This document describes an approach to modulating protein release from large poly(DL-lactic acid-co-glycolic acid) (PLGA) microparticles for tissue engineering applications. Two PLGA-PEG-PLGA triblock copolymers were synthesized and blended with PLGA 85:15 polymer to form microparticles loaded with lysozyme as a model protein. The glass transition temperature and protein release profiles of microparticles containing 10% or 30% triblock copolymer by weight were analyzed and compared to microparticles containing only PLGA 85:15 polymer. Blending triblock copolymers was found to increase the total lysozyme release and shorten the release period from the microparticles.
Combined effects of PEGylation and particle size on uptake of PLGA particles ...Nanomedicine Journal (NMJ)
Abstract
Objective:
At the present study, relationship between phagocytosis of PLGA particles and combined effects of particle size and surface PEGylation was investigated.
Materials and Methods:
Microspheres and nanospheres (3500 nm and 700 nm) were prepared from three types of PLGA polymers (non-PEGylated and PEGylation percents of 9% and 15%). These particles were prepared by solvent evaporation method. All particles were labeled with FITC-Albumin. Interaction of particles with J744.A.1 mouse macrophage cells, was evaluated in the absence or presence of 7% of the serum by flowcytometry method.
Results:
The study revealed more phagocytosis of nanospheres. In the presence of the serum, PEGylated particles were phagocytosed less than non-PEGylated particles. For nanospheres, this difference was significant (P<0/05) and their uptake was affected by PEGylation degree. In the case of microsphere formulation, PEGylation did not affect the cell uptake. In the serum-free medium, the bigger particles had more cell uptake rate than smaller ones but the cell uptake rate was not influenced by PEGylation.
Conclusion:
The results indicated that in nanosized particles both size and PEgylation degree could affect the phagocytosis, but in micron sized particles just size, and not the PEGylation degree, could affect this.
Preparation of protein-loaded PLGA-PVP blend nanoparticles by nanoprecipitati...Nanomedicine Journal (NMJ)
Abstract
Objective(s):
Despite of wide range applications of polymeric nanoparticles in protein delivery, there are some problems for the field of protein entrapment, initial burst and controlled release profile.
Materials and Methods:
In this study, we investigated the influence of some changes in PLGA nanoparticles formulation to improve the initial and controlled release profile. Selected parameters were: pluronic F127, polysorbate 80 as surfactant, pH of inner aqueous phase, L/G ratio of PLGA polymer, volume of inner aqueous phase and addition of polyvinylpyrrolidone as an excipient. FITC-HSA was used as a model hydrophilic drug. The nanoparticles were prepared by nanoprecipitation.
Results:
Initial release of FITC-HSA from PLGA-tween 80 nanoparticles (opt-4, 61%) was faster than control (PLGA-pluronic) after 2.30 h of incubation. Results showed that decrease in pH of inner aqueous phase to pI of protein can decrease IBR but the release profile of protein is the same as control. Release profile with three phases including a) initial burst b) plateau and c) final release phase was observed when we changed volume of inner aqueous phase and L/G ratio in formulation. Co-entrapment of HSA with PVP and pluronic reduced the IBR and controlled release profile in opt-19. Encapsulation efficiency was more than 97% and nanoparticles size and zeta potentials were mono-modal and -18.99 mV, respectively.
Conclusion:
In this research, we optimized a process for preparation of PLGA-PVP-pluronic nanoparticles of diameter less than 300 nm using nanoprecipitation method. This formulation showed a decreased initial burst and long lasting controlled release profile for FITC-HSA as a model drug for proteins.
1) Nucleotides and phosphorylation can both positively and negatively modulate the binding of CaMKII to the NMDA receptor subunit GluN2B.
2) Adding ATP to in vitro experiments enhanced CaMKII binding to GluN2B, through two positive effects (direct nucleotide binding and CaMKII autophosphorylation) and two negative effects (GluN2B phosphorylation and additional CaMKII autophosphorylation).
3) Within cells, where ATP levels are high, nucleotide binding was required for efficient CaMKII interaction with GluN2B, whereas CaMKII autophosphorylation was not, suggesting nucleotide binding acts faster than the inhibitory phosphorylation reactions.
Piroxicam Nanostructured Lipid Carrier Drug Delivery SystemYogeshIJTSRD
This document describes a study that developed and evaluated a piroxicam (PXM) nanostructured lipid carrier (NLC) gel for topical delivery. PXM-loaded NLCs were prepared using the high-pressure homogenization method and characterized for particle size, drug entrapment efficiency, and in vitro drug release. The optimized NLC formulation was incorporated into a gel and evaluated for properties such as viscosity, drug content, and in vitro diffusion. Ex vivo skin irritation studies showed the gel caused no irritation. In vivo tests in rats demonstrated the NLC gel effectively reduced carrageenan-induced paw edema, indicating anti-inflammatory effects. Overall, the NLC gel was found to be a promising delivery
Long acting injectable microparticle formulation - a new dimension for peptid...Merck Life Sciences
Explore the clinical benefits and applications of sustained release drug delivery with this presentation. Access the findings from a technical feasibility study as well as a case study on sustained release microparticle formulation for a sensitive peptide.
Collagen hybridizing peptides (CHPs) can preferentially target denatured collagen strands and have applications in diagnostics, drug delivery, and regenerative medicine. While triple helical CHPs have high serum stability, monomeric CHPs that can bind denatured collagen have yet to be tested for serum stability. This study finds that monomeric CHPs containing the (GPO)n collagen motif are resistant to endopeptidase activity but subject to exopeptidase degradation. N-terminal modification of monomeric CHPs suppresses this degradation, resulting in high serum stability comparable to triple helical CHPs. An IR680-labeled CHP conjugate used for in vivo imaging showed similar tissue binding patterns
This document summarizes a study that characterized the heme binding properties of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The key findings include:
1) GAPDH binds heme substoichiometrically, with one heme binding per GAPDH tetramer. The heme forms low-spin complexes with GAPDH that have distinct UV-visible absorption spectra depending on the heme redox state.
2) Kinetic analysis found heme binding to GAPDH is reversible and selective for heme structure. Heme binding affinity ranges from 19-390 nM depending on redox conditions.
3) Spectroscopic analysis indicates the heme in the GAPDH complex is bis-ligated by a histidine residue as the proximal
Robert Graff's research focuses on the synthesis, characterization, and applications of branched polymers. He has developed two strategies for producing nanostructured branched polymers with highly controlled structures using confined spaces and living chain growth mechanisms. This allows precise control over molecular weight, structure, and properties. The polymers have applications in catalysis, drug delivery, and more due to their globular structure and functional group concentration. Graff has published extensively on the synthesis techniques and characterization methods, and on exploring the polymers' properties and applications through collaborations.
Combined effects of PEGylation and particle size on uptake of PLGA particles ...Nanomedicine Journal (NMJ)
Abstract
Objective:
At the present study, relationship between phagocytosis of PLGA particles and combined effects of particle size and surface PEGylation was investigated.
Materials and Methods:
Microspheres and nanospheres (3500 nm and 700 nm) were prepared from three types of PLGA polymers (non-PEGylated and PEGylation percents of 9% and 15%). These particles were prepared by solvent evaporation method. All particles were labeled with FITC-Albumin. Interaction of particles with J744.A.1 mouse macrophage cells, was evaluated in the absence or presence of 7% of the serum by flowcytometry method.
Results:
The study revealed more phagocytosis of nanospheres. In the presence of the serum, PEGylated particles were phagocytosed less than non-PEGylated particles. For nanospheres, this difference was significant (P<0/05) and their uptake was affected by PEGylation degree. In the case of microsphere formulation, PEGylation did not affect the cell uptake. In the serum-free medium, the bigger particles had more cell uptake rate than smaller ones but the cell uptake rate was not influenced by PEGylation.
Conclusion:
The results indicated that in nanosized particles both size and PEgylation degree could affect the phagocytosis, but in micron sized particles just size, and not the PEGylation degree, could affect this.
Preparation of protein-loaded PLGA-PVP blend nanoparticles by nanoprecipitati...Nanomedicine Journal (NMJ)
Abstract
Objective(s):
Despite of wide range applications of polymeric nanoparticles in protein delivery, there are some problems for the field of protein entrapment, initial burst and controlled release profile.
Materials and Methods:
In this study, we investigated the influence of some changes in PLGA nanoparticles formulation to improve the initial and controlled release profile. Selected parameters were: pluronic F127, polysorbate 80 as surfactant, pH of inner aqueous phase, L/G ratio of PLGA polymer, volume of inner aqueous phase and addition of polyvinylpyrrolidone as an excipient. FITC-HSA was used as a model hydrophilic drug. The nanoparticles were prepared by nanoprecipitation.
