• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.100-109
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• 2015

Environmental problems from petroleum-based plastic wastes have been rapidly increasing in recent years. The alternative solution is focus on the development of environmental friendly plastic derived from renewable resource. Poly(lactic acid) (PLA) is a biodegradable polymer synthesized from biomass having potential to replace the petroleum-based non-degradable polymers utilizations. PLA can be synthesized by two methods: (1) ring-opening of lactide intermediate and (2) direct polycondensation of lactic acid processes. The latter process has advantages on high yields and high purity of polymer products, materials handling and ease of process treatments. The polymerization process of PLA synthesis has been widely studied in a laboratory scale. However, the mass scale production using direct polycondensation of lactic acid has not been reported. We have investigated the kinetics and scale-up process of direct polycondensation method to produce PLA in a pilot scale. The order of reaction is 2 and activation energy of lactic acid to lactic acid oligomers is 61.58 kJ/mol. The pre-polymer was further polymerized in a solid state polymerization (SSP) process. The synthesized PLA from both the laboratory and pilot scales show the comparable properties such as melting temperature and molecular weight. The appearance of synthesized PLA is yellow-white solid powder.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권4호
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• pp.325-331
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• 1999

We tested the bone regenerating capacity and histologic response of bioresorbable matrix-type implant, which was made with Poly(lactide-co-glycolide)(PLGA) and bone apatite for the carrier of bone morphogenetic protein(BMP). The critical size defect of 8mm in diameter was created at the calvaria of SD rats(n=18), and repaired with polymer implant with $15{\mu}g$ of rhBMP-2(n=9) or without it(n=9). At 2 weeks, 1 months after implantation, the animals were sacrificed(3 animals at every interval and group) and histologically evaluated. The calvarial defect which was repaired with polymer with BMP healed with newly formed bone about 70% of total defect. But that without BMP showed only 0 to under 30% bony healing. Inflammatory response was absent in both group through the experimental period, but there's marked foreign body giant response though it was a little less significant in polymer with BMP group. As the polymer was resorbed, the space was infiltrated and replaced by fibrovascular tissue, not by bone. In conclusion, our formulation of bioresorbable matrix implant loaded with bone morphogenetic protein works good as a bone regenerating material. However, it is mandatory to devise our system to have better osteoinductive and osteoconductive property, and less multinucleated giant cell response.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권5호
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• pp.499-503
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• 2007

Introduction: In orthognathic surgery, internal fixation has been usually done with titanium plates and screws. Recently, Biodegradable plates and screws have been frequently used but the reports of long term results of postoperative stability are rare, especially after maxillary reposition in orthognathic surgery. Objective: In order to clarify the clinical utility of self-reinforced bioresorbable poly-70L/30DL-Lactide miniplates & screws in maxillary fixation after LeFort I osteotomy, this study examined the postsurgical changes in maxilla and complications of biodegradable plates and screws. Study design: Nineteen patients who had undergone maxillary internal fixation using biodegradable plates and screws were evaluated radiographically and clinically. A comparison study of the changes in maxilla position after surgery in all 19 patients was performed with 1-week, 1-month, 3-months, 6-months and/or 1-year postoperative lateral cephalograms by tracing. Complication of the biodegradable plates and screws was evaluated by follow-up roentgenograms and clinical observation. And one-way ANOVA test was used for statistical analysis. Results: The position of the maxillary bone was stable after surgery and was not changed significantly from 1 week to 1 year after operation. And we could not find any complication of biodegradable plates and screws. Conclusions: Internal fixation of the maxilla after LeFort I osteotomy using self-reinforced biodegradable plates and screws is a reliable method for maintaining postoperative position of the maxilla after LeFort I osteotomy.

• 폴리머
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• 제33권4호
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• pp.353-357
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• 2009

분무건조는 약물의 입자 제조에 널리 사용되고 있는 효과적이고 안정적인 공정 중 하나이다. 과거 분무건조의 방법에서는 입자의 응집을 조절하기 쉽지 않았으며, 크기 조절에도 많은 어려움을 겪어 왔다. 특히 고분자 입자의 제조는 저분자 유기물질인 식품, 의약원료 등과 비교하여 상대적으로 제조하기 어려운 면이 있었다. 본 연구에서는 기존의 분무건조기를 개조하여 노즐에 전기장을 외부에서 가해 줌과 동시에 동축 이중 노즐을 사용하여 고분자 입자의 제조를 시도하였다. 내부 고분자 물질로는 폴리에틸렌글리콜과 폴리락타이드코글리코라이드를, 외부 물질로는 락토오스를 사용하였다. 그 결과 전기장을 사용하지 않는 분무건조에 비해 비교적 일정한 크기와 모양을 제조할 수 있었으며, 입자 간의 응집을 줄일 수 있음을 확인하였다. 전기분무건조된 PLGA 분말은 주로 $2{\sim}5{\mu}m$ 기인 둥근 모양의 입자로 구성되었다.

