycogen was 14.9 nm. The hydrolysis profiles of the polymeric prodrug synthesized from dextranapparently followed the first-order kinetics, and 100% drug release was observed under the experimental condition used. The polymeric prodrug derived from glycogen also continued to release 5-FU at the first-order rate up to 5 h, followed by its rate constant decreased gradually. These results suggest that lower accessibility of water molecules for the synthetic polymer chains inside the glycogen particle might cause the gradual decrease of drug release rate.
Hydrogels introduction and applications in biology and enAndrew Simoi
Hydrogels are water-swollen, crosslinked polymers that can absorb large amounts of water. They have a variety of applications including in soft contact lenses, drug delivery, wound healing, and tissue engineering. Hydrogels are advantageous for tissue engineering and cell culture as they can mimic extracellular matrix, provide structural support, and allow for nutrient transport. They are also useful for drug delivery as they allow controlled release of molecules. The document discusses the properties, types, advantages and uses of hydrogels.
Stability studies ensuring the maintenance of product quality, safety and efficacy throughout the shelf life are considered as pre-requisite for the acceptance and approval of any pharmaceutical product. Stability testing is a routine procedure performed on drug substances and products and is employed at various stages of the product development.
This study optimized gelatin and microbial transglutaminase (mTg) hydrogels for use as cardiac tissue engineering scaffolds. Various concentrations of gelatin and mTg were tested by measuring hydrogel mass changes after incubation. Hydrogels with mTg crosslinker showed less mass change, demonstrating mTg's role in stability. The optimal gelatin and mTg concentrations were found to develop biomimetic hydrogel scaffolds for growing cardiomyocytes.
This document summarizes research on the hydrodynamic properties of gelatin. Gelatin is obtained through partial hydrolysis of collagen, the main structural protein in skin and bone. Intrinsic viscosity measurements were taken of gelatin solutions at varying temperatures to determine properties like molecular weight and shape. The results showed that gelatin exhibits random coil shapes in solution and undergoes a coil-to-helix transition below 35°C. Intrinsic viscosity was found to decrease with increasing temperature, reflecting a decrease in intermolecular interactions. These findings provide insight into gelatin's behavior in industrial processes and food applications.
IOSRPHR(www.iosrphr.org) IOSR Journal of Pharmacyiosrphr_editor
This document summarizes a study investigating the dielectric and spectroscopic properties of amorphous captopril, an orally active drug used to treat hypertension. Differential scanning calorimetry showed captopril is a non-crystallizing compound with a glass transition temperature of 273.91K. Fourier transform infrared spectroscopy showed hydrogen bonding is stronger in the amorphous state than the crystalline state. Broadband dielectric spectroscopy revealed molecular mobility is present even in the glassy state below the glass transition temperature, which could contribute to instability. The fragility value of 84 indicates captopril is a fragile glassformer, which are often physically unstable. The study aimed to understand factors influencing instability of the amorphous drug form.
This document describes the development of a high content screening assay to evaluate the effects of degradation products from gelatin-based biomaterials on osteoclast differentiation. The assay uses the murine monocytic cell line RAW 264.7, which can differentiate into osteoclasts. Degradation products from six different gelatin-lysine diisocyanate hydrogel compositions were tested in the assay. The degradation products were found to inhibit the formation of multinucleated osteoclasts, suggesting they may support bone regeneration by suppressing bone resorption. The assay provides a way to quantitatively assess biomaterial effects on osteoclast fusion and differentiation in a high throughput manner.
A Novel Polymeric Prodrugs Synthesized by Mechanochemical Solid-State Copolym...inventionjournals
:We developed the novel polymeric prodrugs synthesized by mechanochemical solid-state copolymerization of glucose-based polysaccharides (dextran orglycogen) and the methacryloyloxy derivative of 5-fluorouracil (5-FU). The copolymerization proceededreadily and each polymeric prodrug was quantitatively obtained within8 h reaction. The number average molecular weight (Mn) and polydispersity (H) of the polymeric prodrug synthesized from dextran was 24,000 g/mol and 5.10, respectively. The number average particle diameter of the polymeric prodrug derived from glycogen was 14.9 nm. The hydrolysis profiles of the polymeric prodrug synthesized from dextranapparently followed the first-order kinetics, and 100% drug release was observed under the experimental condition used. The polymeric prodrug derived from glycogen also continued to release 5-FU at the first-order rate up to 5 h, followed by its rate constant decreased gradually. These results suggest that lower accessibility of water molecules for the synthetic polymer chains inside the glycogen particle might cause the gradual decrease of drug release rate.
Hydrogels introduction and applications in biology and enAndrew Simoi
Hydrogels are water-swollen, crosslinked polymers that can absorb large amounts of water. They have a variety of applications including in soft contact lenses, drug delivery, wound healing, and tissue engineering. Hydrogels are advantageous for tissue engineering and cell culture as they can mimic extracellular matrix, provide structural support, and allow for nutrient transport. They are also useful for drug delivery as they allow controlled release of molecules. The document discusses the properties, types, advantages and uses of hydrogels.
Stability studies ensuring the maintenance of product quality, safety and efficacy throughout the shelf life are considered as pre-requisite for the acceptance and approval of any pharmaceutical product. Stability testing is a routine procedure performed on drug substances and products and is employed at various stages of the product development.
This document describes research on novel ultra-short peptide sequences containing tryptophan and arginine residues that show potent antibacterial activity against drug-resistant Staphylococcus aureus. Key findings include:
1) The peptide sequences were modified with N-terminal aromatic tags to induce self-assembly into nanovesicles around 140-190 nm in diameter.
2) The nanovesicles have a positively charged surface and hydrophobic core containing tryptophan residues and N-terminal tags.
3) Experiments showed the peptide nanovesicles kill bacteria by disrupting their membranes, causing membrane depolarization and leakage of intracellular contents.
4) The self-assembled nanostructure is believed to
The effect of conjugation on different polymers in bioadhesive films of losartanSriramNagarajan18
The document summarizes a study that investigated the effect of conjugating different polymers on the properties of buccal films containing the drug losartan potassium. Sodium alginate and chitosan were conjugated with cysteine and thioglycolic acid respectively, and films containing plain or conjugated polymers were prepared and evaluated. The conjugation was confirmed using FTIR and the polymers were found to contain thiol groups. Films were evaluated for properties like thickness, drug content, swelling, bioadhesion and drug permeation. Formulations containing conjugated polymers showed higher bioadhesion, swelling and longer drug permeation compared to films with plain polymers. The optimized formulations were found to be stable.
The student synthesized demethylated curcumin to create a derivative that is more soluble in aqueous solutions than curcumin. Demethylation was achieved through a reaction involving aluminum trichloride and hydrochloric acid. While NMR analysis indicated partial demethylation occurred, results were unclear due to overlapping peaks from impurities. In the future, the student aims to test the synthesized compound's ability to disaggregate beta amyloid plaques compared to curcumin.
POLYMERS IN SOLID STATE, PHARMACEUTICAL APPLICATIONS OF POLYMERS AND RECENT A...Priyanka Modugu
A description on polymers in solid state, solid state properties of polymers, mechanical properties of polymers, heat of crystallization & fusion, thermodynamics of fusion & crystallization, pharmaceutical applications of polymers and recent advances in the use of polymers for drug delivery system
This document summarizes a presentation about polysaccharide hydrogels and their applications. It discusses how polysaccharides can be used to form hydrogels through various methods like ionotropic gelation or chemical cross-linking. It then outlines several biomedical applications of polysaccharide hydrogels, including for drug and protein delivery, tissue engineering, dental applications, and heritage protection. The document also discusses using polysaccharide nanohydrogels for controlled drug delivery and how they can be loaded with various drugs and biological agents.