Results:
Initial release of FITC-HSA from PLGA-tween 80 nanoparticles (opt-4, 61%) was faster than control (PLGA-pluronic) after 2.30 h of incubation. Results showed that decrease in pH of inner aqueous phase to pI of protein can decrease IBR but the release profile of protein is the same as control. Release profile with three phases including a) initial burst b) plateau and c) final release phase was observed when we changed volume of inner aqueous phase and L/G ratio in formulation. Co-entrapment of HSA with PVP and pluronic reduced the IBR and controlled release profile in opt-19. Encapsulation efficiency was more than 97% and nanoparticles size and zeta potentials were mono-modal and -18.99 mV, respectively.
Conclusion:
In this research, we optimized a process for preparation of PLGA-PVP-pluronic nanoparticles of diameter less than 300 nm using nanoprecipitation method. This formulation showed a decreased initial burst and long lasting controlled release profile for FITC-HSA as a model drug for proteins.
1) Nucleotides and phosphorylation can both positively and negatively modulate the binding of CaMKII to the NMDA receptor subunit GluN2B.
2) Adding ATP to in vitro experiments enhanced CaMKII binding to GluN2B, through two positive effects (direct nucleotide binding and CaMKII autophosphorylation) and two negative effects (GluN2B phosphorylation and additional CaMKII autophosphorylation).
3) Within cells, where ATP levels are high, nucleotide binding was required for efficient CaMKII interaction with GluN2B, whereas CaMKII autophosphorylation was not, suggesting nucleotide binding acts faster than the inhibitory phosphorylation reactions.
Piroxicam Nanostructured Lipid Carrier Drug Delivery SystemYogeshIJTSRD
This document describes a study that developed and evaluated a piroxicam (PXM) nanostructured lipid carrier (NLC) gel for topical delivery. PXM-loaded NLCs were prepared using the high-pressure homogenization method and characterized for particle size, drug entrapment efficiency, and in vitro drug release. The optimized NLC formulation was incorporated into a gel and evaluated for properties such as viscosity, drug content, and in vitro diffusion. Ex vivo skin irritation studies showed the gel caused no irritation. In vivo tests in rats demonstrated the NLC gel effectively reduced carrageenan-induced paw edema, indicating anti-inflammatory effects. Overall, the NLC gel was found to be a promising delivery
Long acting injectable microparticle formulation - a new dimension for peptid...Merck Life Sciences
Explore the clinical benefits and applications of sustained release drug delivery with this presentation. Access the findings from a technical feasibility study as well as a case study on sustained release microparticle formulation for a sensitive peptide.
Collagen hybridizing peptides (CHPs) can preferentially target denatured collagen strands and have applications in diagnostics, drug delivery, and regenerative medicine. While triple helical CHPs have high serum stability, monomeric CHPs that can bind denatured collagen have yet to be tested for serum stability. This study finds that monomeric CHPs containing the (GPO)n collagen motif are resistant to endopeptidase activity but subject to exopeptidase degradation. N-terminal modification of monomeric CHPs suppresses this degradation, resulting in high serum stability comparable to triple helical CHPs. An IR680-labeled CHP conjugate used for in vivo imaging showed similar tissue binding patterns
This document summarizes a study that characterized the heme binding properties of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The key findings include:
1) GAPDH binds heme substoichiometrically, with one heme binding per GAPDH tetramer. The heme forms low-spin complexes with GAPDH that have distinct UV-visible absorption spectra depending on the heme redox state.
2) Kinetic analysis found heme binding to GAPDH is reversible and selective for heme structure. Heme binding affinity ranges from 19-390 nM depending on redox conditions.
3) Spectroscopic analysis indicates the heme in the GAPDH complex is bis-ligated by a histidine residue as the proximal
Robert Graff's research focuses on the synthesis, characterization, and applications of branched polymers. He has developed two strategies for producing nanostructured branched polymers with highly controlled structures using confined spaces and living chain growth mechanisms. This allows precise control over molecular weight, structure, and properties. The polymers have applications in catalysis, drug delivery, and more due to their globular structure and functional group concentration. Graff has published extensively on the synthesis techniques and characterization methods, and on exploring the polymers' properties and applications through collaborations.
This very short document contains a single word "Presentation" followed by an emoticon and text expression celebrating and concluding a presentation. It briefly acknowledges the end of a presentation with positive sentiment in a concise and informal manner.
Supermercados Peruanos S.A. es la segunda cadena de supermercados más grande en Perú, con 106 tiendas en todo el país. El documento analiza el desempeño financiero de Supermercados Peruanos en 2015, resaltando un aumento del 5.79% en las ventas netas con respecto a 2014, llegando a S/ 4,076.98 millones. Además, la empresa ha logrado mantener ratios positivos de rentabilidad y eficiencia gracias a su proceso de expansión y mayor posicionamiento en el mercado, respaldados por su accionista mayor
El documento describe la importancia de tener una presencia en Internet coherente con la estrategia de la empresa. Explica que la presencia en la red debe cubrir las necesidades de información de los públicos objetivo y posicionar la marca según la estrategia definida. Además, destaca la necesidad de optimizar el acceso a la información de manera eficiente a través de todos los canales disponibles.
Profiling systems have achieved notable adoption by research institutions.1 Multi-site search of research profiling systems has substantially evolved since the first deployment of systems such as DIRECT2Experts.2 CTSAsearch is a federated search engine using VIVO-compliant Linked Open Data (LOD) published by members of the NIH-funded Clinical and Translational Science (CTSA) consortium and other interested parties. Sixty-four institutions are currently included, spanning six distinct platforms and three continents (North America, Europe and Australia). In aggregate, CTSAsearch has data on 150-300 thousand unique researchers and their 10 million publications. The public interface is available at http://research.icts.uiowa.edu/polyglot.
Electronic dress for navigation of visually challenged personSophia
This document describes an electronic navigation system designed to help visually impaired individuals navigate indoor environments independently. The system uses RF transmitters and receivers to determine the user's location and provide voice directions to their destination. An infrared sensor is also used to detect obstacles and warn the user. When developed, it will allow blind individuals to travel without needing assistance or a walking stick by sensing their surroundings and providing turn-by-turn navigation instructions through an audio interface.
This document describes the development of a novel growth factor delivery system using poly(lactic-co-glycolic acid) (PLGA) microparticles. The inclusion of a hydrophilic PLGA-PEG-PLGA triblock copolymer alters the release kinetics from the microparticles such that growth factor release can occur before polymer degradation. Three formulations are identified as promising candidates for delivering growth factors like BMP-2, with adjustable release profiles from 4 days to over 4 weeks. Mixing microparticles of different formulations provides another method to control release kinetics. This customized, localized delivery system has the potential to improve the efficacy and safety of recombinant growth factor therapies.
P
a
N
A
D
a
A
R
R
A
A
K
C
L
B
N
1
r
C
1
C
m
s
[
i
p
a
r
i
0
h
Colloids and Surfaces B: Biointerfaces 101 (2013) 353– 360
Contents lists available at SciVerse ScienceDirect
Colloids and Surfaces B: Biointerfaces
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c o l s u r f b
harmacokinetics of curcumin-loaded PLGA and PLGA–PEG blend nanoparticles
fter oral administration in rats
ajeh Maissar Khalil , Thuane Castro Frabel do Nascimento , Diani Meza Casa , Luciana Facco Dalmolin ,
na Cristina de Mattos, Ivonete Hoss, Marco Aurélio Romano, Rubiana Mara Mainardes ∗
epartment of Pharmacy, Universidade Estadual do Centro-Oeste/UNICENTRO, Rua Simeão Camargo Varela de Sá 03, 85040-080 Guarapuava, PR, Brazil
r t i c l e i n f o
rticle history:
eceived 2 March 2012
eceived in revised form 10 June 2012
ccepted 12 June 2012
vailable online 28 June 2012
eywords:
urcumin
C–MS/MS
ioavailability
anoparticles
a b s t r a c t
The aim of this study was to assess the potential of nanoparticles to improve the pharmacokinetics of
curcumin, with a primary goal of enhancing its bioavailability. Polylactic-co-glycolic acid (PLGA) and
PLGA–polyethylene glycol (PEG) (PLGA–PEG) blend nanoparticles containing curcumin were obtained
by a single-emulsion solvent-evaporation technique, resulting in particles size smaller than 200 nm. The
encapsulation efficiency was over 70% for both formulations. The in vitro release study showed that cur-
cumin was released more slowly from the PLGA nanoparticles than from the PLGA–PEG nanoparticles. A
LC–MS/MS method was developed and validated to quantify curcumin in rat plasma. The nanoparticles
were orally administered at a single dose in rats, and the pharmacokinetic parameters were evaluated
and compared with the curcumin aqueous suspension. It was observed that both nanoparticles formu-
lations were able to sustain the curcumin delivery over time, but greater efficiency was obtained with
the PLGA–PEG nanoparticles, which showed better results in all of the pharmacokinetic parameters ana-
lyzed. The PLGA and PLGA–PEG nanoparticles increased the curcumin mean half-life in approximately 4
and 6 h, respectively, and the Cmax of curcumin increased 2.9- and 7.4-fold, respectively. The distribution
and metabolism of curcumin decreased when it was carried by nanoparticles, particularly PLGA–PEG
nanoparticles. The bioavailability of curcumin-loaded PLGA–PEG nanoparticles was 3.5-fold greater than
the curcumin from PLGA nanoparticles. Compared to the curcumin aqueous suspension, the PLGA and
PLGA–PEG nanoparticles increased the curcumin bioavailability by 15.6- and 55.4-fold, respectively.