• 멤브레인
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• 제15권1호
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• pp.8-14
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• 2005

생체 적합성이 우수한 히아루론산과 생분해성이 우수한 폴리 락타이드의 모노머를 결합하여 인체내에서 분해속도를 조절할 수 있는 생체적합성이 우수한 생체 재료를 제조하고자 하였다. 냉동 건조법을 이용하여 히아루론산과 폴리락타이드의 모노머인 젖산 또는 이량체인 락타이드를 가교제 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide로 가교시켰다. 생성된 막을 적외선 흡수 분광법으로 분석한 결과 에스테르 결합이 생성됨을 확인하였고, 핵자기 공명 분광법으로 분석하여 이 에스테르 결합이 젖산의 반응 참여에 의한 것임을 확인하였다. 젖산과 히아루론산의 몰비를 1부터 10까지 증가시키면서 가교시킨 결과 젖산의 전화율(6∼32%)과 가교도(4∼l9%)는 증가하였으나, 반응에 참여한 젖산이 가교되는 선택도는 몰비에 관계없이 62% 정도로 일정하였다. 몰비가 커서 젖산이 많이 첨가되면 취성은 강해졌으나 생분해 속도는 빨라졌으며, 팽윤도는 500에서 2000% 범위의 값을 보였다.

• 한국재료학회지
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• 제16권11호
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• pp.676-680
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• 2006

The biodegradable $\beta$-tricalcium phosphate ($\beta$-TCP)/poly(lactide-co-glycolide) (PLGA) composites were synthesized by in situ polymerization with microwave energy. The degradation behavior of $\beta$-TCP/PLGA composite was investigated by soaking in simulated body fluid (SBF) for 4 weeks. The molecular weight of the $\beta$-TCP/PLGA composites decreased with soaking time until week 2, whereas the loss rate of molecular weight reduced after week 2. The incubation time was needed for the degradation of the $\beta$-TCP, indicating that the $\beta$-TCP should be detached from the PLGA matrix and then degraded into SBF solution. The studies of mass loss of the composites with the soaking time revealed that the degradation behavior of PLGA would be processed with the transformation from the polymer to the oligomer followed by the degradation. Morphological changes, whisker-like, due to transformation and degradation of polymer in the composites were observed after week 2. On the basis of the results, it found that the degradation behavior of $\beta$-TCP/PLGA composites was influenced by the $\beta$-TCP content in the composites and the degradation rate of the composites could be controlled by the initial molecular weight of PLGA in the composites.

• 대한의용생체공학회:의공학회지
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• 제27권5호
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• pp.218-223
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• 2006

We examined the effects of ${\beta}$-glucan-reinforced PLGA film and scaffold on HDFs (human dermal fibroblast) attachment and proliferation. The PLGA films were prepared by simple solvent-casting method. The prepared films were grafted with $(1{\to}3)(1{\to}6)-{\beta}-glucan$ in various ratios after plasma treatment on surface. The surface of the film was characterized by contact angle measurement, scanning electron microscope (SEM), and Fourier-transform infrared spectrophotometer (FT-IR). The amount of $(1{\to}3)(1{\to}6)-{\beta}-glucan$ in the prepared film was indirectly determined by phenol-sulfuric acid method. The HDFs (Human dermal fibroblasts) were used to evaluate the cell attachment and proliferation on PLGA specimens before and after plasma/${\beta}-glucan$ treatment. The result showed that the plasma treated groups exhibited more mont of ${\beta}-glucan$ might be grafted than the non plasma treated groups. Cell attachment was significantly enhanced in the plasma/${\beta}-glucan$ grafted group after 4 hours incubation (p<0.05) due to the improved hydrophilicity and cytoactivity effect of the ${\beta}-glucan$. The cell proliferation of plasma/${\beta}-glucan$ (2mg/ml) grafted group was the highest rate among the groups (p<0.05).

• 한국산업보건학회지
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• 제32권2호
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• pp.153-162
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• 2022