This document provides an overview of preformulation studies, which characterize the physical and chemical properties of new drug molecules to aid in the development of safe, effective, and stable dosage forms. Some key points covered include:
- Preformulation studies give direction for dosage form selection, excipient choice, composition, and process development.
- Important physicochemical properties to determine include solubility, partition coefficient, pKa, stability, and interactions with excipients.
- Methods are described for evaluating properties like solubility, dissolution, oxidation, hydrolysis, and polymorphism which can impact stability and bioavailability.
- Understanding these properties aids in developing robust formulations and setting appropriate storage conditions for drug products
Preformulation studies for bulk characterizationmangu3107
The document discusses preformulation studies, which generate information to help formulate stable and effective drug dosage forms. The overall goals of preformulation are to improve drug stability, bioavailability, and reduce incompatibility. Some key tests described include determining the drug's physical properties like color, odor, taste, purity, and thermal behavior. Melting point analysis can provide information on a drug's identity and purity. Preformulation studies are important to identify suitable drug candidates and formulations before clinical development.
This presentation provides basics of self healing polymers along with all the different types of polymers and mechanisms involved including a focus on new extrinsic and intrinsic technologies.It also discusses the applications of self healing polymers
This document discusses key concepts in preformulation testing. It begins by defining preformulation as investigating the physical and chemical properties of a drug substance alone and combined with excipients. The overall goal is to generate information useful for developing stable and safe dosage forms.
It then outlines some of the main steps in preformation process including assessing organoleptic properties, purity, particle size, melting point, stability, excipient compatibility, solubility, polymorphism, pH and salt formation. Specific tests are mentioned for many of these areas.
The document emphasizes that preformulation is important for aiding drug candidate selection, product design, decreasing time to market, and ensuring overall safety and efficacy of the final product
This document discusses preformulation and various analytical techniques used for drug-excipient compatibility studies. It describes types of incompatibilities like physical and chemical incompatibilities. Techniques discussed include thermal analysis methods like thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Other techniques mentioned are X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The document also covers limitations of thermal analysis and applications of these techniques in preformulation studies like characterization of hydrates/solvates, detection of impurities, and compatibility studies.
The document discusses various techniques for improving the solubility and dissolution rate of poorly soluble drug compounds. It defines key terms like solubility, polymorphism, and solid dispersions. It describes three main methods for creating solid dispersions - hot melt method, solvent evaporation method, and hot melt extrusion. These methods aim to molecularly disperse the drug in an inert carrier in order to enhance solubility. The document also discusses other techniques like amorphous forms, solvates, and eutectic mixtures that can improve drug properties.
Wound healing is an important concern these days and there are lots of various medications for it.
One of the most effective methods is Applying Acellular Matrices to the wound bed.
In this presentation, It was tried to explain the application of these products as well as the complications of usage.
I wish it be useful for anyone.
It would be appreciated if you let me know your comments on my presentation.
sincerely,
S. Mohammad Zargar
Contact me: s.mohammad.zargar@gmail.com
The document provides an overview of preformulation studies. It discusses the importance of characterizing the physical and chemical properties of new drug molecules during preformulation to aid in the development of stable dosage forms. Some of the key areas covered include drug-excipient compatibility studies, stability kinetics testing, and determining properties like solubility, partition coefficient, and polymorphism that can help dictate the suitable dosage form. The goal of preformulation is to gather necessary data to rationally develop safe and efficacious dosage forms.
IRJET- Study of Compressive Strength of Self Healing ConcreteIRJET Journal
This document studies the compressive strength of self-healing concrete that uses bacteria solution in place of water. Cubes of concrete with different percentages of bacteria solution (0%, 30%, 50%, 70%, 100%) in place of water were tested. Results showed compressive strength increased up to 70% bacteria solution, but decreased at 100%. At 28 days, concrete with 70% bacteria solution had the highest compressive strength at 33.95 MPa, an increase of 25% over normal concrete. The bacteria may increase strength by filling pores and precipitating calcium carbonate through microbiologically induced calcium carbonate precipitation.
The document discusses preformulation studies for solids. The objectives are to develop a stable, safe and effective dosage form with maximum bioavailability. Preformulation testing characterizes the physical, chemical and other properties of a new drug to aid in dosage form development. Studies include analyzing the drug's crystallinity, polymorphism, particle size, solubility, stability and compatibility with excipients. Analytical techniques used include microscopy, spectroscopy, chromatography and thermal analysis to understand the drug's properties and develop an optimal dosage form.
IN VITRO EVALUATION OF CYTOTOXIC ACTIVITY OF HYDRAZIDEHYDRAZONES BASED ON 4-C...Dimo Angelov
Two new coumarin-based hydrazide/hydrazones were synthesized and evaluated for their cytotoxicity against two chronic lymphocytic leukemia cell lines. Both compounds showed strong cytotoxicity, with IC50 values several times lower than the reference drug bendamustine. Exposure to the compounds induced fragmentation of leukemic cell nuclei, a hallmark of apoptosis. Quantification assays further confirmed the compounds induced apoptosis in the leukemia cells. The results indicate the new hydrazide/hydrazones have more potent antileukemic effects in vitro compared to bendamustine.
This document discusses several key areas of preformulation research for new drug candidates. These include analyzing organoleptic properties like color, odor and taste; bulk characterization of crystallinity, polymorphism and particle size; powder flow properties; solubility analysis including pH solubility profiles, partition coefficients and dissolution; and stability studies of solutions and solids, including compatibility with excipients. The goal of preformulation research is to better understand the physical and chemical properties of new drug substances to guide successful formulation development and scale-up of drug products.
This study analyzed the impact of temperature variation and inhibitors on succinate dehydrogenase (SDH) activity in liver tissue. SDH activity was highest at 37°C and lowest at 19°C, showing enzyme denaturation at extreme temperatures. Malonate inhibited SDH competitively at low concentrations and non-competitively at high concentrations. Nicotinamide adenine dinucleotide (NAD+) increased SDH activity when combined with its substrate succinate, demonstrating the coenzyme role of NAD+ in the Krebs cycle reaction catalyzed by SDH. The results reflected the temperature and cofactor dependencies of enzymatic reactions in living organisms.
Pragmatismo e Padroes - Um limiar tenue entre o sucesso e o fracasso do seu p...Klederson Bueno
Klederson Bueno é um arquiteto de sistemas, desenvolvedor e evangelista PHP. Ele discute princípios de arquitetura de software limpo e SOLID, padrões de projeto como MVC e iterador, e abordagens ágeis como MVP e Scrum. Klederson também fala sobre a importância da legibilidade, testabilidade, manutenibilidade e reusabilidade no desenvolvimento de software.
The document discusses critical success factors in software projects, noting that 26% of projects fail and 46% experience cost or schedule overruns or loss of functionality. It identifies common reasons for failures as including unclear user needs, scope, change management, technology changes, business needs changes, unrealistic deadlines, resistant users, and lost sponsorship. The document recommends managing expectations, skills, quality, and progress, making sustainable choices, and performing a post-mortem review after every project to identify lessons learned and improve future projects.
This document describes research on novel ultra-short peptide sequences containing tryptophan and arginine residues that show potent antibacterial activity against drug-resistant Staphylococcus aureus. Key findings include:
1) The peptide sequences were modified with N-terminal aromatic tags to induce self-assembly into nanovesicles around 140-190 nm in diameter.
2) The nanovesicles have a positively charged surface and hydrophobic core containing tryptophan residues and N-terminal tags.
3) Experiments showed the peptide nanovesicles kill bacteria by disrupting their membranes, causing membrane depolarization and leakage of intracellular contents.
