• Journal of Periodontal and Implant Science
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• 제27권3호
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• pp.633-645
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• 1997

The recent trend of research and development on guided tissue regeneration focuses on the biodegradable membranes, which eliminate the need for subsequent surgical removal. They have demonstrated significant and equivalent clinical improvements to the ePTFE membranes. This study evaluate guided tissue regeneration wound healing in surgically induced intrabony periodontal defects following surgical treatment with a synthetic biodegradable membranes, made from a copolymer of glycolide and lactide, in 8 beagle dogs. After full thickeness flap reflection, exposed buccal bone of maxillary and mandibular canine and premolar was removed surgically mesiodistally and occlusoapically at $6mm{\times}6mm$ in size for preparation of periodontal defects. In experimental sites a customized barrier was formed and fitted to cover the defect. Flap was replaced slightly coronal to CEJ and sutured. Plaque control program was initiated and maintained until completion of the study. In 4, 8, 16 and 24 weeks after surgery, the animals were sacrificed and then undecalcified specimens were prepared for histologic evaluation. Histologic examination indicated significant periodontal regeneration characterized by new connective tissue attachment, cementum formation and bone formation. These membranes showed good biocompatibility throughout experiodontal period. The barriers had been completely resorbed with no apparent adverse effect on periodontal wound healing at 24 weeks. These results implicated that present synthetic biodegradable membrane facilitated guided tissue regeneration in periodontal defect.

• Journal of Periodontal and Implant Science
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• 제31권2호
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• pp.299-315
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• 2001

Application of membranes for guided tissue regeneration(GTR) have been confined to the subgingival barrier functions; however, many studies have provided evidence that some drugs, including tetracycline, initially can promote the growth of periodontal ligament or alveolar bone in peridontal therapy. Osseous regeneration in periodontal defects is increased by local administration of tetracycline due to its anti-collagenolytic effect, which enhances bone-forming ability via osteoblast cell chemotaxis and reduced bone resorption. The aim of this study was to evaluate effects of tetracycline loaded poly-L-lactide(PLLA) barrier membranes for guided bone regenerative potential. Tetracycline was incorporated into the PLLA membrane with the ratio 10% to PLLA by weight. Ability to guided bone regeneration of the membranes were tested by measuring new bone in the tibial defects($7{\times}10{\times}5\;mm^3$) of the beagle dog for 4,5, and 6 weeks. In control, drug-unloaded PLLA membranes were used in same size of defect. In histologic finding of the defect area, a few inflammatory cells were observed in both groups. These membrane were not perforated by connective tissue and maintained their mechanical integrity for the barrier function for 4-6 weeks. New bone formation was greater in defects covered by tetracycline-loaded membrane than in defects covered by drug- unloaded membranes. In bone regeneration guiding potential test, tetracycline-loaded membrane was more effective than drug- unloaded membranes(p<0.05). These results suggest that tetracycline-loaded PLLA membranes potentially enhance guided bone regenerative efficacy and might be a useful barrier for GTR in periodontal treatment.

• 폴리머
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• 제28권4호
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• pp.335-343
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• 2004

카뮤스틴 (1,3-bis(2-chloroethy1-nitrosourea, BICNU)은 뇌종양 치료를 위하여 임상적으로 사용되는 약물로 짧은 생물학적 반감기를 가지고 있어 장기방출에 적합하지 않다. 하지만, poly(D,L-lactide-co-glycolide) (PLGA)는 벌크 분해 특성으로 인해 약물의 장기방출에 유용하며, PLGA의 유도체인 글리콜라이드 단량체는 독성이 없고 PLGA와 유사한 생분해성을 가지고 있어 BICNU의 방출조절에 이용된다. 이 실험에서 BICNU를 함유한 PLGA 웨이퍼는 일반적인 직접압축법에 의해 제조한 후 BICNU의 방출거동과 웨이펴의 분해속도를 전자주사현미경, 핵자기공명장치 그리고 젤투과크로마토그래피를 통해 관찰하였다. 또한, 글리콜라이드 단량체의 함량변화에 따른 다중층 웨이퍼를 제조하여 단일층 웨이퍼와의 방출거동을 비교하였다. 이러한 결과들로부터 BICNU를 함유한 PLGA 웨이퍼의 약물방출은 BICNU와 글리콜라이드 단량체의 함량이 증가할수록 증가하였고, 다중층 웨이퍼에서 외부층의 글리콜라이드 단량체와 BICNU가 약물방출 거동과 분해속도에 영향을 미친다는 것을 확인하였다.

• 폴리머
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• 제29권1호
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• pp.69-73
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• 2005

비바이러스성 유전자 전달체의 주요 단점인 낮은 transfection 효율에 기인한 반복투여 등을 극복하기 위하여 poly (D,L-lactide-co-glycolide)를 이용하여 DNA가 봉입된 미립구를 제조하였다. pDNA 그 자체 또는 여러 비율의 키토산/pDNA 복합체를 사용하여 봉입하였고, 그 결과 44%(pDNA 그 자체), 5%(0.7:1 미토산/pDNA 복합체), 그리고 8%(1:1 키토산/pDNA 복합체)의 봉입효율을 나타내었다. 주사전자현미경(SEM)을 통해 본 표면구조에서는 미립구 제조 직후에서는 매우 매끈한 구형을 보이다가 제조 후 41일 경에는 찌그러진 다공성의 구조를 보였는데 이는 미립구 제조에 사용한 poly(D,L-lactic-co-glycolic acid)(PLGA) 고분자의 분해에 의한 것으로 생각된다. 시험관내 방출실험에서는 0.7:1 키토산/pDNA 복합체를 사용한 미립구에서 47%의 pDNA가 26일만에 방출된데 반해, pDNA 그 자체 혹은 1:1 키토산/pDNA 복합체를 사용한 미립구에서는 각각 15% 혹은 32%의 pDNA 방출을 나타내었다.