These results suggest that PLGA and, in particular, P.
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
This document summarizes a study that explored using an aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and sodium citrate to purify lectin from Canavalia grandiflora seeds. A 24 full factorial design was used to study how four factors (PEG molar mass, PEG concentration, pH, and citrate concentration) affected the partitioning of the lectin ConGF. The results showed that ConGF preferentially partitioned to the PEG-rich top phase. A system of 20% PEG 400 and 20% citrate at pH 6 allowed recovery of ConGF with an 8.67 partitioning coefficient and 104% yield, demonstrating the efficiency of this ATPS for pur
Intranasal delivery of drug loaded thiolated co-polymeric microparticles for...Gaurav Patil
E-Presentation at Two days 15th Indo-US virtual International Conference
on “Global advances in Pharmaceutical and Allied Science”
In collaboration with
APP Gujarat State branch, AAP American International branch,
AAP Pharmedu Healthcare Manag Division
This document describes a study that evaluated the use of anion exchange chromatography to purify polyclonal immunoglobulin G (IgG) antibodies from rabbit serum. Two anion exchangers - DEAE and Q XL - were tested for their ability to remove albumin from rabbit serum while retaining IgG. The optimal conditions for albumin removal using DEAE were a pH of 8.0 and initial protein concentration of 0.5 mg/ml. Under these conditions, DEAE removed over 90% of albumin with less than 20% IgG loss, yielding 80% of IgG at 83% purity. Q XL also removed 90% of albumin but yielded only 70% of IgG at 62% purity. Therefore, DEAE
The document discusses poly(lactic-co-glycolic acid) (PLGA), a biodegradable polymer. It provides details on the synthesis of PLGA from lactide and glycolide monomers, its properties such as solubility and glass transition temperature, and its biodegradation process. Applications of PLGA include drug delivery systems, medical implants, and tissue engineering scaffolds. Case studies show that modifying PLGA with other polymers or peptides can improve drug permeability and distribution in tissues.
New tools bring greater understanding to cellular metabolism research Mourad FERHAT, PhD
Presentation of Promega Solutions in the field of cellular Metabolism research. Discover new bioluminescent assays for the detection of several metabolites and metabolic process such as : Glucose Uptake, Glucose consumption, Lactate secretion and Glutamine/Glutamate metabolism.
1. The document analyzes the degradation of PLGA and PGA-co-PDL polymeric nanoparticles (NPs) in simulated lung fluid (SLF) for pulmonary drug delivery applications.
2. Results showed PLGA NPs reduced in size over time, indicating degradation, while PGA-co-PDL NPs aggregated and increased in size.
3. PLGA NPs produced a more acidic environment as they degraded, which could potentially cause more inflammation than PGA-co-PDL NPs in vivo.
Formulation and characterization of epigallocatechin gallate nanoparticlesRamkumar Ponnuraj
This document describes the formulation and characterization of Epigallocatechin gallate (EGCG) nanoparticles. EGCG was encapsulated in chitosan nanoparticles using ionic gelation with sodium tripolyphosphate to improve its bioavailability. Different ratios of EGCG to chitosan were tested, and a 1:0.5 ratio showed the highest drug loading and encapsulation efficiency. The resulting nanoparticles were spherical with a size range of 198-385 nm. In vitro drug release and characterization studies demonstrated the nanoparticles were a promising delivery system for EGCG with improved absorption.
1) The document describes a study that encapsulated the growth factor BMP-2 within PLGA/PLGA-PEG-PLGA microparticles to develop a delivery system for sustained release of BMP-2.
2) Characterization showed the microparticles were spherical with a mean diameter of 98 μm and encapsulation efficiency of 57%. In vitro release studies demonstrated sustained release of BMP-2 from the microparticles over 2 weeks without an initial burst release.
3) Cell culture experiments showed the released BMP-2 was bioactive and promoted greater osteogenic differentiation of MC3T3-E1 cells than osteogenic supplements, as demonstrated by increased alkaline phosphatase activity and mineralization.
PROTAC Delivery System Recent Research Advances.pdfDoriaFang
The combination of PROTAC and multifunctional delivery systems will open up new research directions in the field of TPD. Here we will introduce the combination of PROTAC and multifunctional delivery systems.
This very short document contains a single word "Presentation" followed by an emoticon and text expression celebrating and concluding a presentation. It briefly acknowledges the end of a presentation with positive sentiment in a concise and informal manner.
Supermercados Peruanos S.A. es la segunda cadena de supermercados más grande en Perú, con 106 tiendas en todo el país. El documento analiza el desempeño financiero de Supermercados Peruanos en 2015, resaltando un aumento del 5.79% en las ventas netas con respecto a 2014, llegando a S/ 4,076.98 millones. Además, la empresa ha logrado mantener ratios positivos de rentabilidad y eficiencia gracias a su proceso de expansión y mayor posicionamiento en el mercado, respaldados por su accionista mayor
El documento describe la importancia de tener una presencia en Internet coherente con la estrategia de la empresa. Explica que la presencia en la red debe cubrir las necesidades de información de los públicos objetivo y posicionar la marca según la estrategia definida. Además, destaca la necesidad de optimizar el acceso a la información de manera eficiente a través de todos los canales disponibles.
Profiling systems have achieved notable adoption by research institutions.1 Multi-site search of research profiling systems has substantially evolved since the first deployment of systems such as DIRECT2Experts.2 CTSAsearch is a federated search engine using VIVO-compliant Linked Open Data (LOD) published by members of the NIH-funded Clinical and Translational Science (CTSA) consortium and other interested parties. Sixty-four institutions are currently included, spanning six distinct platforms and three continents (North America, Europe and Australia). In aggregate, CTSAsearch has data on 150-300 thousand unique researchers and their 10 million publications. The public interface is available at http://research.icts.uiowa.edu/polyglot.
Electronic dress for navigation of visually challenged personSophia
This document describes an electronic navigation system designed to help visually impaired individuals navigate indoor environments independently. The system uses RF transmitters and receivers to determine the user's location and provide voice directions to their destination. An infrared sensor is also used to detect obstacles and warn the user. When developed, it will allow blind individuals to travel without needing assistance or a walking stick by sensing their surroundings and providing turn-by-turn navigation instructions through an audio interface.
This document describes the development of a novel growth factor delivery system using poly(lactic-co-glycolic acid) (PLGA) microparticles. The inclusion of a hydrophilic PLGA-PEG-PLGA triblock copolymer alters the release kinetics from the microparticles such that growth factor release can occur before polymer degradation. Three formulations are identified as promising candidates for delivering growth factors like BMP-2, with adjustable release profiles from 4 days to over 4 weeks. Mixing microparticles of different formulations provides another method to control release kinetics. This customized, localized delivery system has the potential to improve the efficacy and safety of recombinant growth factor therapies.
P
a
N
A
D
a
A
R
R
A
A
K
C
L
B
N
1
r
C
1
C
m
s
[
i
p
a
r
i
0
h
Colloids and Surfaces B: Biointerfaces 101 (2013) 353– 360
Contents lists available at SciVerse ScienceDirect
Colloids and Surfaces B: Biointerfaces
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c o l s u r f b
harmacokinetics of curcumin-loaded PLGA and PLGA–PEG blend nanoparticles
fter oral administration in rats
ajeh Maissar Khalil , Thuane Castro Frabel do Nascimento , Diani Meza Casa , Luciana Facco Dalmolin ,
na Cristina de Mattos, Ivonete Hoss, Marco Aurélio Romano, Rubiana Mara Mainardes ∗
epartment of Pharmacy, Universidade Estadual do Centro-Oeste/UNICENTRO, Rua Simeão Camargo Varela de Sá 03, 85040-080 Guarapuava, PR, Brazil
r t i c l e i n f o
rticle history:
eceived 2 March 2012
eceived in revised form 10 June 2012
ccepted 12 June 2012
vailable online 28 June 2012
eywords:
urcumin
C–MS/MS
ioavailability
anoparticles
a b s t r a c t
The aim of this study was to assess the potential of nanoparticles to improve the pharmacokinetics of
curcumin, with a primary goal of enhancing its bioavailability. Polylactic-co-glycolic acid (PLGA) and
PLGA–polyethylene glycol (PEG) (PLGA–PEG) blend nanoparticles containing curcumin were obtained
by a single-emulsion solvent-evaporation technique, resulting in particles size smaller than 200 nm. The
encapsulation efficiency was over 70% for both formulations. The in vitro release study showed that cur-
cumin was released more slowly from the PLGA nanoparticles than from the PLGA–PEG nanoparticles. A
LC–MS/MS method was developed and validated to quantify curcumin in rat plasma. The nanoparticles
were orally administered at a single dose in rats, and the pharmacokinetic parameters were evaluated
and compared with the curcumin aqueous suspension. It was observed that both nanoparticles formu-
lations were able to sustain the curcumin delivery over time, but greater efficiency was obtained with
the PLGA–PEG nanoparticles, which showed better results in all of the pharmacokinetic parameters ana-
lyzed. The PLGA and PLGA–PEG nanoparticles increased the curcumin mean half-life in approximately 4
and 6 h, respectively, and the Cmax of curcumin increased 2.9- and 7.4-fold, respectively. The distribution
and metabolism of curcumin decreased when it was carried by nanoparticles, particularly PLGA–PEG
nanoparticles. The bioavailability of curcumin-loaded PLGA–PEG nanoparticles was 3.5-fold greater than
the curcumin from PLGA nanoparticles. Compared to the curcumin aqueous suspension, the PLGA and
PLGA–PEG nanoparticles increased the curcumin bioavailability by 15.6- and 55.4-fold, respectively.
