• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.42-47
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• 1995

Interpolymer complex formation between basic polypeptide poly(L-proline) Form Ⅱ (PLP(Ⅱ)) and acidic polypeptides poly(L-glutamic acid) (PLGA) and poly(L-aspartic acid)(PLAA) has been studied in water-methanol (1:2 v/v) mixed-solvent by viscometry, potentiometry, light scattering and circular dichroism (CD) measurements. It has been found that polymer complexes between PLP(Ⅱ) and PLGA (or PLAA) are formed via hydrogen bonding with a stoichiometric ratio of PLP(Ⅱ)/PLGA (or PLAA)=1:2 (in unit mole ratio) and that PLP(Ⅱ) forms polymer complex more favorably with PLGA than with PLAA. In addition, the minimum (for pH 5.0) and the maximum (for pH 3.2) in reduced viscosity of dilute PLP(Ⅱ)-PLGA mixed solutions are observed at 0.67 unit mole fraction of PLGA (i.e., [PLP(Ⅱ)]/[PLGA]=1/2). These findings could be explained in terms of molecular structure (or conformation) of the complementary polymers associated with the complex formation.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.416.1-416.1
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• 2002

Biodegradable PLGA microspheres(MS) have been widely studied for delivering antigens because PLGA has the characteristics of various degradation rate. In general. since MS have shown potential for single-dose vaccines. the degradation rate of PLGA is determined by their molecular weight. polymer composition, etc. We studied the influences of molecular weight of PLGA. polymer composition and surfactant on in vitro release and in vivo effects. (omitted)

• Polymer(Korea)
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• v.34 no.5
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• pp.398-404
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• 2010

We fabricated sponge and poly(lactide-co-glycolide)(PLGA) scaffolds impregnated demineralized bone particle(DBP)(DBP/PLGA) and investigated proper condition to proliferation and phenotype maintenance of intervertebral disc(IVD) cells by comparison between DBP/PLGA scaffold and DBP sponge. DBP/PLGA scaffolds were prepared by solvent casting/salt leaching. Human IVD cells were seeded in scaffolds of two types. Cell viability and proliferation according to scaffolds were analyzed by WST assay and SEM. RT-PCR was assessed to measure mRNA expression of aggrecan and type II collagen of human IVD cells. In WST assay results, cell viability in scaffolds impregnated DBP/PLGA scaffold were higher than DBP sponge. We could observe that disc cell mRNA expressed better in DBP/PLGA scaffold than DBP sponge. We concluded that the using of DBP/PLGA in terms of scaffold fabrication for bio-disc with human IVD cells is helpful growth of disc cells maintenance of phenotypes.

• Polymer(Korea)
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• v.32 no.6
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• pp.529-536
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• 2008

We manufactured poly (L-lactide-co-glycolide) (PLGA) scaffolds impregnated demineralized bone particle (DBP) and hyaluronic acid (HA) by ice-particle leaching method and tested their ability of sustained release of brain derived neurotrophic factor (BDNF). BDNF (50 and 200 ng) mixed with PLGA, DBP/PLGA, HA/PLGA and DBP/HA/PLGA scaffold. The release profiles of BDNF from BDNF loaded scaffolds were assayed using ELISA. Morphological changes of scaffolds by BDNF release were also observed by SEM. BDNF stably and sustainedly released from DBP/HNPLGA than from PLGA and DBP/PLGA scaffolds. DBP/HA/PLGA scaffolds showed the great structural changes, which demonstrated BDNF release amount from DBP/HA/PLGA scaffolds were highest in all groups. We suggest that BDNF loaded DBP/HNPLGA scaffold would be very useful for nerve regeneration.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.167-171
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• 2009

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been a useful tool as a controlled drug delivery system for peptides and proteins. Recently, porous microspheres have gained great attention as inhalation drug delivery system due to their low aerodynamic densities. Here, we report highly porous PLGA microspheres, which were prepared by using a single o/w emulsification/solvent evaporation method. Two types of porogen, i.e., (i) extractable Pluronic F127 and (ii) gas foaming salt of ammonium bicarbonate, were used to induce pores on the surface of PLGA microspheres. The respective preparation conditions on dp/cp ratio and porogen concentration were determined by the previous preliminary experiments, and other preparation factors were further optimized on the basis of PLGA Mw and porogen type. The morphological features examined by scanning electron microscope (SEM) show these porous microspheres have highly porous surface structure with a diameter range of 20${\sim}$30 ${\mu}$m. These highly porous PLGA microspheres, which have much lower density, would be a practical aerosol system for pulmonary drug delivery.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.1-4
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• 2006

Biodegradable $\beta$-tricalcium phosphate ( $\beta$-TCP)/poly(lactide-co-glycolide) (PLGA) composites were synthesized by in-situ polymerization with microwave energy. The influence of the $\beta$-TCP content in $\beta$-TCP/PLGA composites on the molecular weight, crystallinity, microstructure and mechanical properties was investigated. As the molecular weight of composites decreased, the $\beta$-TCP content increased up to 10 wt.%, while the excess addition of the $\beta$-TCP content above 10 wt.% the molecular weight increased with increasing of the $\beta$-TCP content. This behavior would be due to the superheating effect or nonthermal effect induced by microwave energy. It was found that the bending strength and Young's modulus of the $\beta$-TCP/PLGA composites was proportional to the molecular weight of PLGA. The bending strength of the $\beta$-TCP/PLGA composites ranged from 18 to 38 MPa, while Young's modulus was in the range from 2 to 6 GPa.