4) The self-assembled nanostructure is believed to
The effect of conjugation on different polymers in bioadhesive films of losartanSriramNagarajan18
The document summarizes a study that investigated the effect of conjugating different polymers on the properties of buccal films containing the drug losartan potassium. Sodium alginate and chitosan were conjugated with cysteine and thioglycolic acid respectively, and films containing plain or conjugated polymers were prepared and evaluated. The conjugation was confirmed using FTIR and the polymers were found to contain thiol groups. Films were evaluated for properties like thickness, drug content, swelling, bioadhesion and drug permeation. Formulations containing conjugated polymers showed higher bioadhesion, swelling and longer drug permeation compared to films with plain polymers. The optimized formulations were found to be stable.
The student synthesized demethylated curcumin to create a derivative that is more soluble in aqueous solutions than curcumin. Demethylation was achieved through a reaction involving aluminum trichloride and hydrochloric acid. While NMR analysis indicated partial demethylation occurred, results were unclear due to overlapping peaks from impurities. In the future, the student aims to test the synthesized compound's ability to disaggregate beta amyloid plaques compared to curcumin.
POLYMERS IN SOLID STATE, PHARMACEUTICAL APPLICATIONS OF POLYMERS AND RECENT A...Priyanka Modugu
A description on polymers in solid state, solid state properties of polymers, mechanical properties of polymers, heat of crystallization & fusion, thermodynamics of fusion & crystallization, pharmaceutical applications of polymers and recent advances in the use of polymers for drug delivery system
This document summarizes a presentation about polysaccharide hydrogels and their applications. It discusses how polysaccharides can be used to form hydrogels through various methods like ionotropic gelation or chemical cross-linking. It then outlines several biomedical applications of polysaccharide hydrogels, including for drug and protein delivery, tissue engineering, dental applications, and heritage protection. The document also discusses using polysaccharide nanohydrogels for controlled drug delivery and how they can be loaded with various drugs and biological agents.
This document provides an overview of preformulation studies, which characterize the physical and chemical properties of new drug molecules to aid in the development of safe, effective, and stable dosage forms. Some key points covered include:
- Preformulation studies give direction for dosage form selection, excipient choice, composition, and process development.
- Important physicochemical properties to determine include solubility, partition coefficient, pKa, stability, and interactions with excipients.
- Methods are described for evaluating properties like solubility, dissolution, oxidation, hydrolysis, and polymorphism which can impact stability and bioavailability.
- Understanding these properties aids in developing robust formulations and setting appropriate storage conditions for drug products
Preformulation studies for bulk characterizationmangu3107
The document discusses preformulation studies, which generate information to help formulate stable and effective drug dosage forms. The overall goals of preformulation are to improve drug stability, bioavailability, and reduce incompatibility. Some key tests described include determining the drug's physical properties like color, odor, taste, purity, and thermal behavior. Melting point analysis can provide information on a drug's identity and purity. Preformulation studies are important to identify suitable drug candidates and formulations before clinical development.
This presentation provides basics of self healing polymers along with all the different types of polymers and mechanisms involved including a focus on new extrinsic and intrinsic technologies.It also discusses the applications of self healing polymers
This document discusses key concepts in preformulation testing. It begins by defining preformulation as investigating the physical and chemical properties of a drug substance alone and combined with excipients. The overall goal is to generate information useful for developing stable and safe dosage forms.
It then outlines some of the main steps in preformation process including assessing organoleptic properties, purity, particle size, melting point, stability, excipient compatibility, solubility, polymorphism, pH and salt formation. Specific tests are mentioned for many of these areas.
The document emphasizes that preformulation is important for aiding drug candidate selection, product design, decreasing time to market, and ensuring overall safety and efficacy of the final product
This document discusses preformulation and various analytical techniques used for drug-excipient compatibility studies. It describes types of incompatibilities like physical and chemical incompatibilities. Techniques discussed include thermal analysis methods like thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Other techniques mentioned are X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The document also covers limitations of thermal analysis and applications of these techniques in preformulation studies like characterization of hydrates/solvates, detection of impurities, and compatibility studies.
The document discusses various techniques for improving the solubility and dissolution rate of poorly soluble drug compounds. It defines key terms like solubility, polymorphism, and solid dispersions. It describes three main methods for creating solid dispersions - hot melt method, solvent evaporation method, and hot melt extrusion. These methods aim to molecularly disperse the drug in an inert carrier in order to enhance solubility. The document also discusses other techniques like amorphous forms, solvates, and eutectic mixtures that can improve drug properties.
Wound healing is an important concern these days and there are lots of various medications for it.
One of the most effective methods is Applying Acellular Matrices to the wound bed.
In this presentation, It was tried to explain the application of these products as well as the complications of usage.
I wish it be useful for anyone.
It would be appreciated if you let me know your comments on my presentation.
sincerely,
S. Mohammad Zargar
Contact me: s.mohammad.zargar@gmail.com
The document provides an overview of preformulation studies. It discusses the importance of characterizing the physical and chemical properties of new drug molecules during preformulation to aid in the development of stable dosage forms. Some of the key areas covered include drug-excipient compatibility studies, stability kinetics testing, and determining properties like solubility, partition coefficient, and polymorphism that can help dictate the suitable dosage form. The goal of preformulation is to gather necessary data to rationally develop safe and efficacious dosage forms.
IRJET- Study of Compressive Strength of Self Healing ConcreteIRJET Journal
This document studies the compressive strength of self-healing concrete that uses bacteria solution in place of water. Cubes of concrete with different percentages of bacteria solution (0%, 30%, 50%, 70%, 100%) in place of water were tested. Results showed compressive strength increased up to 70% bacteria solution, but decreased at 100%. At 28 days, concrete with 70% bacteria solution had the highest compressive strength at 33.95 MPa, an increase of 25% over normal concrete. The bacteria may increase strength by filling pores and precipitating calcium carbonate through microbiologically induced calcium carbonate precipitation.
The document discusses preformulation studies for solids. The objectives are to develop a stable, safe and effective dosage form with maximum bioavailability. Preformulation testing characterizes the physical, chemical and other properties of a new drug to aid in dosage form development. Studies include analyzing the drug's crystallinity, polymorphism, particle size, solubility, stability and compatibility with excipients. Analytical techniques used include microscopy, spectroscopy, chromatography and thermal analysis to understand the drug's properties and develop an optimal dosage form.
IN VITRO EVALUATION OF CYTOTOXIC ACTIVITY OF HYDRAZIDEHYDRAZONES BASED ON 4-C...Dimo Angelov
Two new coumarin-based hydrazide/hydrazones were synthesized and evaluated for their cytotoxicity against two chronic lymphocytic leukemia cell lines. Both compounds showed strong cytotoxicity, with IC50 values several times lower than the reference drug bendamustine. Exposure to the compounds induced fragmentation of leukemic cell nuclei, a hallmark of apoptosis. Quantification assays further confirmed the compounds induced apoptosis in the leukemia cells. The results indicate the new hydrazide/hydrazones have more potent antileukemic effects in vitro compared to bendamustine.
This document discusses several key areas of preformulation research for new drug candidates. These include analyzing organoleptic properties like color, odor and taste; bulk characterization of crystallinity, polymorphism and particle size; powder flow properties; solubility analysis including pH solubility profiles, partition coefficients and dissolution; and stability studies of solutions and solids, including compatibility with excipients. The goal of preformulation research is to better understand the physical and chemical properties of new drug substances to guide successful formulation development and scale-up of drug products.
This study analyzed the impact of temperature variation and inhibitors on succinate dehydrogenase (SDH) activity in liver tissue. SDH activity was highest at 37°C and lowest at 19°C, showing enzyme denaturation at extreme temperatures. Malonate inhibited SDH competitively at low concentrations and non-competitively at high concentrations. Nicotinamide adenine dinucleotide (NAD+) increased SDH activity when combined with its substrate succinate, demonstrating the coenzyme role of NAD+ in the Krebs cycle reaction catalyzed by SDH. The results reflected the temperature and cofactor dependencies of enzymatic reactions in living organisms.