These results suggest that PLGA and, in particular, P.
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
This document summarizes a study that explored using an aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and sodium citrate to purify lectin from Canavalia grandiflora seeds. A 24 full factorial design was used to study how four factors (PEG molar mass, PEG concentration, pH, and citrate concentration) affected the partitioning of the lectin ConGF. The results showed that ConGF preferentially partitioned to the PEG-rich top phase. A system of 20% PEG 400 and 20% citrate at pH 6 allowed recovery of ConGF with an 8.67 partitioning coefficient and 104% yield, demonstrating the efficiency of this ATPS for pur
Intranasal delivery of drug loaded thiolated co-polymeric microparticles for...Gaurav Patil
E-Presentation at Two days 15th Indo-US virtual International Conference
on “Global advances in Pharmaceutical and Allied Science”
In collaboration with
APP Gujarat State branch, AAP American International branch,
AAP Pharmedu Healthcare Manag Division
This document describes a study that evaluated the use of anion exchange chromatography to purify polyclonal immunoglobulin G (IgG) antibodies from rabbit serum. Two anion exchangers - DEAE and Q XL - were tested for their ability to remove albumin from rabbit serum while retaining IgG. The optimal conditions for albumin removal using DEAE were a pH of 8.0 and initial protein concentration of 0.5 mg/ml. Under these conditions, DEAE removed over 90% of albumin with less than 20% IgG loss, yielding 80% of IgG at 83% purity. Q XL also removed 90% of albumin but yielded only 70% of IgG at 62% purity. Therefore, DEAE
The document discusses poly(lactic-co-glycolic acid) (PLGA), a biodegradable polymer. It provides details on the synthesis of PLGA from lactide and glycolide monomers, its properties such as solubility and glass transition temperature, and its biodegradation process. Applications of PLGA include drug delivery systems, medical implants, and tissue engineering scaffolds. Case studies show that modifying PLGA with other polymers or peptides can improve drug permeability and distribution in tissues.
New tools bring greater understanding to cellular metabolism research Mourad FERHAT, PhD
Presentation of Promega Solutions in the field of cellular Metabolism research. Discover new bioluminescent assays for the detection of several metabolites and metabolic process such as : Glucose Uptake, Glucose consumption, Lactate secretion and Glutamine/Glutamate metabolism.
1. The document analyzes the degradation of PLGA and PGA-co-PDL polymeric nanoparticles (NPs) in simulated lung fluid (SLF) for pulmonary drug delivery applications.
2. Results showed PLGA NPs reduced in size over time, indicating degradation, while PGA-co-PDL NPs aggregated and increased in size.
3. PLGA NPs produced a more acidic environment as they degraded, which could potentially cause more inflammation than PGA-co-PDL NPs in vivo.
Formulation and characterization of epigallocatechin gallate nanoparticlesRamkumar Ponnuraj
This document describes the formulation and characterization of Epigallocatechin gallate (EGCG) nanoparticles. EGCG was encapsulated in chitosan nanoparticles using ionic gelation with sodium tripolyphosphate to improve its bioavailability. Different ratios of EGCG to chitosan were tested, and a 1:0.5 ratio showed the highest drug loading and encapsulation efficiency. The resulting nanoparticles were spherical with a size range of 198-385 nm. In vitro drug release and characterization studies demonstrated the nanoparticles were a promising delivery system for EGCG with improved absorption.
1) The document describes a study that encapsulated the growth factor BMP-2 within PLGA/PLGA-PEG-PLGA microparticles to develop a delivery system for sustained release of BMP-2.
2) Characterization showed the microparticles were spherical with a mean diameter of 98 μm and encapsulation efficiency of 57%. In vitro release studies demonstrated sustained release of BMP-2 from the microparticles over 2 weeks without an initial burst release.
3) Cell culture experiments showed the released BMP-2 was bioactive and promoted greater osteogenic differentiation of MC3T3-E1 cells than osteogenic supplements, as demonstrated by increased alkaline phosphatase activity and mineralization.
PROTAC Delivery System Recent Research Advances.pdfDoriaFang
The combination of PROTAC and multifunctional delivery systems will open up new research directions in the field of TPD. Here we will introduce the combination of PROTAC and multifunctional delivery systems.
1) The document describes a novel method called INLIGHTTM for the relative quantification of N-linked glycans using isotopically labeled glycan hydrazide tags.
2) The method involves releasing N-linked glycans from glycoproteins using PNGase F, then derivatizing the glycans from two samples with either a light or heavy tagged reagent.
3) The tagged glycans are mixed, analyzed by LC/MS, and ratios of light and heavy glycan pairs are calculated to quantify differences between the two samples after correcting for isotopic overlap.
This document describes a method for fabricating porous poly(DL-lactic-co-glycolic acid) (PLGA) microspheres that fuse together at body temperature to form solid porous scaffolds, creating an injectable scaffold system. The microspheres were treated with ethanolic sodium hydroxide to increase surface porosity without disintegrating. When mixed with media and incubated at 37°C, the microspheres fused to form scaffolds with compressive strength of 0.9 MPa, porosity of 81.6%, and pore diameter of 54 μm, supporting NIH-3T3 cell attachment and proliferation in vitro. This study demonstrates a technique for producing an injectable and porous PLGA scaffold that solid
Mutations that reduce outer membrane permeability in Escherichia coli lead to increased tolerance of the bacterium to the antimicrobial lactoperoxidase enzyme system. The study identified two E. coli mutants with increased tolerance to lactoperoxidase due to mutations in genes involved in lipopolysaccharide synthesis. These mutants had reduced amounts of porins in their outer membrane, indicating decreased outer membrane permeability. Knockout mutants of specific porin genes also showed increased tolerance, suggesting the antimicrobial activity of lactoperoxidase relies on uptake of its oxidized substrates through porins.
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.
This document investigates how the composition of lipid vesicles (LUVs) affects their leakage when exposed to epigallocatechin gallate (EGCg), an antioxidant found in green tea. A fluorescence assay was used to quantify the leakage of carboxyfluorescein encapsulated in LUVs with varying lipid compositions after treatment with EGCg. The results showed that incorporating negatively charged lipids or lipids that increase membrane viscosity, such as cholesterol and POPE, reduced EGCg-induced leakage of the LUVs. This suggests that the interaction between EGCg and lipids, which leads to membrane disruption, is influenced by lipid charge and fluidity.
Fibrous Scaffold Produced By Rotary Jet Spinning TechniqueIJERA Editor
This document describes research on producing fibrous scaffolds using a rotary jet spinning technique with poly(L-lactic acid) and poly(ɛ-caprolactone) polymers. Specifically:
- PLLA/PCL meshes were produced using rotary jet spinning and characterized through SEM imaging, thermal analysis, FTIR spectroscopy, and in vitro cell culture tests.
- SEM images showed the production of fibers without beads for compositions with more PLLA or equal proportions of PCL. Thermal analysis indicated the immiscible property of the PLLA/PCL blend and complete solvent evaporation. In vitro tests found no signs of cell toxicity, indicating biocompatibility.
- The research aims
This document summarizes a study that developed an optimized process for the sustainable bioproduction of the blue pigment indigoidine by the yeast Rhodosporidium toruloides. Key findings include:
- R. toruloides was engineered to produce indigoidine, achieving a high titer of 85 g/L from glucose and demonstrating production from renewable carbon sources like sorghum hydrolysates.
- This represents the first heterologous production of a non-ribosomal peptide (NRP) in R. toruloides, extending the range of microbial hosts that can produce NRPs sustainably.
