The Experts below are selected from a list of 26892 Experts worldwide ranked by ideXlab platform
Jorge Heller - One of the best experts on this subject based on the ideXlab platform.
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preparation characterization and in vitro evaluation of physostigmine loaded poly ortho ester and poly ortho ester poly d l lactide co glycolide blend microspheres fabricated by spray drying
Biomaterials, 2004Co-Authors: Ling Wang, Steve Ng, Chengshu Chaw, Shabbir Moochhala, Yi Yan Yang, Bin Zhao, Jorge HellerAbstract:Abstract The physostigmine-loaded poly(ortho ester) (POE), poly( dl -lactide- co -glycolide) (PLGA) and POE/PLGA blend microspheres were fabricated by a spray drying technique. The in vitro degradation of, and physostigmine release from, the microspheres were investigated. SEM analysis showed that the POE and POE/PLGA blend particles were spherical. They were better dispersed when compared to the pure PLGA microspheres. Two glass transition temperature ( T g ) values of the POE/PLGA blend microspheres were observed due to the phase separation of POE and PLGA in the blend system. XPS analysis proved that POE dominated the surfaces of POE/PLGA blend microspheres, indicating that the blend microspheres were coated with POE. The encapsulation efficiencies of all the microspheres were more than 95%. The incorporation of physostigmine reduced the T g value of microspheres. The T g value of the degrading microspheres increased with the release of physostigmine. For instance, POE blank microspheres and physostigmine-loaded POE microspheres had a T g value of 67°C and 48°C, respectively. After 19 days in vitro incubation, T g of the degrading POE microspheres increased to 55°C. Weight loss studies showed that the degradation of the blend microspheres was accelerated with the presence of PLGA because its degradation products catalyzed the degradation of both POE and PLGA. The release rate of physostigmine increased with increase of PLGA content in the blend microspheres. The initial burst release of physostigmine was effectively suppressed by introducing POE to the blend microspheres. However, there was an optimized weight ratio of POE to PLGA (85:15 in weight), below which a high initial burst was induced. The POE/PLGA blend microspheres may make a good drug delivery system.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
Tae Gwan Park - One of the best experts on this subject based on the ideXlab platform.
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hyaluronic acid modified biodegradable scaffolds for cartilage tissue engineering
Biomaterials, 2005Co-Authors: Jun Jin Yoon, Tae Gwan ParkAbstract:Hyaluronic acid (hyaluronan, HA) was immobilized onto the surface of macroporous biodegradable poly(d,l-lactic acid-co-glycolic acid) [PLGA] scaffolds to enhance the attachment, proliferation, and differentiation of chondrocytes for cartilage tissue engineering. The PLGA scaffolds were prepared by blending PLGA with varying amounts of amine-terminated PLGA-PEG di-block copolymer. They were fabricated by a gas foaming/salt leaching method. HA was chemically conjugated to the surface-exposed amine groups on the pre-fabricated scaffolds. The amount of surface exposed free amine groups was quantitatively determined by conjugating an amine-reactive fluorescent dye to the PLGA blend films. The extent of HA immobilization was also confirmed by measuring water contact angles. When chondrocytes were seeded within HA modified PLGA scaffolds, enhanced cellular attachment was observed compared to unmodified PLGA scaffolds. Furthermore, glycosaminoglycan and total collagen synthesis increased substantially for HA modified PLGA scaffolds. RT-PCR result and histological examination of the resultant cartilage tissue revealed that HA modified scaffolds excelled in inducing cartilage tissue formation in terms of collagen type II expression and tissue morphological characteristics.