Pragmatismo e Padroes - Um limiar tenue entre o sucesso e o fracasso do seu p...Klederson Bueno
Klederson Bueno é um arquiteto de sistemas, desenvolvedor e evangelista PHP. Ele discute princípios de arquitetura de software limpo e SOLID, padrões de projeto como MVC e iterador, e abordagens ágeis como MVP e Scrum. Klederson também fala sobre a importância da legibilidade, testabilidade, manutenibilidade e reusabilidade no desenvolvimento de software.
The document discusses critical success factors in software projects, noting that 26% of projects fail and 46% experience cost or schedule overruns or loss of functionality. It identifies common reasons for failures as including unclear user needs, scope, change management, technology changes, business needs changes, unrealistic deadlines, resistant users, and lost sponsorship. The document recommends managing expectations, skills, quality, and progress, making sustainable choices, and performing a post-mortem review after every project to identify lessons learned and improve future projects.
Velcom ERP IT Sourcing Pvt Ltd is an independent ERP consulting and talent sourcing company with over 2000 person-months of experience implementing ERP, SCM, CRM and BI projects. It assists clients in selecting vendors and implementing ERP solutions to minimize risks and maximize success. Velcom has expertise in solutions from SAP, Oracle, Microsoft and others and helps clients achieve their goals on time and under budget.
Critical Success Factors for designing & sustaining technology-enhanced T&L p...2016
Critical success factors for designing and sustaining a technology-enhanced learning tool include ensuring the system has: low barriers to entry through easy installation and use with little required learning; robust technology requiring almost no maintenance that scales across devices and provides mobile access; and adds value through improving the learning process, combating information overload, and increasing the quality of information.
This document discusses the challenges of global projects and success factors. Some challenges include cultural differences, languages, business practices, and time zones across countries. Success requires disciplined planning, thorough risk assessment, engagement of all locations, understanding that the front end is global but back end local, and extensive testing. Key factors are detailed dynamic plans, clear milestones, buffer time, 24/7 support during deployment, exhaustive contact lists, and post implementation support.
10 critical factors for success of a projectZilicus
The document outlines 10 critical factors for project success: 1) Keeping projects simple through clear objectives and communication. 2) The project manager is ultimately responsible for delivery. 3) Reinforcing focus through organizational prioritization and strong support. 4) Setting specific and quantifiable objectives. 5) Developing a clear and detailed project plan. 6) Maintaining the project scope. 7) Building an inspired project team. 8) Effective issue management. 9) Risk planning and mitigation. 10) Agreeing on a point of closure for the project. The key is transparent communication with all stakeholders.
Critical success factors in e-Governance projectsMukund Nadgowda
This presentation narrates various critical success factors in e-Governance projects (particularly in the Indian scenario). The presentation is shared with a hope that it turns out to be a useful guide to students / seekers in the e-Governance sector.
- The document summarizes a research study that examined how the concentration of curcumin solution and type of solvent (ethanol/water mixture) affects the loading and encapsulation efficiency of curcumin in silk fibroin and gelatin hydrogels.
- Hydrogels made of different ratios of silk fibroin and gelatin were loaded with curcumin dissolved in solutions of varying concentrations (1, 2, 4 mg/ml) and solvent mixtures (100% ethanol, 90% ethanol/10% water, 80% ethanol/20% water).
- The loading and encapsulation efficiency of curcumin in the hydrogels was evaluated to determine the optimal parameters but no definitive conclusions could be drawn
Chemical and Physical properties of Cassava Starch-Cm-Chitosan-Acrylic Acid Hydrogel prepared from radiation –induced crosslinking
Gatot Trimulyadi Rekso
Center for Application of Isotopes and Radiation- National Nuclear Energy Agency
Jl. Lebak Bulus Raya No. 49, Jakarta-Selatan, Indonesia
Corresponding author; e-mail; gatot2811@yahoo.com ,
Fax: +62-21-.7513270, HP ; 08129419442
Design, Synthesis, and 3D Fabrication of Novel Nutraceutical Hydrogels to Rep...Charles Malcolm Roberson
The document describes research into developing novel hydrogel scaffolds for cartilage repair. The hydrogels are synthesized from poly(N-vinylcaprolactam) and hyaluronic acid, and functionalized with nutraceuticals. Initial studies showed cross-linked hydrogels provided more robust structures for 3D printing geometric shapes encapsulated with cartilage cells. Further studies aim to investigate how nutraceuticals in the hydrogels protect cartilage cells from oxidative stress and improve extracellular matrix protein synthesis.
Effect of addition of polyethylene glycol (peg) as plasticizer on edible film...Nabila298243
Gelatin is a type of protein extracted from animal collagen tissue found in animal skin, bones and ligaments or connective tissue. Gelatin has high digestibility properties therefore it has the potential to be the raw material for making edible films. The edible film is a thin layer produced from edible materials. Edible films can be formed from three types of constituent materials, such as hydrocolloids, lipids, and mixtures/composites of the two. Several types of hydrocolloids that are able to make edible films are proteins (gelatin). The test parameters include tensile strength, elongation, thickness, water vapour transmission rate, moisture content and amino acid profile. PEG in edible films is a useful plasticizer to reduce the stiffness of the polymer. The best edible film from milkfish skin gelatin was obtained at a concentration of 1% polyethylene glycol plasticizer with physicochemical characteristics including tensile strength of 11.94 MPa, elongation of 2.55%, thickness of 0.10 mm, water vapour transmission rate of 159.36 g/m2/day and water content of 16.03% with the highest amino acid content, namely Glycine at 172021.41 mg/kg and the lowest, namely L-Tyrosine at 4333.40 mg/kg.
Characterization of Semi-Interpenetrated Network Alginate/Gelatin Wound Dress...UniversitasGadjahMada
Gel contraction of alginate during ionic crosslinking at sol phase was reduced by blending with gelatin solution due to intermolecular interaction and chain entanglement. The semi-interpenetrated network (semi-IPN) of wound dressing hydrogels were prepared by overlaid alginate/gelatin blend with 1.0% (w/w) CaCl2 solution under ambient temperature for 2 h. Results showed that gel contraction was significantly reduced with increasing gelatin content i.e. from 40.5 ± 5.8% for pure alginate to as low as 5.8 ± 1.2% for alginate/gelatin of 1:7 (w/w). It seems that gelatin successfully inhibited alginate chains mobility during their network re-arrangement by a Ca2+ cation. The FTIR spectra of hydrogels showed a combination of characteristic vibration of alginate and gelatin. Increasing gelatin content also significantly improved elasticity and tensile strength at break of dried hydrogels. Swelling kinetics of dried hydrogels were fitted with Schott’s second-order power-law model. Increasing gelatin fraction increased the swelling rate while decreased the swelling at equilibrium. Their absorptive capacity was of the interval for management of moderate to heavily exudating wound.
The Relationship between Elasticity of Polymeric Gels and the In vitro Releas...iosrjce
Gels are semi-solid dosage forms that comprise small amount of solids dispersed in relatively large
amount of liquid but still having solid-like structure. Rheological properties of gels may affect the release of
proposed medicaments from the polymeric gels. The objective of this research was to find the relationship
between the elasticity of polymeric gels and the in vitro release of Ketoconazole anti-fungal drug from different
types of gel structures. Five types of gel bases were prepared, glycerin of starch, gelatin-glycerin, sodium
carboxy methyl cellulose, Carbopol 934 and Eudragit L100. The rheological properties of gels were determined
using Rheometer. Whereas the in vitro release of ketoconazole from the mentioned gel bases were determined
using Franz Diffusion Cell. The results obtained showed that the higher the elasticity of the gel the more release of the drug.