- Production of indigoidine demonstrates an alternative biobased route
2. hydrophilic or amphiphilic polymers such as poly(ethylene glycol)
(PEG) and chitin [7–10]. Previously, a linear release profile of ovalbumin
(OVA) in a 30-day time period was obtained from microparticles
(~10 μm) produced from blends of PLGA 50:50 (molecular weight of
35,000 Da) and PEG (molecular weight of 8000 Da) (PLGA:PEG ratio
of 1:3 and 1:2) [11].
The application of PLGA–PEG–PLGA (or PLGA–PEO–PLGA) triblock
copolymers in controlled drug delivery has been extensively studied
mainly as hydrogels [12–19]. These triblock copolymers have accept-
able biocompatibility and therefore are suitable for use as biomaterials
and medical devices [20–22]. PLGA–PEG–PLGA triblock copolymers
hold physicochemical properties that have the potential to overcome
the problems associated with protein release from PLGA-based delivery
systems. These properties include higher hydrophilicity, accelerated
degradation and faster pore formation. Blending PLGA–PEG–PLGA tri-
block copolymers with PLGA polymer show potential as a tool to accel-
erate the release of bioactive molecules from delivery systems [23,24].
In this study, two different PLGA–PEG–PLGA triblock copolymers were
synthesized and their interaction with water was investigated by study-
ing the sol–gel behavior of the aqueous solution. These two triblock
copolymers were used in the fabrication of large size microparticles
(100–300 μm). Four different microparticle groups with formulations
containing different masses of triblock (10% and 30% w/w) have been
compared to a formulation with no triblock i.e. PLGA 85:15. PLGA 85:15
used here was an ester ending polymer with Mw of 118 kDa and a glass
transition temperature (Tg) of around 56 °C. Slow degradation rate and
slow release profile are generally attributed to high molecular weight
and high LA/GA ratio of the polymer used [5,25,26]. The Tg of the above
four microparticle groups was measured using rheology. The triblock co-
polymers were used to decrease the Tg of the polymer formulations and
the effect of each triblock copolymer on the Tg was investigated. Mor-
phology and size distribution of microparticles were studied via scanning
electron microscopy and laser diffraction. Lysozyme was used as a model
protein to study its release kinetics from microspheres produced from
PLGA 85:15 blended with PEG-containing triblocks. To study the release
behavior of each microparticle group a continuous flow system was
used. The effect of each of the PLGA–PEG–PLGA triblock copolymers on
the release of lysozyme from microparticles over a 60-day period was in-
vestigated separately.
2. Materials and methods
2.1. Materials
All materials are used without further modification and or purifica-
tion unless otherwise stated. Poly(ethylene glycol) with Mw of 1500
(PEG 1500), poly(ethylene glycol) with Mw of 1000 (PEG 1000), stan-
nous 2-ethylhexanoate (stannous octoate), lysozyme from chicken
egg white (EC 3.2.1.17), polyvinyl alcohol (PVA) (Mw: 13–23 kDa, 87–
89% hydrolyzed), sodium hydroxide (NaOH), and sodium dodecyl
sulfate (SDS) were purchased from Sigma-Aldrich, UK. Poly(ethylene
glycol) Mw of 6000 (PEG 6000) was obtained from BHD Chemicals
and D,L-lactide (LA) from Alfa Aeser, UK. Glycolide (GA) was purchased
from PURAC, Gorinchem, Netherlands. Micro bicinchoninic acid (μ-BCA)
kit was obtained from ThermoScientific, UK. Poly(DL-lactide-co-
glycolide) (PLGA) 85:15 (ester ending, Mw 118 kDa, inherent viscosity
0.6–0.8) was purchased from Lakeshore Biomaterials, Alabama, USA.
Dichloromethane (DCM) and dimethylsulfoxide (DMSO) were obtained
from Fisher Scientific, UK. Deuterated chloroform (CDCl3) was pur-
chased from Cambridge Isotope Laboratories, MA, USA.
2.2. Synthesis of PLGA–PEG–PLGA triblock copolymers
Two different triblock copolymers were synthesized via ring open-
ing polymerization using PEG1500 and PEG1000 following the method
previously described [27]. In brief, the PLGA–PEG1500–PLGA triblock
reaction mixture was composed of 5.5 g PEG1500, 9.57 g of LA and
3.08 g of GA (LA:GA molar ratio on feed was 2.5). For synthesis of
PLGA–PEG1000–PLGA triblock 5.5 g PEG 1000, 9.97 g LA and 2.68 g
GA (LA:GA molar ratio on feed was 3) were used. The PEG component
was dehydrated for 3 h at 120 °C and polymerization was continued
for 8 h under argon atmosphere at 150 °C.
2.3. Characterization of PLGA–PEG–PLGA triblock copolymers
2.3.1. 1
H NMR characterization
Proton magnetic nuclear resonance (1
H NMR) was used to charac-
terize the triblocks. Spectra were recorded at 400 MHz on a Bruker
spectrometer at 25 °C. Triblocks were dissolved (10–30 mg/ml) in deu-
terated chloroform (CDCl3) containing tetramethylsilane (TMS). The
TMS signal was taken as zero chemical shift. Number average molecular
weight (Mn) and lactide to glycolide ratio were determined by integra-
tion of the peak signals pertaining to each monomer, such as CH2 of
glycolide, CH of lactide, and CH2–CH2 of ethylene glycol.
2.3.2. Molecular weight evaluation
Gel permeation chromatography (GPC) was used to determine the
weight average molecular weight (Mw) and molecular weight distribu-
tion of the triblocks. The analysis was performed using a PL-GPC 50
apparatus at 25 °C. Triblocks were dissolved (10–15 mg/ml) in HPLC
grade chloroform (CHCl3). The triblock solutions were filtered using a
0.2 μM Ministar-RC syringe filter unit (Sartorius, Epsom UK) into 2 ml
GPC vials. The analysis was performed using chloroform as eluent at a
flow rate of 1 ml/min; GPC was calibrated with polystyrene standards.
Two PL Gel Mixed-D (5 μm) (7.8 × 300 mm) columns were used for
higher resolution. Mw, Mn and polydispersity obtained directly from
GPC and reported directly.
2.3.3. Rheological evaluation of aqueous solution of PLGA–PEG–PLGA
triblock copolymers
Rheological measurements were performed using a dynamic mechan-
ical analysis rheometer (Anton Paar, Physica MC301). Aqueous solution of
PLGA–PEG–PLGA triblock copolymers with different concentrations
namely 20, 25, 30 and 35 (%) (w/v) was prepared by addition of the
appropriate amount of each triblock copolymer to distilled water (5 ml)
and stirred at 4 °C until dissolution. Samples were placed between the
25 mm diameter parallel plates with a gap distance of 0.4–0.5 mm. To
study the rheological behavior of the triblock copolymer aqueous solu-
tions, 200 μl of each solution was used. Data were collected under
controlled oscillation. Rheology experiments were performed using an
environmental chamber exerting air pressure of 5 bar to initiate the appa-
ratus and nitrogen atmosphere 200 In/h throughout the experiment. The
temperature changes were controlled using a water bath. A Peltier hood
was used to control the temperature inside more accurately and provide
a homogenous environment when the parallel plates (25 mm diameter;
PP25) were in operation.
2.4. Lysozyme-loaded microparticles
2.4.1. Production of lysozyme-loaded microparticles
To produce lysozyme-loaded microparticles, lysozyme was first mi-
cronized via method previously described [28]. Briefly, PEG 6000
(60 mg) was added to glass vial and dissolved in 1 ml distilled water.
Chicken egg lysozyme (50 mg) was added to the solution and mixed
thoroughly. The PEG/lysozyme solution was frozen using liquid nitro-
gen and freeze dried for 48 h.
Lysozyme-loaded microparticles were produced using a solid-in-oil–
water (S–O–W) method as described by Mortia et al. [29]. This method
was optimized to produce a particle size range of 100–300 μm. In total,
four different polymer blend formulations were used for preparation of
microparticle groups. This was performed by mixing the appropriate
amount of PLGA 85:15 and the PLGA–PEG–PLGA of interest. To produce
231R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236
3. microparticle groups, PLGA/triblock blends (1 g) were dissolved in 3 ml
DCM at 25 °C in a glass vial. Micronized lysozyme was also dissolved in
DCM (1 ml). The PEG/lysozyme solution was added to PLGA/PLGA–
PEG–PLGA solution. To emulsify, 4 ml PVA solution (0.3% (w/v)), was
added and mixed using a vortex mixer VM20 mixer (Chiltern Scientific,
Bucks, UK) and stabilized for 3–4 h in PVA solution (0.3% (w/v)), after
which, the hardened microparticles were washed, sieved and separated
by a Retsch AS200 sieve shaker (amplitude 1.40, 40 s interval time for
20 min). Microparticles in the 100–300 μm size range were collected.
PLGA 85:15 without triblock was also loaded with micronized lysozyme
as a control. Another control group was prepared by fabrication of non-
loaded microparticles from PLGA 85:15 with no triblock copolymer.