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hyaluronic acid modified biodegradable scaffolds for cartilage tissue engineering
Biomaterials, 2005Co-Authors: Hyuk Sang Yoo, Jun Jin Yoon, Eun Ah Lee, Tae Gwan ParkAbstract:Hyaluronic acid (hyaluronan, HA) was immobilized onto the surface of macroporous biodegradable poly(D,L-lactic acid-co-glycolic acid) [PLGA] scaffolds to enhance the attachment, proliferation, and differentiation of chondrocytes for cartilage tissue engineering. The PLGA scaffolds were prepared by blending PLGA with varying amounts of amine-terminated PLGA-PEG di-block copolymer. They were fabricated by a gas foaming/salt leaching method. HA was chemically conjugated to the surface-exposed amine groups on the pre-fabricated scaffolds. The amount of surface exposed free amine groups was quantitatively determined by conjugating an amine-reactive fluorescent dye to the PLGA blend films. The extent of HA immobilization was also confirmed by measuring water contact angles. When chondrocytes were seeded within HA modified PLGA scaffolds, enhanced cellular attachment was observed compared to unmodified PLGA scaffolds. Furthermore, glycosaminoglycan and total collagen synthesis increased substantially for HA modified PLGA scaffolds. RT-PCR result and histological examination of the resultant cartilage tissue revealed that HA modified scaffolds excelled in inducing cartilage tissue formation in terms of collagen type II expression and tissue morphological characteristics.
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biodegradable PLGA microcarriers for injectable delivery of chondrocytes effect of surface modification on cell attachment and function
Biotechnology Progress, 2004Co-Authors: Ki Woo Chun, Jun Jin Yoon, Hyuk Sang Yoo, Tae Gwan ParkAbstract:Poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres were prepared by an oil/water emulsion solvent evaporation method to use as an injectable microcarrier for cell delivery. Three different kinds of PLGA microspheres having hydrophobic, negatively charged, and positively charged surfaces were prepared. Hydrophobic and negatively charged PLGA microspheres were prepared by using terminally capped and uncapped PLGA polymer, respectively. Positively charged PLGA microspheres were prepared by blending PLGA with PLGA-g-poly(L-lysine) graft copolymer as a surface modifying agent. Bovine chondrocytes were cultured on the three PLGA microspheres under serum conditions to comparatively evaluate cell attachment, cell proliferation, and cell function with respect to surface properties. Positively charged PLGA microspheres showed the highest cell attachment, growth, and function compared to hydrophobic and negatively charged microspheres. Surface-modified PLGA microspheres can potentially be used as an injectable delivery system for cells into a tissue defect site.
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conjugation of drug to poly d l lactic co glycolic acid for controlled release from biodegradable microspheres
Journal of Controlled Release, 1999Co-Authors: Yoon Sung Nam, Keunhyeung Lee, Tae Gwan ParkAbstract:Poly(d,l-lactic-co-glycolic acid) (PLGA) was chemically conjugated to a model drug, N-(9-fluorenylmethoxycarbonyl-N-tert-butoxycarbonyl-l-tryptophan (Fmoc-Trp(Boc)) via an ester linkage. Various coupling reaction conditions were tested to optimize the conjugation process between a hydroxyl terminal group of PLGA and a carboxylic acid group of Fmoc-Trp(Boc). Two different lactic/glycolic acid compositions of PLGA (50/50 and 75/25) were used for the conjugation. The Fmoc-Trp(Boc)-PLGA conjugates were formulated into microspheres by a solvent evaporation technique for controlled release of Fmoc-Trp(Boc) over an one month period. A linear constant release of Fmoc-Trp(Boc) and its water-soluble PLGA oligomer conjugates was observed over an extended period without any initial burst effect, while unconjugated Fmoc-Trp(Boc) encapsulated within microspheres exhibited a rapid release profile. In addition, Fmoc-Trp(Boc) release rate solely depended on the PLGA composition that affected polymer degradation rate. The release rate of Fmoc-Trp(Boc) conjugated with fast degrading 50/50 PLGA was more rapid than that conjugated with relatively slow degrading 75/25 PLGA. This study demonstrates that PLGA-drug conjugation approach is a new and novel strategy to control the drug release rate from PLGA microspheres by utilizing the chemical degradation rate of PLGA backbone.
Steve Ng - One of the best experts on this subject based on the ideXlab platform.