Investigation on the printability of bioink based on alginate-gelatin hydroge...journalBEEI
Bioinks of 3D bioprinting have significant potential application in the field of tissue engineering to support cell attachment and proliferation. In this work, the alginate-gelatin-CELC (AGLC) bioink based on different compositions of alginate-gelatin (AG) hydrogel and cholesteryl ester liquid crystals (CELC) was prepared. Primarily, the alginate-gelatin hydrogel with certain concentration of gelatin (10-50%w/v) was investigated. The printability of the hydrogel reached a minimum width of 1.8 mm at a flow rate of 1 mL/min when the gelatin concentration was increased to 50% w/v (AG1050). Subsequently, the respective polymers with 10% w/v alginate and 50% w/v gelatin blended with 1%, 5%, 10%, 20%, 40%, and 60% w/v of CELC in the preparation of the alginate-gelatin-CELC bioink was further investigated.The printability of the bioink was examined by micro-extrusion based 3D bioprinter. The printability of the bioink enhanced by 27.8% as compared to AG1050 and reached a minimum width of 1.3 mm at a flow rate of 1 mL/min when the CELC concentration was increased to 40% and 60%. The tested properties of the bioink show that the CELC improve shear-thinning and lipid moieties properties to the composite bioink and hence, enhances its printability.
This study investigated using polyethylene glycol (PEG) as a cross-linking agent for protein extracts from rat dermal tissue to create a hydrogel with controllable properties for tissue engineering applications. Hydrogels with 1:1 ratios of PEGylated dermal extract and 2-5% PEGDA of molecular weights 3.4kDa and 20kDa were evaluated based on their ability to gel and swelling ratio. The results showed that 3% PEGDA with 3.4kDa molecular weight formed gels and had the highest swelling ratios, indicating it was the least cross-linked. The point of gel formation was determined to be 3% for 3.4kDa PEGDA and 4% for 20
This document summarizes research on immobilizing the enzyme laccase in an alginate-gelatin mixed gel and using it to decolorize synthetic dyes like crystal violet. Key findings include:
1) Spherical beads were formed using various alginate concentrations, with 5% alginate beads having the highest mechanical stability.
2) Both free and immobilized laccase worked best at pH 8-9 and 50°C for crystal violet decolorization.
3) The immobilized laccase retained 85% activity after 5 reuse cycles and effectively decolorized various dyes like amido black and malachite green.
This document provides an overview of pharmaceutical gels. It defines gels as semisolid systems where liquid movement is restricted by a 3D network. Gels are classified as single-phase or two-phase systems. Key properties include swelling, syneresis, aging, and thixotropy. Gels are used to deliver drugs orally, topically, and via injection. They are formulated by choosing appropriate vehicles, gelling agents, and additives. Gels are prepared via thermal, flocculation, or chemical methods. Evaluation parameters include homogeneity, pH, drug content, viscosity, spreadability, extrudability, skin irritation, and in vitro diffusion studies.
The effect of temperature onthe micellization of an anionic surfactant in mix...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.
Tissue engineering uses scaffolds, cells, and signaling molecules to regenerate tissues and organs. Scaffolds provide a structure for cell attachment, growth, and tissue formation. Natural polymers like collagen and hyaluronic acid, and synthetic polymers like poly-lactic-co-glycolic acid are commonly used as scaffold materials. Scaffolds can be fabricated using various methods including freeze drying, electrospinning, 3D printing, and textile technologies to produce scaffolds with desirable properties like porosity and pore size for tissue growth. Scaffolds seeded with stem cells or tissue-specific cells aim to repair and regenerate tissues for applications in skin, bone, cartilage, and other organs.
Expression Purification and Immunodetection of a fusion protein Glutathione S...iosrjce
Glutathione S Transferase(GST) is an enzyme of a multi gene family which is involved in reducing
oxidative damage to cells and detoxification of Xenobiotic compounds and plays critical role in life processes.
The entire work was completely qualitative and the objective of my work was to deal with the induction,
extraction and purification of the GST fusion protein from pGEX 3X vector.In order to achieve high degree of
transformed cells,the E.Coli BL21 host strain was made competent using 0.1M CaCl2 and adding of pGEX 3X
vector into host made it transformed.With the induction of GST protein by 0.1mM IPTG,the desired protein was
purified through glutathione Cl agarose column and was detected by immunoblotting method with the use of
anti GST HRP conjugate Ab which expressed the desired protein.
Expression Purification and Immunodetection of a fusion protein Glutathione S...iosrjce
IOSR Journal of Biotechnology and Biochemistry (IOSR-JBB) covers studies of the chemical processes in living organisms, structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules, chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions, genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction. IOSR-JBB is privileged to focus on a wide range of biotechnology as well as high quality articles on genetic engineering, cell and tissue culture technologies, genetics, microbiology, molecular biology, biochemistry, embryology, cell biology, chemical engineering, bioprocess engineering, information technology, biorobotics.
Buffers resist changes in pH and consist of a conjugate acid-base pair where the ratio of proton acceptor to proton donor is near unity. A webinar discusses how biological buffers can impact reproducibility and explores considerations for buffer selection and use to improve reproducibility. Key factors include how buffers may interact with metals and biological materials and tips for proper buffer selection and use. [END SUMMARY]
This document describes the development of composite polymer scaffolds made of PLGA/PEG particles combined with hydrogel components like Pluronic F127, fibrin, or hyaluronic acid. The scaffolds are formed by mixing the PLGA/PEG particles with a hydrogel at room temperature, then allowing them to solidify at 37°C as the particles sinter together over time. Testing showed the compressive strength of the scaffolds increased between 15 minutes and 2 hours at 37°C. The maximum strengths were 1.2 MPa for PLGA/PEG-Pluronic F127 scaffolds, 2.4 MPa for PLGA/PEG-hyaluronic acid scaffolds, and 0.6 MPa for PLGA
Properties of biopolymers produced by transglutaminase treatment of wpi and g...Eduard Hernàndez I PMP®
Byproduct utilization is an important consideration in the development of sustainable processes. Whey
protein isolate (WPI), a byproduct of the cheese industry, and gelatin, a byproduct of the leather industry,
were reacted individually and in blends with microbial transglutaminase (mTGase) at pH 7.5 and 45 C.
When a WPI (10% w/w) solution was treated with mTGase (10 U/g) under reducing conditions, the viscosity
increased four-fold and the storage modulus (G0) from 0 to 300 Pa over 20 h. Similar treatment
of dilute gelatin solutions (0.5–3%) had little effect. Addition of gelatin to 10% WPI caused a synergistic
increase in both viscosity and G0 , with the formation of gels at concentrations greater than 1.5% added
gelatin. These results suggest that new biopolymers, with improved functionality, could be developed
by mTGase treatment of protein blends containing small amounts of gelatin with the less expensive whey
protein.