2.4.2. Measurement of entrapment efficiency
To measure entrapment efficiency (EE), the protein content of micro-
particles was determined by a method previously described [30]. Briefly,
Fig. 1. A) The chemical structure of PLGA–PEG–PLGA triblock copolymer; B) the 1
H NMR spectrum of PLGA–PEG1500–PLGA triblock copolymer; C) the 1
H NMR spectrum of PLGA–
PEG1000–PLGA triblock copolymer. The 1
H NMR spectra are plotted as a signal intensity versus chemical shift (ppm: proton precession magnetometer), where the signal peaks are
(a) CH3 of LA, (b) CH2 of ethylene glycol, (c) CH2 of GA and (d) CH of LA.
232 R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236
4. 10 mg of lysozyme-loaded microspheres was weighed out and dissolved
in 750 μl DMSO by shaking for 1 h at RT, followed by addition of 2150 μl of
0.2% NaOH/0.02% SDS solution, and was shaken for 1 h at room tempera-
ture (RT). The protein content was then determined by μ-BCA kit accord-
ing to the instructions of the manufacturer. Briefly, supernatant (150 μl)
and μ-BCA kit solution mix (100 μl) were incubated in a 96 well plate
for 1 h at 36 °C after which measurement of the absorbance at 562 nm
was performed using a TECAN Infinite 200 plate reader. To calculate the
protein content each absorbance value was correlated to values obtained
from a standard curve prepared from serial dilution of lysozyme concen-
tration (0–200 μg/ml). Only values which were within the linear range of
the standard curve were used. Samples which there initial values were
above the limit were diluted 2 or 4 times and re-measure accordingly
and samples with values lower than this limit were considered immea-
surable and not included.
2.4.3. Determination of the glass transition temperature of
polymer formulations
To study the change in the Tg of polymer formulations as a function
of blending with PLGA–PEG–PLGA triblock copolymers, rheology was
performed on melted microparticles. Rheoplus software was used to
collect the data. This experiment was performed on all five lysozyme
loaded microparticle groups. Microparticles produced from a polymer
formulation having PLGA 85:15 were used as control group. Microparti-
cles from each group (300–400 mg) were transferred to the center of
the Peltier plate. Microparticles were melted by increasing the temper-
ature to 100–150 °C. Storage and loss moduli and phase angle were col-
lected under controlled oscillation; angular frequency (ω) 1 rad/s;
amplitude of 1%, and heating rate of 2 °C/min and 0.1% strain. The tem-
perature ramp was 10 to 80 °C with 35 measuring points. Each sample
was run three times.
2.4.4. Scanning electron microscopy (SEM) of microparticles
To study the morphology of microparticles a variable pressure SEM
(JEOL 6060LV, Jeol Ltd., UK) was used. Microparticles were sputter-
coated on an adhesive stub with gold under argon atmosphere (Balzers
SCD 030 Gold Sputter Coater, Liechtenstein) prior to examination.
2.4.5. Determination of the size distribution of microparticles
A laser diffraction method was used to study the size distribution of
microparticles. A Coulter LS230 apparatus (Beckman Coulter, UK) was
set to use a garnet.rfd optical model. Microparticles (50 mg/ml) were
suspended in HPLC grade (HPLC Grade Elga) water and size distribution
was recorded after obtaining an obscuration of 8–12% under constant
stirring.
2.5. Lysozyme release kinetics
To study the release of entrapped lysozyme from microspheres a set-
up previously described by Aubert-Pouessel et al. was employed [31].
Briefly, lysozyme-loaded microparticles (50 mg) were placed into an
Omega Column tube (Presearch Ltd., UK). Each end was covered by
two 0.5 μm PEEK frits (Presearch Ltd., UK). PEEK material is resistant to
protein adhesion [31]. One end was connected to a 20 ml Plastipak
syringe using a 1/16″ OD (0.04″ ID) HPLC PEEK tube that was fixed to a
Harvard PHD 2000 infusion pump. The other end of the tube was connect-
ed to a 15/50 ml centrifuge tube using the same HPLC PEEK tube. The in-
fusion pump was set to provide a continuous infusion rate of 2.0 μl/min.
Phosphate buffered saline (PBS) (pH 7.4), was used as eluent buffer.
The release study was set up within a temperature-controlled incubator
(37 °C). The samples were collected each 24 h in the first week and
each 48 to 72 h after that. Supernatant was stored at 4 °C and its protein
content was quantified using the μ-BCA kit following the procedure
explained in Section 2.4.2.
3. Results and discussion
3.1. 1
H NMR characterization and molecular weight evaluation
Bi-functional (α,ω-dihydroxy-terminated) PEGs with molecular
weights of 1000 Da and 1500 Da were used to synthesize two composi-
tionally different triblock copolymers via ring opening polymerization
from D,L-lactide and glycolide. 1
H NMR spectrometry revealed the
chemical structure of the synthesized triblocks. The signals pertaining
to PLGA–PEG–PLGA are 5.20 ppm for CH of LA, 1.55 ppm for CH3 of
LA, 4.80 ppm for CH2 of GA, and 3.65 ppm for CH2–CH2 of PEG and are
shown in Fig. 1. The peaks representing CH of LA, CH2 of GA, and CH2–
CH2 of PEG were used for calculation of number average molecular
weight (Mn) and LA:GA ratios. The spectra obtained were similar to
previously reported spectrum [12]. The structural characteristics calcu-
lated from 1
H NMR data are summarized in Table 1. Molecular weight
and molecular weight distribution of the triblocks were evaluated
using GPC. The peaks in the chromatograms represented the triblock
copolymers were obtained at the retention time of about 15–16 min.
Uni-modal, relatively symmetric and narrow peaks in both chromato-
grams were obtained that confirm a narrow molecular weight distribu-
tion (data not shown). The quantitative data obtained from GPC analysis
of the triblock copolymers is summarized in Table 1.
These data (Table 1) demonstrated the difference between the two
triblock copolymers synthesized in terms of Mw and LA:GA ratio. The
Mw and Mn of the triblock containing PEG 1500 were higher than the
one containing PEG 1000 and these were confirmed both by 1
H NMR
and GPC. These differences resulted in different interactions with
water when they are dissolved, as explained in Section 3.2 below.
3.2. Rheological evaluation of aqueous solution of triblock copolymers
Rheological characterization of the aqueous solution of PLGA–PEG–
PLGA triblock copolymers synthesized here revealed that both triblock
copolymers demonstrated a thermo-reversible sol–gel transition
(Table 2). It was shown that aqueous solution of PLGA–PEG1500–
PLGA triblock copolymer possesses a gel window of 33–43 °C and the
gel window for PLGA–PEG1000–PLGA triblock copolymer was found
to be between 10 and 16 °C. The sol–gel transition temperatures for
Table 1
Summary of 1
H NMR and GPC results for the PLGA–PEG–PLGA triblock copolymers.
Triblock copolymer On feed NMR GPC
LA/GAa
Mnb
LA/GAc
Mnd
Mwe
PDI
PLGA–PEG1500–PLGA 2.5 2043–1500–2043 3.1 3437 4757 1.38
PLGA–PEG1000–PLGA 3 1443–1000–1443 4.2 1981 2617 1.32
a
Molar ratio of lactic acid to glycolic acid on feed.
b
Number average molecular weight calculated from 1
H NMR data.
c
Molar ratio of lactic acid to glycolic acid calculated from 1
H NMR data.
d
Number average molecular weight determined by GPC.
e
Weight average molecular weight determined by GPC.
Table 2
Comparison of sol–gel temperature and gel window for different concentrations of aque-
ous solutions of triblock copolymers.
Triblock copolymer Sol–gel temp. (°C) Gel–sol temp. (°C) Gel window (°C)
PLGA–PEG1500–PLGA
20% w/v 33.5 40.8 7.3
25% w/v 33.5 41.0 7.5
30% w/v 33.0 41.0 7.9
35% w/v 33.5 40.3 6.7
PLGA–PEG1000–PLGA
20% w/v 10.0 16.3 6.3
25% w/v 10.5 16.0 5.5
30% w/v 10.8 15.5 4.7
35% w/v 11.3 15.0 3.7
233R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236
5. PLGA–PEG1500–PLGA and PLGA–PEG1000–PLGA were found to be
~33 °C and ~10 °C, respectively. The higher sol–gel transition tempera-
ture of PLGA–PEG1500–PLGA can be attributed to higher hydrophilicity
of this polymer. It was shown that lower sol–gel transition temperature
is associated with higher hydrophobicity [12]. The gel window of PLGA–
PEG1500–PLGA encompassed the physiological and experimental tem-
perature; i.e. 37 °C. On the other hand, the gel window of PLGA–
PEG1000–PLGA spanned over a distinctively lower temperature range.
The rheological evaluation of the aqueous solution of triblock copoly-
mers showed that these two compositionally different triblock copoly-
mers also interact with water distinctively.
