• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.370-371
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• 2003

Poly(lactic acid) is a thermoplastic and biodegradable polymer[1-3]. It has a wide range of application in medical fields such as sutures, screws for bone fractures and drug delivery systems. It has additional potential in other fields like agriculture and packaging. In recent years, there has been an increased interest in star-shaped polymers because they have a higher segment density within the distance of its radius of rotation than linear polymers have under the same conditions.[4] (omitted)

• Macromolecular Research
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• 제10권2호
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• pp.54-59
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• 2002

ABA triblock copolymers of L-lactide and trimethylene carbonate with several different compositions were prepared by sequential ring-opening polymerization in the presence of diethylene glycol. Also chain-extension reactions of the resulting copolymers were carried out using hexamethylene diisocyanate to produce relatively high molecular weight polymers, which could be cast into elastomeric tough films. The polymers with certain L-lactide contents were partially crystalline, exhibiting two-phase morphology. The polymer films showed reversible elastic behavior under tensile tension, providing a novel thermoplastic elastomer possessing desirable properties such as biodegradability and good mechanical properties.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.379-380
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• 2002

기계적 성질이 우수한 PVC와 생분해성이 우수한 고분자로 알려져 있는 폴리카프로락톤 (PCL)과 블렌드하여 새로운 소재의 생분해성 필름을 제조하여 생분해성 효과에 대해 조사하였으며, 그 결과 PCL/PVC 필름의 표면은 8주 후에 다수의 작은 구멍이 형성되었으며, 이러한 결과는 PCL의 함량이 9%로 낮아도 생분해성을 지닌다는 것을 의미한다.

• 한국응용과학기술학회지
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• 제20권4호
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• pp.324-331
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• 2003

Particulate leaching method for the preparation of porous PLLA scaffolds was carried out and especially, the effect of PLLA/$CHCl_3$ solution concentration on the salt leaching rate and the pore structure of PLLA scaffolds were considered. It was found that maintaining lower PLLA/$CHCl_3$ concentration and higher $CHCl_3$ evaporation temperature in the preparation of PLLA/NaCl mixtures resulted in the enhancement of salt leaching rat e and higher porosity. This is understood that those conditions could minimize the formation of dense PLLA layer on the surface of PLLA/NaCl mixture as well as introducing better porosity on the surface. Higher salt leaching temperature accelerated the salt leaching rate but it seems that there is no influence on the porosity of PLLA scaffolds.

• BMB Reports
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• 제49권1호
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• pp.26-36
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• 2016

Emerging trends for cardiac tissue engineering are focused on increasing the biocompatibility and tissue regeneration ability of artificial heart tissue by incorporating various cell sources and bioactive molecules. Although primary cardiomyocytes can be successfully implanted, clinical applications are restricted due to their low survival rates and poor proliferation. To develop successful cardiovascular tissue regeneration systems, new technologies must be introduced to improve myocardial regeneration. Electrospinning is a simple, versatile technique for fabricating nanofibers. Here, we discuss various biodegradable polymers (natural, synthetic, and combinatorial polymers) that can be used for fiber fabrication. We also describe a series of fiber modification methods that can increase cell survival, proliferation, and migration and provide supporting mechanical properties by mimicking micro-environment structures, such as the extracellular matrix (ECM). In addition, the applications and types of nanofiber-based scaffolds for myocardial regeneration are described. Finally, fusion research methods combined with stem cells and scaffolds to improve biocompatibility are discussed. [BMB Reports 2016; 49(1): 26-36]

• Advances in materials Research
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• 제4권4호
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• pp.207-214
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• 2015

It has been reported in the technical literature that orotic acid can be used in order to induce improved crystallization of biodegradable and biocompatible polymers like poly(L-lactic acid), polyhydroxybutyrate and poly(hydroxybutyrate-co-hydroxyhexaonat). The expected advantage of the changed crystalline structure is a reinforcing effect of the polymers. A lot of papers reported about the application of inorganic and organic agents for acceleration of heterogeneous nucleation. This study reports on an attempt to use orotic acid as appropriate non-toxic nucleating agent for improving mechanical properties of isotactic polypropylene. Special attention is given to demonstrate the effect of nucleation in a typical melt spinning process in order to improve the mechanical properties. The effects were demonstrated using rheology, thermal analysis and tensile testing.