PREPARATION AND ANALYSIS OF NOVEL HYDROGELS PREPARED FROM THE BLEND OF GUAR G...msejjournal
This research work deals with the preparation of a series of hydrogels using renewable resources, in order
to decrease the adverse impact on the environment, and understand their swelling behavior. Hydrogels
were synthesized using guar gum and chitosan with glutaraldehyde as the cross-linking agent, protonated
with 98% conc. sulphuric acid. Concentration of chitosan was varied as 0, 12.5, 25, 37.5 and 50% (w/w) in
guar gum, while that of glutaraldehyde was varied as 0, 1.5, 3 and 6% (w/w) of the total quantity of guar
gum and chitosan. Prepared hydrogels were characterized for moisture content, equilibrium water
absorbency, re-swelling capacity, swelling ability in acidic (pH = 3) and basic (pH = 11) pH distilled
water, equilibrium saline water absorbency and Fourier transform infrared spectroscopy. It was
determined that moisture content, equilibrium water absorbency and equilibrium saline water absorbency
decreased with increased concentration of chitosan and glutaraldehyde, but they still had water swelling to
be classified as hydrogel. Re-swelling capacity of the hydrogels decreased with increased cycles of reswelling. Prepared hydrogels maintained high water swelling in acidic pH distilled water as compared to
basic pH distilled water. This hydrogels can be utilized as eco-friendly water manageable materials.
Physicochemical Properties of Gelatin Extracted from Buffalo Hide Pretreated ...UniversitasGadjahMada
The acid pretreatment of collagen molecules disrupts their crosslinks and assists in the release of acid-soluble proteins, fats, and other components. Generally, to achieve optimum extraction efficiency, strong acids may be used at a lower acid concentration compared to weak acids. This study aimed to determine the yield and physicochemical properties of gelatins extracted from buffalo hides pretreated with different acids. Hides were extracted with hydrochloric, citric, and acetic acids at concentrations of 0.3, 0.6, 0.9, 1.2, and 1.5 M. A completely randomized design and the least significant difference test were used in the experimental design, and all measurements were performed in triplicate. The highest yield (29.17%) was obtained from pretreatment with 0.9 M HCl. The gel strength did not differ significantly (p>0.05) according to acid type (280.26-259.62 g Bloom), and the highest viscosity was obtained from the 0.6 M citric acid pretreatment. All the gelatins contained α- and β-chain components and several degraded peptides (24-66 kDa). The color and Fourier-transform infrared spectrum of the gelatin extracted using 0.9 M HCl were similar to those of commercial bovine skin gelatin. In general, the physicochemical properties of the gelatin complied with the industry standard set by the Gelatin Manufacturers Institute of America, revealing that buffalo hide could serve as a potential alternative source of gelatin.
This document provides an overview of pharmaceutical gels. It defines gels as semisolid colloidal systems where a liquid vehicle interacts with colloidal particles. The vehicle can be aqueous, hydroalcoholic, alcoholic, or non-aqueous. Gels are classified based on their continuous phase (organogels, hydrogels, xerogels) or the nature of bonds in their 3D network (dispersed solids, hydrophilic polymers). Common gelling agents include natural polymers, semisynthetic polymers, and synthetic polymers. The document discusses gel properties, preparation methods, manufacturing parameters, examples of topical gels, and applications of gels in drug delivery.
1. STONY BROOK UNIVERSITY
COLLEGE OF ENGINEERING AND APPLIED SCIENCES
Chemical and Molecular Engineering Program
Chemical Engineering Laboratory II:
CME 320
Hydrogels - Rheology
By
Marcin Kielkiewicz
Team Members: Jennifer Imbrogno & Kathryn Margaret Caducio
TA: Clement Marmorat
Submitted to:
Prof. Miriam Rafailovich and Dr. Pinkas-Sarafova
Submitted: April 15, 2015
2. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
Abstract
The properties of hydrogels, specifically pure gelatin and mTG cross-linked gelatin were compared to
determine the effect cross-linking has on rheological properties, thermal stability at body temperature,
solvent absorbance rate, and drug release. Two hydrogels, one with 10% weight by volume of gelatin in
deionized water was prepared with the other as 10% weight by volume mTG cross-linked hydrogel (with a
3:1 ration of mTG: gelatin). mTG catalyzes the formation of covalent bonds across gelatins molecular
structure, which are normally held together in gelatin by hydrogen bonds. This cross-linking strengthens
the hydrogel matrix as proven by the tests performed. Dynamic shear rheometry over a range of shear from
1-8000 Pa showed that the elastic modulus dominates over the range of shear for both gels, however it is
stronger in hardgel; this is attributed to cross-linking across gelatin macromolecules. The hardgel sample
was unexpectedly destroyed at a lower shear than pure gelatin, which can be attributed to a greater water
content between cross-linked gelatin molecules than within the molecular matrix as is the case for pure
gelatin. It was observed that dehydrated gelatin has a higher rate of water absorption than cross-linked
gelatin due to a decrease in pore size caused by cross-linking. Gels saturated with blue dye were also tested
for the release of dye at 37 °C in both dilute ethanol and deionized water. The hardgel remained in gel form
at elevated temperature, and more dye was released in deionized water than in dilute ethanol. From this we
can conclude that ethanol does not readily interchange with the solvent present within the hydrogel. Pure
gelatin samples “melted” at this temperature, and released all their dye in less than one hour. From these
results we canconclude that cross-linked gelatin has the potential to actasa biodegradable, extended release
drug delivery system.
Introduction
A hydrogel is a viscoelastic material
composed of a network of polymer chains that are
hydrophilic and highly absorbent; a typical
hydrogel can be composed of over 90% water by
weight. This property puts hydrogels in a unique
class of materials that have both sold solid
(elastic) and liquid (inelastic) properties.
Hydrogels are often homogenous materials
produced by either biological or synthetic
processes. Due to their substantial water content
hydrogels possess a degree of flexibility very
similar to vertebrate tissue. From a biomedical
perspective, they show promise in a number of
areas including drug delivery and regenerative
medicine. Hydrogels are already widely used as
three-dimensional scaffolds for cell and tissue
culture environments, as they are excellent
mimics of the in vivo state.1,2
One of the most common hydrogels of
biological origin is hydrated gelatin. Gelatin is
derived from collagen which is a highly abundant
structural protein found in various fibrous
tissues in vertebrates, including tendons,
ligaments, skin, blood vessels, corneas,cartilage,
etc. The collagen in each tissue is somewhat
unique in order to serve a specific biological
purpose in every species, and each type of
collagen varies across species as well. Therefore
it is impossible to assign a single structure to
collagen. However, all types of collagen are
composed of a triple helix, which generally
consists of two identical chains (α1) and an
additional chain that differs slightly in its
chemical composition (α2). The three primary
amino acids that compose all types of collagen
are glycine, proline, hydroxyproline, and alanine
which in sum account for over 50% of the total
amino acid content in the molecules. The
remainder is a combination of over a dozen amino
acids in varying concentrations.3-5
3. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
On an industrial scale, collagen is
harvested from animal tissue and hydrolyzed
under either acidic or basic conditions. This is
done in order to purify and decontaminate the raw
collagen. In this process collagen is broken down
into a simpler molecules of gelatin which share
all the properties of collagen, the only difference
being molecular weight.6,7
Because gelatin
is inexpensive and biodegradable its use for drug
delivery systems and tissue engineering has long
been sought after. A major challenge in utilizing
gelatin for this purpose has been its
decomposition at 35 °C,8
which is below human
body temperature, which lies at approximately
36.8° C ± 0.4 °C.9
The cause of decomposition is
the unwinding of the triple helix structure and
subsequent “melting”, which transforms the
hydrated gelatin from a hydrogel into a solution.