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preparation characterization and in vitro evaluation of physostigmine loaded poly ortho ester and poly ortho ester poly d l lactide co glycolide blend microspheres fabricated by spray drying
Biomaterials, 2004Co-Authors: Ling Wang, Steve Ng, Chengshu Chaw, Shabbir Moochhala, Yi Yan Yang, Bin Zhao, Jorge HellerAbstract:Abstract The physostigmine-loaded poly(ortho ester) (POE), poly( dl -lactide- co -glycolide) (PLGA) and POE/PLGA blend microspheres were fabricated by a spray drying technique. The in vitro degradation of, and physostigmine release from, the microspheres were investigated. SEM analysis showed that the POE and POE/PLGA blend particles were spherical. They were better dispersed when compared to the pure PLGA microspheres. Two glass transition temperature ( T g ) values of the POE/PLGA blend microspheres were observed due to the phase separation of POE and PLGA in the blend system. XPS analysis proved that POE dominated the surfaces of POE/PLGA blend microspheres, indicating that the blend microspheres were coated with POE. The encapsulation efficiencies of all the microspheres were more than 95%. The incorporation of physostigmine reduced the T g value of microspheres. The T g value of the degrading microspheres increased with the release of physostigmine. For instance, POE blank microspheres and physostigmine-loaded POE microspheres had a T g value of 67°C and 48°C, respectively. After 19 days in vitro incubation, T g of the degrading POE microspheres increased to 55°C. Weight loss studies showed that the degradation of the blend microspheres was accelerated with the presence of PLGA because its degradation products catalyzed the degradation of both POE and PLGA. The release rate of physostigmine increased with increase of PLGA content in the blend microspheres. The initial burst release of physostigmine was effectively suppressed by introducing POE to the blend microspheres. However, there was an optimized weight ratio of POE to PLGA (85:15 in weight), below which a high initial burst was induced. The POE/PLGA blend microspheres may make a good drug delivery system.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
Yi Yan Yang - One of the best experts on this subject based on the ideXlab platform.
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preparation characterization and in vitro evaluation of physostigmine loaded poly ortho ester and poly ortho ester poly d l lactide co glycolide blend microspheres fabricated by spray drying
Biomaterials, 2004Co-Authors: Ling Wang, Steve Ng, Chengshu Chaw, Shabbir Moochhala, Yi Yan Yang, Bin Zhao, Jorge HellerAbstract:Abstract The physostigmine-loaded poly(ortho ester) (POE), poly( dl -lactide- co -glycolide) (PLGA) and POE/PLGA blend microspheres were fabricated by a spray drying technique. The in vitro degradation of, and physostigmine release from, the microspheres were investigated. SEM analysis showed that the POE and POE/PLGA blend particles were spherical. They were better dispersed when compared to the pure PLGA microspheres. Two glass transition temperature ( T g ) values of the POE/PLGA blend microspheres were observed due to the phase separation of POE and PLGA in the blend system. XPS analysis proved that POE dominated the surfaces of POE/PLGA blend microspheres, indicating that the blend microspheres were coated with POE. The encapsulation efficiencies of all the microspheres were more than 95%. The incorporation of physostigmine reduced the T g value of microspheres. The T g value of the degrading microspheres increased with the release of physostigmine. For instance, POE blank microspheres and physostigmine-loaded POE microspheres had a T g value of 67°C and 48°C, respectively. After 19 days in vitro incubation, T g of the degrading POE microspheres increased to 55°C. Weight loss studies showed that the degradation of the blend microspheres was accelerated with the presence of PLGA because its degradation products catalyzed the degradation of both POE and PLGA. The release rate of physostigmine increased with increase of PLGA content in the blend microspheres. The initial burst release of physostigmine was effectively suppressed by introducing POE to the blend microspheres. However, there was an optimized weight ratio of POE to PLGA (85:15 in weight), below which a high initial burst was induced. The POE/PLGA blend microspheres may make a good drug delivery system.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
Shabbir Moochhala - One of the best experts on this subject based on the ideXlab platform.