3.3. Size distribution, entrapment efficiency and morphology
Size distribution, entrapment efficiency and morphology are
amongst the most important characteristics of microparticles. Size
distribution is one of the factors that govern the release behavior of
microparticles [32,33]. In this study we have narrowed the size dis-
tribution of microparticles by sieving to be able to minimize the ef-
fect of microparticle size distribution on release behavior. The
mean diameter of the microparticles used for this study was all ap-
proximately 200 μm for microparticles with polymeric formulations
containing triblocks and around 300 μm for microparticles with no
triblocks. There was no statistical difference between the microparti-
cle sizes (Table 3). It has been demonstrated that size-fractionated
PLGA microspheres show different release profiles [34]. It was also
postulated that there is a correlation between microparticle size
and release rate [6].
Measurement of entrapment efficiency (EE) would indicate the mass
of protein encapsulated in the microparticles. The method used here [30]
is based on dissolution of the polymer matrix in DMSO followed by mea-
surement of the encapsulated protein released into the alkaline environ-
ment. The entrapment efficiency of all five microparticle groups is
represented in Table 3. The EE of the four microparticles groups contain-
ing PLGA–PEG–PLGA in their formulation appeared to be similar and
lower than the control group. This can be attributed to the hydrophilicity
imposed by the presence of the PLGA–PEG–PLGA triblock copolymer in
the four test groups and its absence in the control group; in the sense
that during the hardening the hydrophilicity of the test group formulation
would attract more water to the polymer matrix and therefore the diffu-
sion of protein moieties to the aqueous environment would be higher.
This results in lower EE in this microparticle group.
Scanning electron microscopy (SEM) was used to examine micro-
particle morphology. SEM images show that all the particles possess
smooth surfaces (Fig. 2) with very few pores. For both PLGA–PEG–
PLGA formulations, it was observed that blending any of the triblock co-
polymers with PLGA 85:15 did not affect the morphology of the
resulting microparticles with respect to the control group (microparti-
cles produced from pure PLGA 85:15). This can be attributed to the
structural similarity of the triblock copolymers with each other and
with the PLGA [35].
For tissue engineering purposes, these microparticles could be used
in combination or singularly depending on the tissue and the intended
indication. Sequential release of multiple growth factors is shown to
be a critical factor in neo-tissue formation and being able to pre-
program the release would be achievable using this approach.
3.4. Evaluation of the glass transition temperature of polymer formulations
Glass transition temperatures of microparticle melts were measured
using a rheometer. The glass transition temperature is the temperature
at which the storage modulus declines and becomes lower than the loss
modulus as the temperature is increased. The temperature at which the
glass transition occurs in the microparticle group produced from PLGA
85:15 without any triblock – that is 56 ± 1.2 °C – is shown in Fig. 3 as
a representative. The values for microparticles produced from formula-
tions containing 10% and 30% w/w PLGA–PEG1500–PLGA were 48.6 ±
2.4 °C and 40 ± 1.4 °C, respectively. The glass transition temperature
for microparticles with 10% and 30% w/w PLGA–PEG1000–PLGA was
49 ± 1.7 °C and 39.7 ± 2.4 °C, respectively. These data show a correla-
tion between the percentage of PLGA–PEG–PLGA present in the poly-
mer formulation and the Tg (Fig. 3) — in such a way that an increase
in the triblock content of the polymer formulation decreased the glass
transition temperature of the microparticles. In Fig. 3, there appears to
be no difference between PLGA–PEG1500–PLGA and PLGA–PEG1000–
PLGA in terms of the effect on the Tg of microparticles in a like-for-
like comparison. The high Tg observed in the microparticle group pro-
duced from PLGA 85:15 can be attributed to the strong non-covalent
Table 3
Summary of microparticle size characterization and corresponding entrapment efficiencies (n = 3).
Microparticle polymer formulation Mean ± STD μm Entrapment ± STD %
PLGA 85:15; 7E/PLGA–PEG1000–PLGA 90:10 229 ± 76 65 ± 4.2
PLGA 85:15; 7E/PLGA–PEG1000–PLGA 70:30 216 ± 50 68 ± 6.1
PLGA 85:15; 7E/PLGA–PEG1500–PLGA 90:10 222 ± 50 72 ± 4.6
PLGA 85:15; 7E/PLGA–PEG1500–PLGA 70:30 203 ± 71 64 ± 7.6
PLGA 85:15 296 ± 30 85 ± 8.3
Fig. 2. Representative scanning electron micrograph (SEM) of microparticles fabricated from PLGA85:15 i.e. control group (left) and from PLGA 85:15 containing 30% w/w PLGA–
PEG1000–PLGA (right).
234 R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236
6. interactions between the polymer cross-linkages that can absorb ther-
mal energy. The decrease in the Tg in other microparticle groups can
be attributed to the presence of PLGA–PEG–PLGA triblock that would
decrease the strength of the non-covalent interactions between poly-
mer cross-linkages by imposing heterogeneity in the polymeric net-
work. These results show that blending PLGA with PLGA–PEG–PLGA
(30% w/w) decreased the Tg to temperatures close to physiological tem-
perature. The proximity of the glass transition temperature to physio-
logical temperature will affect the viscoelastic behavior of the polymer
matrix in microparticles and therefore influence the release kinetics of
bioactive molecules. Increasing the temperature of the environment
was shown to enhance drug diffusion as a function of polymer mobility.
Previously, a threefold increase in drug diffusion coefficient had been
reported at temperatures near the Tg [36]. It was shown that progester-
one release was faster at temperatures above the Tg of PLA-based
microparticles and no significant release occurred below the Tg during
the period of study; at temperatures above the Tg, drug release rates
increase with increase in the temperature [37].
3.5. In vitro release of lysozyme
In this study, the effect of each PLGA–PEG–PLGA triblock copolymer
on the release of lysozyme from PLGA 85:15-based microparticles was
investigated. In the control group i.e. microparticles with no triblock co-
polymer a total release of 5.6% (121.4 μg) after 60 days was obtained.
Very slow release kinetics is usually expected from PLGA 85:15 [38,39]
which is attributed to its predominantly hydrophobic structure and in
this case specifically, also attributed to the ester ending and high molec-
ular weight (Fig. 4). The release profile shows that incorporation of
PLGA–PEG1000–PLGA has accelerated lysozyme release the same as
Fig. 3. A) Representative rheology profile of microparticle melts. The graph shows the rheological behavior of PLGA 85:15. The vertical arrow shows the approximate Tg of polymer for-
mulation (56 ± 1.2 °C) (n = 3). B) The effect of blending with triblock copolymers on the Tg of microparticles.
Fig. 4. The cumulative release profiles of microparticles in percent. The profiles obtained from 50 mg microparticles (n = 3). Cumulative STD is calculated based on running some of individual
STDs. The profile shows that 70% of entrapped protein is released after 30 days from microparticles with PLGA85:15/PLGA–PEG1500–PLGA 70:30 (■) and PLGA85:15/PLGA–PEG1000–PLGA
70:30 (□) formulations. Nearly 40% of entrapped protein is released from microparticles with PLGA85:15/PLGA–PEG1500–PLGA 90:10 (▲) and PLGA85:15/PLGA–PEG1000–PLGA 90:10 (Δ)
formulations. The significant difference (P b 0.05) in the release from 30 and 10% triblock containing formulations was observed after day 10. This figure shows the non-significant difference
in the release profile of microparticles fabricated from PLGA 85:15 blended with PLGA–PEG1000–PLGA compared to PLGA–PEG1500–PLGA. Data represent the mean (n = 3) and error bars
represent cumulative standard deviation (error bars not visible are smaller than the symbol). Statistical analysis was performed using SPSS software (version 16). The paired sample t-test
and the ANOVA (general linear model (repeated measures)) were used for the comparison of means. Statistical significance was defined as p b 0.05.
235R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236
7. the PLGA–PEG1500–PLGA. Non-significant difference (P b 0.05) in the
release rates was observed from day 1 to day 10 and significant differ-
ence in release rate was observed after day 10 (P b 0.05). The release
is halted after day 30 in microparticle groups containing 30% of either
triblocks. After day 30, the release was continued in microparticle
groups containing 10% of either triblocks and was increased after day
30 that is only significantly different at one time point between days
30 and 50, however, the total release at the end of the study period
was not significantly different.
The lysozyme release was accelerated from microparticles contain-
ing 10% w/w PLGA–PEG–PLGA in their formulation. Release profiles
obtained from these formulations showed that in total 40.2% (725 μg)
and 50.9% (834 μg) lysozyme was released from these microparticles
containing PEG 1500 and PEG 1000, respectively, after 60 days. These
release profiles represent tri-phasic release profiles and resemble the
profile previously reported from microparticles produced from PLGA
50:50 (Mw 7831 Da) with free carboxyl end group in PBS [40]. The re-
lease profiles obtained here showed a shift from a bi-phasic release pro-
file in control group to a tri-phasic profile. The fact that the Tg of these
microparticle groups (~48 °C) was markedly higher than incubation
temperatures (37 °C) eliminates the possibility that the Tg is affecting
the release profiles. These release profiles can be attributed to earlier in-
duction of degradation; possibly related to or imposed by presence of
PLGA–PEG–PLGA copolymer in the formulation (Fig. 4).