This renders gelatin a non-biocompatible
material when it is intended to remain in its gel
form for extended periods of time within the
human body. In order
to overcome this problem, we tested the effect of
cross-linking the triple helix structure of gelatin
with the microbial transglutaminase enzyme
(mTG). This enzyme catalyzes the formation
of isopeptide bonds between free amine groups
and the acyl group at the terminus of side chains
of protein or peptide bound glutamine. Bonds
formed by transglutaminase exhibit high
resistance to breakdown into smaller peptides and
amino acids.10
We predicted that by cross-linking
the triple helix structure the strands would be
unable to disassociate at body temperature and
remain stable at 37 °C for longer periods of time
compared to gelatin. Samples of pure
gelation and mTG cross-linked gelatin were
created and then compared through the following
tests. Their elastic modulus and viscous modulus
was measured over a range of shear using a
rheometer, Other samples were placed in an
incubator at 37 °C to observe whether they would
“melt”. The absorbent properties of both
dehydrated gels were measured, and the release
of blue dye (which simulated a drug) was
measured in both in pure water and dilute ethanol
to simulate the effects of drug release in an
inebriated patient versus a sober one. These tests
served as preliminary measurements to see
whethercross-linking affectsthe properties of the
hydrogel and whether it could serve as a
biomaterial for use within the human body.
Method and Materials
Our first hydrogels were created using
the following procedure: a 10% weight by
volume (w/v) sample of pure gelatin hydrogel
was prepared by adding 3.925 g of dehydrated
gelatin to 39.2 mL of deionized water at room
temperature in a plastic test tube. The mixture
wasthen heatedin an incubator at37 °Cto initiate
gel formation. This procedure was performed
because gelatin is relatively insoluble in cold
water but hydrates readily in warm water.11
By
cooling the solution below 37° C the triple helix
structure “recrystallized” and the hydrogel was
formed. A 10% w/v hard gel composed of a 3:1
mixture of gelatin: mTG was prepared via the
same procedure.
Two similarly sized samples of pure
gelatin and hard gel were subjected to a dynamic
shear rheometry test which measured the elastic
modulus and viscous modulus of each sample. A
dynamic shear rheometer is a device that is used
to measure the effects of shear on the hydrogels.
In the device a sample is placed between two
plates, and a minimum pressure is exerted onto
the sample to hold is stationary between the
plates. While one plate is held stationary the
second plate oscillates angularly relative to the
opposite plate. A predetermined range of torque
values are applied to the sample to determine its
rheological properties.12
Rheological properties
are often measured at a precise temperature
4. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
therefore external temperature control was
exercised. In our experimental setup a Bohlin
Gemini HR rheometer connected to an ETO
electronics heating unit was used. The
temperature was held constant at 25 °C for both
samples. A range of shearfrom 1 to 8000 Pa were
applied until the sample reached its critical shear
and wasdestroyed. Critical shearis defined asthe
shear required to cause atom planes to slip past
one another; in other words this is the point where
the viscous modulus exceeds the elastic modulus,
hence the sample becomes more liquid-like than
solid and is “liquidated” causing it to slip away
from between the plates.
The next test measured the rates of
absorbance of pure gelatin compared to hard gel
(3:1 mixture of gelatin: mTG). 10% w/v pure
gelatin hydrogel was placed in an incubator at 37
°C until the hydrogel “melted”. Using a
micropipette 3.000 mL of the warm gelatin
solution were added to a petri dish. This was
repeated two more times to give a total of three
samples of pure gelatin. Conversely, three
samples of hard gel were prepared by adding
2.250 mL of warm gelatin solution to each petri
dish. 0.750 mL of mTG was subsequently added
to each petri dish. Care was taken to avoid the
introduction of air bubbles into each petri dish.
Any bubbles that were substantial in size were
removed with the micropipette. The samples
were left to gel over several hours and then
dehydrated in air at room temperature for one
week. After one week the mass of each petri dish
was measured [iBalance 211TM
] and recorded.
Excess water was then added to each petri dish
and the gels were allowed to swell at room
temperature. After 67 minutes excess water was
drained and the mass of each petri dish was
recorded once more. The average mass of each
sample set was calculated using Eq. 1. The
population standard deviation of each sample set
was calculated suing Eq. 2.
[Equation 1] x̄ = N-1∑ 𝑥𝑁
𝑖=1 i
[Equation 2] σ = √∑ (𝑥𝑁
𝑖=1 i - x̄ ) ÷ N
From the information obtained from the
above test,the volume fraction of the solvent (ɸs,t)
within the hydrogel at a specific time t was
determined using Eq.3. This parameter is useful
for calculating the Gibbs free energy of mixing
according to the Flory-Huggins theory. In this
theory each polymer segment is described by a
position in a lattice which is as large as the
solvent molecules. Flory and Huggins gave an
expression for the enthalpy of mixing, which
would be zero for an ideal solution but is given
by Eq. 4. By using the Boltzmann relation for an
increase in entropy due to mixing in combination
with the probability function and Sterling
approximation an expression for the molar
entropy change of mixing is given by Eq. 5.14
From these two equations the Gibbs free energy
is easily calculated. This calculation was not
performed, however it has been included to show
the reader the significance of the volume fraction
parameter. The relative uncertainty in the volume
fraction is given by Eq. 6. Note that the
uncertainty in the density of water is negligible
and is omitted.
[Equation 3] ɸs,t =
𝑉𝑠
𝑉𝑝 + 𝑉𝑠
=
1
ρs
𝑄𝑚
𝜌𝑝
+
1
𝜌𝑠
Qm =
𝑚𝑎𝑠𝑠 (ℎ𝑦𝑑𝑟𝑎𝑡𝑒𝑑 𝑝𝑜𝑙𝑦𝑚𝑒𝑟)
𝑚𝑎𝑠𝑠 (𝑑𝑒ℎ𝑦𝑑𝑟𝑎𝑡𝑒𝑑 𝑝𝑜𝑙𝑦𝑚𝑒𝑟)
ρs = density (solvent)
ρP = density (polymer)
[Equation 4] ΔHm = zn1r1 ɸpΔw12
[Equation 5] ΔSm = -R∑ 𝑥𝑁
𝑖=1 iln[xi]
[Equation 6] δ% ɸs,t = ɸs,t*(δ%Qm + δ%ρP)
In a final test the theoretical release of a
drug from gelatin and hardgel was observed in
both deionized water and an ethanol/water
5. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
solution. Pure gelation and hard gel were both
saturated with water containing a blue dye for an
extended period of time prior to initiating this
6. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
solution. Pure gelation and hard gel were both
saturated with water containing a blue dye for an
extended period of time prior to initiating this
7. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
solution. Pure gelatin and hard gel were both
saturated with water containg blue dye prior to
initiating this experiment. The blue dye was
intended to simulate a theoretical drug. The
ethanol solution was meant to emulate the
bloodstream conditions of a highly inebriated
patient while the pure water emulated those of a
sober patient. Four equal volume samples of
gelatin and hard gel were prepared (two each),
and one of eachgelwasplaced in either a testtube
with deionized water or one with a 35% ethanol
by volume solution. 3.000 mL of deionized
water was added to two test tubes, while 1.500
mL of 70% ethanol in water was added to two
other test tubes and diluted with an additional
1.500 mL. All solutions were made using a
micropipette. The four test tubes were sealed in
an incubator at 37 °C and wrapped with
aluminum foil (to prevent light from interacting
with the samples) and kept there for 47 minutes.
The extent of release of blue eye was estimated
by eye and the samples were visually compared
relative to one another.
.
Results and Discussion
The results of the rheometry test for both the pure
gelatin hydrogel and the hardgel are shown in Fig.
1 and Fig. 2, respectively. From the data obtained
it is clear that the elastic modulus (G’) is
dominant and linear in both samples over a range
of shear from 1-1000 Pa. G’ is greater for the
hardgel than for pure gelatin in this range. This
result can be explained by the cross-linking in the
hardgel, which in theory could occur within the
triple helix structure of gelatin as well as across
individual triple helix strands. The cross-linking
across strands increases the internal organization
within the polymer matrix and in turn increases
the ability of the hydrogel to resist shear stress.
