• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.37-46
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• 1988

Synthetic biodegradable polymers are of great interest for biomedical applications such as surgical sutures and drug delivery systems. The copolymers of ${alpha}-amino$ acids and ${alpha}-hydroxy$ matrices having the required permeability for drugs. Poly (glycine.co-lactic acid) and poly (glycine-co-glycolic acid) have been synthesized by ring-opening polymerization. Morpholine-2, 5-diane, lactide, and glycolid have been used as starting materials for polydepsipeptides. The synthesized monomers and copoylmers have been identified by NMR and FT-lR spectrophotometer. The thermal properties and glass transition temperatures ($T_g$) of the copolymers have been measured by differential scanning calorimetry. The $T_g$ values of poly (glycine-co-lactic acid) and poly (glycine co.glycolic acid) are increased with increasing mole fraction of morpholine-2, 5-dione in the copolymers.

• Polymer(Korea)
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• v.31 no.3
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• pp.228-232
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• 2007

This purpose of this study is to enhance the hydrolysis of poly (butylene succinate-co-L-lactate) (PBSL) and poly [(R) -3-hydroxybutylate] (PHB), to develop materials with advanced medical absorbability and environmental suitability. The first method involves increasing the bioabsorbability of poly (glycolic acid) (PGA) in the core of the fibrous complex, while the second method involves making a complex fiber containing PBSL and PHB in the outer layer for improving environmental degradability Improvement in the hydrolysis of PBSL and PHB due to glycolic acid occurs by hydrolytic behavior of PGA. The drawing supporting the resulting PBSL/PGA fiber was executed at $65^{\circ}C$, where the orientation is well arranged in crystal form. Obtaining a PHB/PGA complex fiber in the proper crystal orientation at $50^{\circ}C$ was not possible since the arranged crystal orientation was only identified in drawings from temperatures above $50^{\circ}C$. Also, it is necessary to execute a smooth surface to achieve an on-line drawing since unevenness occurs in the fibrous surface from an in-line drawing.

• Polymer(Korea)
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• v.31 no.3
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• pp.233-238
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• 2007

The purpose of the study is to apply composites of poly (glycolic acid) (PGA) with [poly(R) 3-hydroxybutyrate] (P3HB) or poly (butylenes succinate- co-L-lactate) (PBSL) as medical resorbable composite materials with the complement of hydrolysis rate of each component. As a result, it was confirmed that the PBSL/PGA and P3HB/PGA composite fiber were hydrolyzed in phosphate buffer solution. Also, it has been revealed that the degradation of PBSL/PGA are accelerated due to PGA producing glycolic acid which can act as a catalyst. In addition, the hydrolysis of PBSL/PGA was found to be accelerated by the presence of lipase PS. When the PBSL/PGA composite fiber was placed in the air, not much hydrolysis has proceeded. Also, it was confirmed that the P3HB/PGA composite fiber maintained proper tensile strength in the air. Therefore, these complex fibers can be adapted to use as environmentally suitable, medically absorbable composite materials.

• Journal of Biomedical Engineering Research
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• v.13 no.2
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• pp.147-154
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• 1992

Poly (glycolic aclu-co-glycine-L-lactic aclu) has been prepared by rlng opening polymerlzation. The monomer 6-methyl morpholine-2, 5-dlone was synthe-slzed by bromoproplonylation of 2 bromopropionyl bromide with glycine. Glycolide and 6-methyl morpholine-2, 5-dione have been used as starling materials for polydepsipeptides. The synthesized copolymers have been Identlrled by NMR and FT-lR spectrophotometer. The Tg value of poly(glycollc aclu-co glycine-L-tactic acld ) Is In creased with increasing mole fraction of 6-methylmorpholine-2, 5-dlone(60-$84^{\circ}C$). The glass trasltion temperature of poly(glycolic acid-co-glycine-L-lactic-acid) (62-$86^{\circ}C$) is lower than that of poly (L-lactic acrid-co-glycine-L-lactic acid ). The thermal degradation of poly( L-lactic acid-co- glycine-L-lactic acid ) Is decreased with increasing mole fraction of L-lactide. The thermal degrada pion of poly(glycolic acrid-co-91ycine-L-lactic aclu ) is increased with increasing mole Fraction of glycolide.

• Proceedings of the Korean Fiber Society Conference
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• 2000.04a
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• pp.241-244
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• 2000

• 대한미세수술학회:학술대회논문집
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• 1996.10a
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• pp.178-179
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• 1996

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.227.2-228
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• 2003

In many biodegradable polymers recently investigated, poly(lactic acid)(PLA) or poly(lactic-co-glycolic acid)(PLGA) have extensively been utilized as drug delivery systems for sustained release drug delivery. Recently, there has been increased interest in electrospinning, which can produce fibers that are sub-micron in diameter. This technique has been applied to various micro/nano fabrication areas using numerous polymers but very few uses in the sharmaceutical area have been reported. (omitted)

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• Polymer(Korea)
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• v.29 no.1
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• pp.69-73
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• 2005

To overcome the main disadvantages of non-viral gene delivery systems such as repeated administration due to the low transfection efficiency, poly(D,L-lactide-co-glycolide) was applied to encapsulate pDNA in its microsphere formulation. Free pDNA or various ratios (w/w) of chitosan/pDNA complexes was used for encapsulation, with the resulting encapsulation efficiency of 44%, 5%, and 8% for free pDNA, 0.7:1 and 1:1 ratios, respectively. Scanning electron micrographs of poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres encapsulating pDNA or chitosan-condensed pDNA revealed a smooth spherical shape immediately after microsphere preparation and a collapsed porous shape in 41 days due to the degradation of PLGA. In vitro release profile showed that the 0.7:1 (w/w) ratio formulation exerted 47% release in 26 days, whereas free pDNA or 1:1 (w/w) ratio formulation did only 15% or 32%, respectively.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.235-237
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• 2001

유전자 전달체에는 바이러스성 유전자 전달체와 비바이러스성 유전자 전달체의 두 종류가 있다. 바이러스성 유전자 전달체의 장점은 바이러스가 인체의 여러 세포에 침투가 용이하므로 유전자 전달의 효과가 크다는 것이다. 반면 바이러스에 의한 부작용과 인체의 면역 작용에 바이러스의 퇴치가 빠르게 진행되어 목적하는 효과가 반감된다는 단점이 있다. (중략)