Microparticle groups containing 30% w/w of either triblocks showed
gradual and continuous release of lysozyme. In total, 69.45% (1129.3 μg)
and 68.5% (1170 μg) of the entrapped protein were released after
30 days from microparticles containing PEG 1500 and PEG 1000, respec-
tively. The release was below detectable levels after day 30. These pro-
files indicate a continuous release profile. The release profiles obtained
from these microparticle groups can be attributed to the proximity of
their Tg (~39 °C) to the incubation temperature (37 °C) (Fig. 4). The
proximity of environment temperature to the Tg of these formulations,
appears to have affected the viscoelastic behavior of these formulations,
making them more viscous and therefore the diffusivity was higher in
these microparticles. Consequently, higher release rates were obtained.
Generally, polymers have more elastic behavior in temperature ranges
below their Tg [37]. On the other hand, polymers have more viscous be-
havior in temperature ranges above or equal to their Tg; and macromo-
lecular mobility is higher. Higher release rates under these conditions
can be attributed to drug diffusion through the polymer matrix or com-
bined with diffusion through water-filled pores present in the micro-
particle [39].
4. Conclusion
Here it is demonstrated that the rate of lysozyme release can be con-
trolled by blending PLGA–PEG–PLGA triblock copolymers with the
foundation polymer (PLGA). These data supports the notion that there
is a non-significant difference between PLGA–PEG1000–PLGA and
PLGA–PEG1500–PLGA in acceleration of lysozyme release from PLGA
microparticles; despite differences in the characteristic of these two tri-
block copolymers. In this work, it was shown that the release rate was
correspondent to the mass of triblock blended with the foundation
polymer. This release behavior can be attributed to Tg of the polymer
formulations. The decrease in the Tg of the polymer formulations and
earlier induction of the protein release can be attributed to the blending
of the PLGA with PLGA–PEG–PLGA triblock copolymers. It is shown that
blending the PLGA 85:15 with PLGA–PEG–PLGA triblock copolymer has
decreased the Tg of the microparticles and induced earlier and faster
lysozyme release from them. Overall, the release profiles obtained
from microparticles containing the same amount of either triblock
copolymer appears to be similar. These findings could be used to em-
ploy the properties of both the PLGA polymer and the PLGA–PEG–
PLGA triblock copolymers to program the release behavior in a way
that protein release precedes polymer degradation. This approach can
be used to produce multifunctional tissue engineering scaffolds that
serve not only as a delivery system for sequential protein release but
also as an anchorage for cells to respond to the released biomolecules
and provide an appropriate niche for the cells to grow or differentiate.
Based on the above findings, tissue engineering constructs can be fabri-
cated that release the encapsulated therapeutic protein prior to polymer
degradation; thereby, supporting cellular response to the released
biomolecule(s) by providing sufficient anchorage for cells to grow and
differentiate.
References
[1] V. Luginbuehl, L. Meinel, H.P. Merkle, B. Gander, Eur. J. Pharm. Biopharm. 58 (2004)
197–208.
[2] B.C. Clark, D.M. Cross, P.R. Gellert, R.S. Kittlety, in: W.I.P. Organization (Ed.), Method
for Determining the Release of a Peptide From a Sustained Release Polylactide For-
mulation, WIPO, UK, 2002.
[3] K.J. Whittlesey, L.D. Shea, Exp. Neurol. 190 (2004) 1–16.
[4] I. Grizzi, H. Garreau, S. Li, M. Vert, Biomaterials 16 (1995) 305–311.
[5] M. Vert, J. Mauduit, S. Li, Biomaterials 15 (1994) 1209–1213.
[6] J. Siepmann, N. Faisant, J. Akiki, J. Richard, J.P. Benoit, J. Control. Release 96 (2004)
123–134.
[7] W. Jiang, S.P. Schwendeman, Pharm. Res. 18 (2001) 878–885.
[8] E.C. Lavelle, M.K. Yeh, A.G.A. Coombes, S.S. Davis, Vaccine 17 (1999) 512–529.
[9] M. Morlock, T. Kissel, Y.X. Li, H. Koll, G. Winter, J. Control. Release 56 (1998)
105–115.
[10] F.-L. Mi, S.-S. Shyu, Y.-M. Lin, Y.-B. Wu, C.-K. Peng, Y.-H. Tsai, Biomaterials 24 (2003)
5023–5036.
[11] M.-K. Yeh, P.G. Jenkins, S.S. Davis, A.G.A. Coombes, J. Control. Release 37 (1995) 1–9.
[12] S.B. Chen, R. Pieper, D.C. Webster, J. Singh, Int. J. Pharm. 288 (2005) 207–218.
[13] B. Jeong, Y.H. Bae, S.W. Kim, Colloids Surf. B: Biointerfaces 16 (1999) 185–193.
[14] D.S. Lee, M.S. Shim, S.W. Kim, H. Lee, I. Park, T.Y. Chang, Macromol. Rapid Commun.
22 (2001) 587–592.
[15] S.M. Li, I. Rashkov, J.L. Espartero, N. Manolova, M. Vert, Macromolecules 29 (1996)
57–62.
[16] I. Rashkov, N. Manolova, S.M. Li, J.L. Espartero, M. Vert, Macromolecules 29 (1996)
50–56.
[17] C. Witt, T. Kissel, Eur. J. Pharm. Biopharm. 51 (2001) 171–181.
[18] L. Youxin, T. Kissel, J. Control. Release 27 (1993) 247–257.
[19] L. Youxin, C. Volland, T. Kissel, J. Control. Release 32 (1994) 121–128.
[20] P. Cerrai, G.D. Guerra, L. Lelli, M. Tricoli, R. Sbarbati Del Guerra, M.G. Cascone, P.
Giusti, J. Mater. Sci. Mater. Med. 5 (1994) 33–39.
[21] B. Ronneberger, T. Kissel, J.M. Anderson, Eur. J. Pharm. Biopharm. 43 (1997) 19–28.
[22] T. Kissel, Y. Li, F. Unger, Adv. Drug Deliv. Rev. 54 (2002) 99–134.
[23] R.S. Harland, N.A. Peppas, Eur. J. Pharm. Biopharm. 39 (1993) 229–233.
[24] K.E. Uhrich, S.M. Cannizzaro, R.S. Langer, K.M. Shakesheff, Chem. Rev. 99 (1999)
3181–3198.
[25] T.G. Park, J. Control. Release 30 (1994) 161–173.
[26] T.G. Park, Biomaterials 16 (1995) 1123–1130.
[27] Q.P. Hou, D.Y.S. Chau, C. Pratoomsoot, P.J. Tighe, H.S. Dua, K.M. Shakesheff, F. Rose, J.
Pharm. Sci. 97 (2008) 3972–3980.
[28] T. Morita, Y. Horikiri, H. Yamahara, T. Suzuki, H. Yoshino, Pharm. Res. 17 (2000)
1367–1373.
[29] T. Morita, Y. Sakamura, Y. Horikiri, T. Suzuki, H. Yoshino, J. Control. Release 69
(2000) 435–444.
[30] H.K. Sah, J. Pharm. Sci. 86 (1997) 1315–1318.
[31] A. Aubert-Pouessel, D.C. Bibby, M.C. Venier-Julienne, F. Hindre, J.P. Benoit, Pharm.
Res. 19 (2002) 1046–1051.
[32] B. Amsden, Pharm. Res. 16 (1999) 1140–1143.
[33] J. Panyam, M.M. Dali, S.K. Sahoo, W. Ma, S.S. Chakravarthi, G.L. Amidon, R.J. Levy, V.
Labhasetwar, J. Control. Release 92 (2003) 173–187.
[34] N.S. Berchane, K.H. Carson, A.C. Rice-Ficht, M.J. Andrews, Int. J. Pharm. 337 (2007)
118–126.
[35] S. Chen, J. Singh, Int. J. Pharm. 352 (2008) 58–65.
[36] B.S. Zolnik, P.E. Leary, D.J. Burgess, J. Control. Release 112 (2006) 293–300.
[37] Y. Aso, S. Yoshioka, A. Li Wan Po, T. Terao, J. Control. Release 31 (1994) 33–39.
[38] J.M. Anderson, M.S. Shive, Adv. Drug Deliv. Rev. 28 (1997) 5–24.
[39] N. Faisant, J. Siepmann, J.P. Benoit, Eur. J. Pharm. Sci. 15 (2002) 355–366.
[40] G. Jiang, B.H. Woo, F.R. Kang, J. Singh, P.P. DeLuca, J. Control. Release 79 (2002)
137–145.
236 R. Qodratnama et al. / Materials Science and Engineering C 47 (2015) 230–236