Beyond 1000 Pa of shear stress the viscous
modulus in both samples began increasing
exponentially while the elastic modulus begins
decreasing. The rate of change in both samples
differed significantly, with a decomposition of
the hard gel occurring at a critical shear of
approximately 5500 Pa. The critical shear for
pure gelatin was extrapolated to a value of
roughly 13500 Pa, more than twice as large as
that of the hardgel. This result was unexpected,
but it can also be explained by the cross-linking
within the hardgel. The cross-linking in the
hardgel reduces the pore sizes within the polymer
matrix, hence there could be more water residing
outside of the polymer structure than within it
when compared to pure gelatin, which has larger
pores. Since more water rests outside of the
polymer matrix individual planes of gel can begin
to slide past one another at a lower shear,because
the planes are largely composed of water and are
therefore more “liquid-like” in nature than of
those found in gelatin.
8. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
Figure 2. Results obtained for the
rheometry test for the hardgel.
For the absorption test, the mass of the
dehydrated hardgel and gelatin, their hydrated
counterparts, and related calculations are shown
in Table 1. The standard mass of a 60 mm * 15
mm petri dish was 2.268 g, which was used to
calculate the mass of hydrogel in each dish. The
uncertainty of 0.001 g in the electronic scale was
omitted in favor of calculating a standard
deviation and using one standard deviation as the
error in the mean mass of gelatin in each petri
dish. It wasfound that dehydration of both gelatin
and hardgel samples resulted in a loss of nearly
equal volumes of water; the average mass of pure
gelatin in eachpetridish was0.666 g ± 11.7% and
for the hardgel it was 0.617 ± 7.9%. The mass of
hardgel wasexpectedto be smaller because 0.750
mL less of gelatin solution was used to make it
when compared to pure gelatin. Although the
initial masses were similar, the rates of
absorbance differed significantly between the
two gels. Pure gelatin was able to absorb two
equivalents of its mass in water weight to yield a
hydrogel with a mass of 1.768 g ± 6.9%. The
hardgel absorbed only one equivalent of its
weight in water with a final mass of 1.294 g ±
4.2%. The different rates of absorbance can be
explained by cross-linking/lack of cross-linking;
the hardgel has smaller pores and does not absorb
water as quickly as gelatin which has larger pores
and swells at a faster rate.
Using Eq. 3, Eq. 6, and the data from
Table 1, the value of δ% ɸgelatin,67 min was found to
be 0.782 ± 22.3% while the value of δ% ɸhardgel,67
min was0.739 ± 15.8%. Since anunknown amount
of moisture was present in the air, the samples
could not have been completely devoid of water.
Figure 1. Results
obtained for the
rheometry test of
pure gelatin hydrogel.
9. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
Assuming the samples retained 8% to 13% of
their initial water concentration, which is a
common value for air dried samples, the density
of gelatin at that level of water content is (1.35 ±
0.05) g/cm3
.13
The density of water at 25 °C is
known with high precision to be 0.997 g/cm3
therefore the uncertainty in it is negligible.14
In a final test the release of blue dye from
gelatin and hardgel was observed in both
deionized water and an ethanol/water solution.
After 47 min in the incubator, both gelatin
samples dissolved in ethanol and pure water,
releasing all of their blue dye. The hardgel
samples did not dissolve in either solution,
however it appeared that the sample placed in
water released more dye than the one in ethanol.
This seems to indicate that ethanol cannot readily
passthrough the pores within the polymer matrix,
and as the pores get smaller the rate of solvent
interchange decreases. This test also proved that
mTG cross-linked gelatin is stable at 37 °C in
both water and ethanol.
TABLE 1
Sample # Pure Gelatin
(dehydrated) w/
Petri Dish
Pure Gelatin
(hydrated) w/
Petri Dish
Hardgel
(dehydrated) w/
Petri dish
Hardgel
(hydrated) w/
Petri dish
1 2.831 g 3.867 g 2.950 g 3.638 g
2 3.021 g 4.141 g 2.875 g 3.527 g
3 2.950 g 4.099 g 2.831 g 3.521 g
Pure Gelatin
(dehydrated)
w/out Petri Dish
Pure Gelatin
(hydrated)
w/outPetri Dish
Hardgel
(dehydrated)
w/out Petri dish
Hardgel
(hydrated)
w/out Petri dish
1 0.563 g 1.599 g 0.682 g 1.370 g
2 0.753 g 1.873 g 0.607 g 1.259 g
3 0.682 g 1.831 g 0.563 g 1.253 g
Pure Gelatin
(dehydrated)
Average Mass
Pure Gelatin
(hydrated)
Average Mass
Hardgel
(dehydrated)
Average Mass
Hardgel
(hydrated)
Average Mass
0.666 g 1.768 g 0.617 g 1.294 g
Pure Gelatin
(dehydrated)
Std. Deviation
Pure Gelatin
(hydrated)
Std. Deviation
Hardgel
(dehydrated)
Std. Deviation
Hardgel
(hydrated) Std.
Deviation
10. Marcin Kielkiewicz 108225444 CME 320 Hydrogels April 15, 2015
0.078 g 0.120 g 0.049 g 0.054 g
Conclusion
The properties of mTG cross-linked gelatin and
pure gelatin were compared using several tests.
mTG cross-linked gelatin had a higher elastic
modulus than pure gelatin, but the cross-linked
sample could not withstand shear as well as
gelatin. The absorbance rate test showed that
cross-linking decreases the pore size within the
polymer matrix hence limiting the rate of solvent
absorption. Cross-linked gelatin was only able to
absorb
2
3
of the waterabsorbedby pure gelatin. As
a drug delivery system, cross-linked gelatin
showed promise because it didn’t decompose at
body temperature yet managed to release blue
dye in both wateranddilute ethanol, albeit slower
in the latter. Pure gelatin, on the other hand,
decomposed quickly at body temperature
releasing all the dye in less than one hour,
limiting its potential effectiveness as an extended
release drug delivery method.
References
1) Elisseeff, Jennifer. "Hydrogels: Structure Starts to
Gel." Nature Materials. 7.4 (2008): 271-73.
2) J.M. Van Bemmel. “Der Hydrogel und das
kristallinische Hydrat des Kupferoxydes.” Z. Anorg.
Chem. 5 (1894) S. 466.
3) Lullo, G. A. Di. "Mapping the Ligand-binding Sites
and Disease-associated Mutations on the Most
Abundant Protein in the Human, Type I Collagen.
“Journal of Biological Chemistry. 277.6 (2001):
4223-231.
4) Sikorski, Zdzisław E. Chemical & Functional
Properties of Food Proteins. Lancaster, PA:
Technomic, 2001.
5) Szpak, Paul. "Fish Bone Chemistry and
Ultrastructure: Implications for Taphonomy and
Stable Isotope Analysis." Journal of Archaeological
Science. 38.12 (2011): 3358-372.
6) "Gelatin." Food Chemistry 45300. PDF. Purdue
University.
7) Ward, A. G., and A. Courts. The Science and
Technology of Gelatin. London: Academic, 1977.
8) Cole, CGB (2000), "Gelatin", in Francis,
FJ, Encyclopedia of Food Science and Technology,
2nd edition, John Wiley & Sons, pp. 1183–1188.
9) Longo, Dan L. Harrison's Principles of Internal
Medicine. New York, N.Y.: McGraw-Hill, 2012.
10) Clarke, D.d., M.j. Mycek, A. Neidle, and H.
Waelsch. "The Incorporation of Amines into
Protein." Archives of Biochemistry and Biophysics. 79
(1959): 338-54.
11) "Solubility." PB Gelatins. Tessenderlo Group.
Web. 13 Apr. 2015.
13) Members, GMIA. "Gelatin Handbook." Gelatin
Manufacturers Institute of America. Web. 15 Apr.
2015.
14) "Water Density Calculator." Web. 15 Apr. 2015.