• 폴리머
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• 제26권5호
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• pp.680-690
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• 2002

골 재흡수 치료를 목적으로 파미드로네이트를 지속적으로 방출하는 제형으로 제조하기 위하여 락타이드-글리콜라이드 공중합체 (PLGA, 락타이드 : 글리콜라이드 몰비 = 75 : 25, 분자량 20000 g/mole 및 90000 g/mole)를 이용하여 직접압축 성형방법으로 생분해성 웨이퍼를 제조하였다. 약물과 고분자의 함량비 웨이퍼의 두께, PLGA 분자량 등을 조절하여 PLGA 웨이퍼를 제조하였고 이들의 형태학적 특성과 방출거동 및 분해거동을 살펴보았다. 웨이퍼의 제조는 혼합된 분말을 웨이퍼 제작용 몰드에 넣은 후 프레스를 이용하여 일정 압력으로 일정시간 동안 상온에서 가압하여 제조하였다. 제조된 웨이퍼는 약물의 초기함량이 증가할수록 방출속도가 빠르게 나타났으며, 제형의 두께가 두꺼워질수록 시간이 경과함에 따라 약물의 방출속도가 증가하였다. 또한 고분자의 분자량이 큰 것이 작은 것에 비해 상대적으로 초기 약물 방출량이 적고 방출되는 속도 또한 느려져. 저분자보다 오랫동안 약물이 방출되었다. 이러한 약물전달 시스템은 압축성형방법에 의해 제조하므로 제조가 간단하고 약물방출속도를 정확하게 제어할 수 있으므로 이식을 위한 제형으로 제조시 유용하게 쓰일 것으로 예상되었다.

• Macromolecular Research
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• 제16권2호
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• pp.139-148
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• 2008

Biodegradable and elastic poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using $^{60}Co-{\gamma}$ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the firms. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of thc PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < $32^{\circ}C$, and abrupt collapse when the temperature was increased to $40^{\circ}C$. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at $40^{\circ}C$ relative to that at $25^{\circ}C$. This approach of the temperature-controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

• 방사선산업학회지
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• 제9권4호
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• pp.171-180
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• 2015

Vascular tissue engineering has been accessed to mimic the natural composition of the blood vessel containing intima, media, and adventitia layers. We fabricated mechanically expanded PLLA/PLCL nanofibers using electrospinning and UTM. The pore size of the meshes was increased the gelatin immobilized AAc-PLLA/PLCL nanofibers ($203.30{\pm}49.62microns$) than PLLA/PLCL nanofibers ($59.99{\pm}8.66microns$) after mechanical expansion. To increase the cell adhesion and proliferation, we introduced carboxyl group, and gelatin was conjugated on them. The properties of the PLLA/PLCL nanofibers were analyzed with SEM, ATR-FTIR, TBO staining, and water contact angle measurement, general cell responses on the PLLA/PLCL nanofibers such as adhesion, proliferation, and infiltration were also investigated using smooth muscle cell (SMC). During the SMC culture, the initial viability of the cells was significantly increased on the gelatin immobilized AAc-PLLA/PLCL nanofibers, and infiltration of the cells was also enhanced on them. Therefore, gelatin immobilized AAc-PLLA/PLCL nanofibers and mechanically expanded meshes may be a good tool for vascular tissue engineering application.

• 방사선산업학회지
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• 제7권1호
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.

• Composites Research
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• 제31권6호
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• pp.371-378
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• 2018

본 연구에서는 폴리유산 나노복합재의 열탄성 거동을 예측하기 위해 분자동역학 전산모사를 수행하고 그 결과를 열탄성 미시역학 모델 예측해와 비교하였다. 폴리유산의 두 이성질체인 D유산(Poly D-lactide)와 L유산(Poly L-lactide)을 혼합한 스테레오 콤플렉스를 모델링하였고 이들을 기지로 사용한 탄소나노튜브 나노복합재를 구성하였다. 유산의 분해 유무에 따른 유리전이온도와 탄성계수 그리고 열팽창계수를 앙상블 전산모사를 통해 예측하였다. 미시역학 모델에서는 계면의 완전 결합을 가정한 이중입자 모델을 적용하여 탄성계수와 열팽창계수를 동일한 조성에서 예측하였다. 그 결과 열적 안정성에 있어 스테레오 콤플렉스에 탄소나노튜브가 첨가될 경우 유산의 뛰어난 계면 흡착과 이에 따른 열적 안정성 향상을 보였다. 순수한 유산과 나노복합재 모두 가수 분해에 따른 열적 특성 변화는 관찰되지 않았다. 또한, 스테레오 콤플렉스와 나노튜브 간 계면은 약한 불완전 결합상태 임을 알 수 있었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.644-647
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• 2003

Materials currently used as an injectable bulking agent in the dermatologic and urologic fields revealed several drawbacks such as particles migration, inflammatory reaction, allergic reaction, rapid volume shrinkage, and necessity of a donor site. In this study, we have developed injectable biomaterial comprising poly (DL- lactide-co-glycolide)(PLGA) and hyaluronic acid gel to overcome these problems. PLGA is a biocompatible synthetic material and hyaluronic acid is a common substance found in living organisms. We examined the feasibility of injection through needle and tested biocompatibility in animal model. After transplantation, injected sites and distant organs were examined histologically to verify a new tissue formation, inflammation, and particles migrations. Injected volume was maintained approximately 80 percent for 2 months. Results demonstrated that the developed material was injectable through various gauges of needles and induced a new bulking tissue formation without serious inflammatory reaction.