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preparation characterization and in vitro evaluation of physostigmine loaded poly ortho ester and poly ortho ester poly d l lactide co glycolide blend microspheres fabricated by spray drying
Biomaterials, 2004Co-Authors: Ling Wang, Steve Ng, Chengshu Chaw, Shabbir Moochhala, Yi Yan Yang, Bin Zhao, Jorge HellerAbstract:Abstract The physostigmine-loaded poly(ortho ester) (POE), poly( dl -lactide- co -glycolide) (PLGA) and POE/PLGA blend microspheres were fabricated by a spray drying technique. The in vitro degradation of, and physostigmine release from, the microspheres were investigated. SEM analysis showed that the POE and POE/PLGA blend particles were spherical. They were better dispersed when compared to the pure PLGA microspheres. Two glass transition temperature ( T g ) values of the POE/PLGA blend microspheres were observed due to the phase separation of POE and PLGA in the blend system. XPS analysis proved that POE dominated the surfaces of POE/PLGA blend microspheres, indicating that the blend microspheres were coated with POE. The encapsulation efficiencies of all the microspheres were more than 95%. The incorporation of physostigmine reduced the T g value of microspheres. The T g value of the degrading microspheres increased with the release of physostigmine. For instance, POE blank microspheres and physostigmine-loaded POE microspheres had a T g value of 67°C and 48°C, respectively. After 19 days in vitro incubation, T g of the degrading POE microspheres increased to 55°C. Weight loss studies showed that the degradation of the blend microspheres was accelerated with the presence of PLGA because its degradation products catalyzed the degradation of both POE and PLGA. The release rate of physostigmine increased with increase of PLGA content in the blend microspheres. The initial burst release of physostigmine was effectively suppressed by introducing POE to the blend microspheres. However, there was an optimized weight ratio of POE to PLGA (85:15 in weight), below which a high initial burst was induced. The POE/PLGA blend microspheres may make a good drug delivery system.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
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double walled poe PLGA microspheres encapsulation of water soluble and water insoluble proteins and their release properties
Journal of Controlled Release, 2003Co-Authors: Meng Shi, Steve Ng, Chengshu Chaw, Shabbir Moochhala, S. H. Goh, Yi Yan Yang, Jorge HellerAbstract:Abstract The poly(orthoester) (POE)–poly( d,l -lactide–co-glycolide) (50:50) (PLGA) double-walled microspheres with 50% POE in weight were loaded with hydrophilic bovine serum albumin (BSA) and hydrophobic cyclosporin A (CyA). Most of the BSA and CyA was entrapped within the shell and core, respectively, because of the difference in their hydrophilicity. The morphologies and release mechanisms of proteins-loaded double-walled POE/PLGA microspheres were investigated. Scanning electron microscope studies revealed that the CyA–BSA-loaded double-walled POE/PLGA microspheres yielded a more porous surface and PLGA shell than those without BSA. The neat POE and PLGA yielded slow and incomplete CyA and BSA release. In contrast, nearly complete BSA and more than 95% CyA were released in a sustained manner from the double-walled POE/PLGA microspheres. Both the BSA- and CyA–BSA-loaded POE/PLGA microspheres yielded a sustained BSA release over 5 days. The CyA release pattern of the CyA-loaded double-walled POE/PLGA microspheres was biphasic, characterized by a slow release over 15 days followed by a sustained release over 27 days. However, the CyA–BSA-loaded double-walled POE/PLGA microspheres provided a more constant and faster CyA release due to their more porous shell. In the CyA–BSA-loaded double-walled POE/PLGA microspheres system, the PLGA layer acted as a carrier for BSA and mild reservoir for CyA. During the first 5 days, most BSA was released from the shell but only 14% CyA was left from the microspheres. Subsequently, more than 80% CyA were released in the next 25 days. The distinct structure of double-walled POE/PLGA microspheres would make an interesting device for controlled delivery of therapeutic agents.