Objectives: Fused deposition modeling (FDM) 3D printer which is one of the material extrusion (MEX) technologies is an additive manufacturing (AM) process. 3D printers have been distributed widely in Korea, particularly in school and office, even at home. Several studies have shown that nanoparticles and volatile organic compounds (VOCs) were emitted from an FDM 3D printing process. The objective of this study was to identify types of chemicals possibly emitted from FDM 3D printing materials such as PLA (polylactic acid), ABS (acrylonitrile butadiene styrene), nylon, PETG (polyethylene terephthalate glycol), PVA (polyvinyl alcohol), PC (polycarbonate) filaments. Methods: 19 FDM 3D printing filaments which have been distributed in Korea were selected and analyzed VOCs emitted of 3D printing materials by headspace gas chromatography mass spectrometry (headspace GC-MS). Subsamples were put into a vial and heated up to 200℃ (500 rpm) during 20 minutes before analyzing FDM 3D printing filaments. Results: In the case of PLA filament, lactide and methyl methacrylate, the monomer components of one, were detected, and the volume ratio ranged 27~93%, 0.5~37% respectively. In the case of ABS filaments, styrene (50.5~59.1%), the monomer components of one, was detected. Several VOCs among acetaldehyde, toluene, ethylbenzene, xylene, etc were detected from each FDM 3D printing filaments. Conclusions: Several VOCs, semi-VOCs were emitted from FDM 3D printing filaments in this study and previous studies. Users were possibly exposed to ones so that we strongly believe that we recommend to install the ventilation system such as a local exhaust ventilation (LEV) when they operate the FDM 3D printers in a workplace.

• 대한치과보철학회지
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• 제54권2호
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• pp.120-125
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• 2016

목적: 본 연구는 in-vitro 상에서 recombinant human transforming growth factor-beta (rhTGF-${\beta}2$)와 poly(D,L-lactide-co-glycolide) (PLGA) 의 복합체를 티타늄 디스크 표면에 코팅하여, 생물학적으로 간엽줄기세포 증식에 미치는 영향을 조사하기 위해 시행되었다. 재료 및 방법: 양극산화 디스크에 일렉트로스프레이 코팅법을 이용하여 anodized 된 티타늄 디스크를 대조군으로 설정하고, rhTGF-${\beta}2$를 125 ng/ml와 500 ng/ml 농도로 코팅한 것을 실험군으로 하였다. 티타늄 디스크 표면에 분사된 복합체가 균일하게 분사되었는지 field-emission scanning electron microscopy (FE-SEM)을 통해 확인하였으며, atomic force microscope (AFM) test를 이용하여 rhTGF-${\beta}2$로 코팅한 디스크와 양극산화 디스크의 거칠기 차이를 확인하였다. 디스크 위에 간엽줄기세포 배양 후 1, 4, 7일에 세포증식 양상을 MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl-tetrazolium bromide) assay 검사를 통해 확인하였다. 결과: AFM 결과 대조군과 실험군에서 거칠기의 유의할만한 차이가 없었다 (P>.05). MTT 결과 7일차 배양 결과에서 125 ng/ml와 500 ng/ml PLGA/TGF-${\beta}2$처리된 그룹은 각각 평균 0.45와 0.48이였으며, 대조군은 평균 0.33으로 PLGA/TGF-${\beta}2$처리된 그룹에서 세포 증식이 더 활성화 되는 것을 확인할 수 있었다 (P<.05). 결론: rhTGF-${\beta}2$ 복합체를 electrospray법으로 코팅한 티타늄 표면에서 7일차에서 줄기간엽세포의 빠른 증식을 확인하였다. 또한 복합체 처리군의 농도가 증가할수록 높은 세포 성장 수치를 보였다.

• 폴리머
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• 제29권6호
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• pp.543-548
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• 2005

이중층 미립구는 단일층 미립구에 비해서 낮은 초기 방출량과 국소 지항성, 및 약물 방출량 제어 등의 장점 을 갖고 있다. 그러나 포접 방식이 까다롭고 2단계 이상의 제조 과정이 필요하며 특히 미립구 제조 시 크기 조절이 어렵다는 단점을 갖고 있다. 따라서 본 연구에서는 락타이드글리콜라이드 공중합체(PLGA)와 덱스트란의 서로 다른 고분자를 초고주파 분쇄 유무에 따른 수중유형(O/W) 용매 증발법을 이용하여 이중층 미립구를 제조하였다. 또한 PLGA의 농도에 따라 미립구 크기의 변화를 연구하였다. 이중층 미립구는 전자주사현미경, 동초점 형광 레이저현미경(CFLM), 캠스코프를 이용하여 조사하였다. 제조된 이중층 미립구의 외부층이 매끄러운 구형의 형태를 나타냄을 확인할 수 있었으며, 절단시 내부층과 외부층의 형태를 확실히 구분할 수 있었다. 이에 외부층과 내부층의 구성 물질을 확인하고자 플루오르신-5-이소시아네이트-덱스트란(FITC-덱스트란)을 이용해 CFLM을 관찰한 결과 형광을 띠는 덱스트란으로 구성된 내부층과 형광을 띠지 않는 PLGA 외부층을 관찰하였다. 또한 PLGA의 함량에 따른 미립구의 크기는 전체적으로 증가하는 경향을 확인하였다. 이와 같은 결과로부터 비교적 간단한 수중유형 용매 증발법을 이용하여 PLGA와 덱스트란의 이중층 미립구의 제조가 가능함을 확인할 수 있었다.