• Macromolecular Research
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• 제10권6호
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• pp.359-364
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• 2002

A series of PLA-PEO-PLA triblock stereo-copolymers with varying PLA/PEO and L-DL-LA ratios were synthesized via ring opening pelymerizations. Aqueous solutions of these copolymers undergo thermo-responsive phase transitions as the temperature monotonically increases. Further study shows that there is a critical gel concentration (CGC), and also lower and upper critical gel temperatures (CGTs), at which the thermo-responsive phase transition occurs. The CGC and CGTs are affected by various factors such as block length, as well as the compositions of the PLA blocks and of the additives. In particular, the changes in the phase diagram produced by varying the L-/DL-LA ratio in the PLA blocks were determined to be mainly due to consequent stereo-regularity changes in the PLA blocks.

• Journal of Microbiology
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• 제45권2호
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• pp.87-97
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• 2007

Medium-chain-length polyhydroxyalkanoates (MCL-PHAs), which have constituents with a typical chain length of $C_{6}-C_{14}$, are polyesters that are synthesized and accumulated in a wide variety of Gram-negative bacteria, mainly pseudomonads. These biopolyesters are promising materials for various applications because they have useful mechanical properties and are biodegradable and biocompatible. The versatile metabolic capacity of some Pseudomonas spp. enables them to synthesize MCL-PHAs that contain various functional substituents; these MCL-PHAs are of great interest because these functional groups can improve the physical properties of the polymers, allowing the creation of tailor-made products. Moreover, some functional substituents can be modified by chemical reactions to obtain more useful groups that can extend the potential applications of MCL-PHAs as environmentally friendly polymers and functional biomaterials for use in biomedical fields. Although MCL-PHAs are water-insoluble, hydrophobic polymers, they can be degraded by microorganisms that produce extracellular MCL-PHA depolymerase. MCL-PHA-degraders are relatively uncommon in natural environments and, to date, only a limited number of MCL-PHA depolymerases have been investigated at the molecular level. All known MCL-PHA depolymerases share a highly significant similarity in amino acid sequences, as well as several enzymatic characteristics. This paper reviews recent advances in our knowledge of MCL-PHAs, with particular emphasis on the findings by our research group.

• 폴리머
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• 제29권5호
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• pp.518-521
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• 2005

생분해성 고분자와 수화젤의 약물 전달 시스템과 조직 공학을 포함하는 다양한 생의학적인 응용이 점차 확대되고 있다. 하이드록실 pendant group을 갖고 있는 폴리아미노산의 하나인 PHEA는 뛰어난 생분해성과 우수한 생체적합성을 갖는 고분자로 알려져 있다 PHEA 및 그 유도고분자를 제조하고 이를 다양한 생의학적인 응용에 적용하는 연구가 진행되어 왔다. 본 연구에서는 유기용매에서 가교제인 HMDI를 사용하여 PHEA 수화젤을 제조하였다. PHEA는 아스팔트산의 열 축중합에 의해 합성한 polysuccinimide와 ethanolamine과의 고분자 반응으로부터 제조하였다. 제조한 수화젤에 대한 서로 다른 수용액과 pH용액에서의 팽윤 거동을 조사하였고, SEM을 통한 수화젤의 모폴로지와 가수분해 거동을 관찰하였다.

• 폴리머
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• 제26권5호
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• pp.670-679
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• 2002

1, 3-bis[2-chloroethyl]-1-nitrosourea (BCNU, carmustine)는 악성 뇌종양 치료를 위하여 화학요법적 임상에서 널리 사용되는 약물이다. 또한, poly(D,L-lactide-co-glycolide) (PLGA, 분자량: 20000 g/mole, 락타이드와 글리콜라이드 몰비 75 : 25)는 약물전달시스템을 위한 약물 전달체로써 사용되어지는 잘 알려진 생분해성 초분자이다. 본 연구에서 폴리비닐피롤리돈 (PVP) 또는 폴리에틸렌옥사이드 (PEO)를 함유하고 있는 BCNU 함유 PLGA 웨이퍼들의 BCNU 방출거동과 웨이퍼에 포접된 친수성 고분자의 효과를 조사하였다. 친수성 고분자의 첨가 또는 첨가 없이 BCNU 함유 PLGA 미분말은 분사건조법에 의해 제조하였으며, 제조된 BCNU 함유 PLGA 미분말은 압축성 형법에 의해 웨이퍼형태고 제조하였다. 친수성 고분자가 첨가된 BCNU 함유 PLGA 미분말의 포접율은 85∼97%였고, PLGA에 포접된 BCNU의 결정성은 현저히 감소하였다. 약물 방출 경향과 분해 거동에서 친수성 고분자의 함량이 증가할수록 BCNU의 초기방출량과 방출속도는 증가됨을 확인하였다. 방출시험 기간동안 웨이퍼의 형태변화와 무게변화를 측정함으로써 친수성 고분자의 함량이 증가할수록 PLGA의 수차와 분해가 촉진됨을 관찰하였다.