• KSBB Journal
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• v.17 no.1
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• pp.33-37
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• 2002

To improve in vitro release kinetic of G-CSF in PLGA microsphere, G-CSF was PEGylated with methoxy polyethylene glycol-aldehyde (mPEG-aldehyde, MW 5000). The majority of G-CSF was mono-PEGylated and it was characterized using SDS-PAGE, HPLC, and peptide mapping. The PLGA microencapsulation with the native, or PEGylated G-CSF was performed using W/O/w method, where the encapsulation efficiency was high. For the high loading of G-CSF to microsphere, G-CSF and PEGylated G-CSF were concentrated and then verified the protein stability using native gel and gel filtration chromatography. In comparison with native G-CSF, PEGylated G-CSF was released during the extended period and its maximum amount of released G-CSF was also increased.

• YAKHAK HOEJI
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• v.44 no.4
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• pp.293-299
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• 2000

Biodegradable microspheres made from poly-lactide-co-glycolide polymers have been considered as a new delivery system for single-dose vaccine. Purified tetanus toxoid (TT) was encapsulated in poly-lactide(PLA) and poly-lactide-co-glycolide (PLGA) microparticles using a solvent evaporation method in a multiple emulsion system (water-in oil-in water). The morphology of 77-loaded microparticles was spherical and the suface of them was smooth. The particle size was in a range of 2-10. Protein loading efficiency was 68-97.8%. PLGA (85:15) microparticle showed the highest efficiency. Protein release pattern was influenced by polymer molecular weight and composition. The release rate of PLA(Mw 100,000) microsphere was higher than any other microspheres. In consequence of the hydrolysis of PLGA(50:50) microspheres, environmental pH decreased from 7.4 to 5.0. The PLA, PLGA (75:25) and PLGA (85:15) microshperes showed no significant pH change. The antigenicity or n in microshperes was assayed by indirect sandwich ELISA using equine polyclonal tetanus antitoxin for capture antibody and human polyclonal tetanus antitoxin for primary antibody. The antigenicity of TT in PLA (Mw 100,000), PLGA(50:50, Mw 100,000) and PLGA (75:25, Mw 73,300) after 30 days incubation showed 54, 40.9 and 76.7%, respectively.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.109-114
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• 2006

Biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles were developed for sustained delivery of water-soluble macromolecules. PLGA nanoparticles were fabricated by spontaneous emulsification solvent diffusion method generating negatively charged particles and heterogeneous size distribution. As a model drug, blue dextran was encapsulated in PLGA nanoparticles. In addition, nanoparticles were also prepared with varying ratio of poloxamer 188 (P188) and poloxamer 407 (P407), and coating with poly(vinyl alcohol) (PVA). Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing blue dextran were studied. In vitro release of blue dextran from nanoparticles was also investigated. The surface and morphology of nanoparticles were characterized by scanning electron microscopy (SEM). In case of nanoparticles prepared with PLGA, P407, and different organic solvents, particle size was in the range of $230{\sim}320\;nm$ and zeta potentials of nanoparticles were negative. The SEM images showed that ethyl acetate is suitable for the formulation of PLGA nanoparticles with good appearance. Moreover, ethyl acetate showed higher encapsulation efficiency than other solvents. The addition of P188 to formulation did not affect the particle size of PLGA nanoparticles but altered the release patterns of blue dextran from nanoparticles. However, PVA, as a coating material, altered the particle size with increasing the PVA concentration. The nanoparticles were physically stable in the change of particle size during long-term storage. From the results, the PLGA nanoparticles prepared with various contents of poloxamers and PVA, could modulate the particles size of nanoparticles, in vitro release pattern, and encapsulation of water-soluble macromolecules.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2958-2965
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• 2015

The PLGA(Poly lactide-co-glycolide) Copolymer have been actively applied to the medical implant material as biomaterials. PLGA membrane was able to alveoloplasty with osteotomy for favorable degradation characteristics and possibilities for sustained drug delivery. In this study, PLGA membrane was prepared using phase inversion method, and examined to optical method analysis(NMR, IR), mechanical property measurement (tearing strength) and thermal characteristic analysis(DSC). In addition, the biodegradation characteristics of the PLGA membrane filled with a PBS(Phosphate Buffered Solution) of the water bath ($60^{\circ}C$) according to the degree of surface degradation in the degradation time, the pH change of the solution and change of the mass of the membrane were measured.