• Macromolecular Research
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• 제11권5호
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• pp.352-356
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• 2003

The objectives of this study were to investigate the influence of gamma irradiation for sterilization on poly(D,L-lactide-co-glycolide) (PLGA) with different molecular weight and the effect of gamma irradiation on the release behavior of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine) from PLGA wafer with various irradiation doses. The effect of gamma irradiation on PLGA was evaluated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and electron paramagnetic resonance (EPR). The weight average molecular weight (M$_{w}$) and glass transition temperature (T$_{g}$) of PLGA decreased after gamma irradiation. The extent of M$_{w}$ reduction was dependent on irradiation dose and PLGA molecular weight. Using EPR spectroscopy, we successfully detected gamma irradiation induced free radicals in PLGA. The gamma irradiation increased the release rate of BCNU from PLGA wafer at applied irradiation doses except 2.5 Mrad of irradiation dose in this study.study.

• 방사선산업학회지
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• 제12권4호
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• pp.343-348
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• 2018

Preliminary study was perfomed to develop a biocompatible filter material using radiation energy. Electrosppined PLLA nano sheets were surface-modificated with hydrophilic groups(acrylic group) by using radiation. The physico-chemical and morphological characteristics of modified PLLA sheets were measured by ATR, SEM, contact angle, and hydrophilic (acryl group) introduction rate (TBO). As a result, there was no morphological(fiber structure) structure change due to radiation, and it was confirmed that an acrylic group was successfully introduced onto PLLA fiber sheet by radiation.

• Asian Pacific Journal of Cancer Prevention
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• 제15권12호
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• pp.4915-4918
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• 2014

Background and Aims: Advances in the treatment of cervical cancer over the last decade have predominantly involved the development of genes directed at molecular targets. Gene therapy is recognized to be a novel method for the treatment of cervical cancer. Genes can be administered into target cells via nanocarriers. This study aimed to develop systemically administrable nano-vectors. Floate (Fa) containing gene loaded nanoparticles (NPs) could target HeLa human cervical cancer cells through combination with receptors on the cells to increase the nuclear uptake of genetic materials. Methods: Fa was linked onto Poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PLA) to form Fa-PEG-PLA, and the resulting material was used to load plasmids of enhanced green fluorescence protein (pEGFP) to obtain gene loaded nanoparticles (Fa-NPs/DNA). Physical-chemical characteristics, in vitro release and cytotoxicity of Fa-NPs/DNA were evaluated. The in vitro transfection efficiency of Fa-NPs/DNA was evaluated in HeLa cells and human umbilical vein endothelial cells (HUVEC). PEG-PLA without Fa was used to load pEGFP from NPs/DNA as a control. Results: Fa-NPs/DNA has a particle size of 183 nm and a gene loading quantity of 92%. After 72h of transfection, Fa-NPs/DNA displayed over 20% higher transfection efficiency than NPs/DNA and 40% higher than naked DNA in HeLa cells. However, in HUVECs, no significant difference appeared between Fa-NPs/DNA and NPs/DNA. Conclusions: Fa-PEG-PLA NPs could function as excellent materials for gene loading. This nano-approach could be used as tumor cell targeted medicine for the treatment of cervical cancer.

• Journal of Pharmaceutical Investigation
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• 제36권2호
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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.

• 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.

• Journal of Pharmaceutical Investigation
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• 제34권5호
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• pp.369-377
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• 2004

The objective of this study was to investigate the patterns of protein leaching to an external phase during an ethyl acetate-based, double emulsion microencapsulation process. An aqueous protein solution (lactoglobulin, lysozyme, or ribonuclease; $W_1$) was emulsified in ethyl acetate containing poly-d,l-lactide-co-glycolide 75:25. The $W_1/O$ emulsion was transferred to a 0.5% polyvinyl alcohol solution saturated with ethyl acetate $(W_2)$. After the double emulsion was stirred for 5, 15, 30, or 45 min, additional 0.5% polyvinyl alcohol $(W_3)$ was quickly added into the emulsion. This so-called quenching step helped convert emulsion microdroplets into microspheres. After 2-hr stirring, microspheres were collected and dried. The degree of protein leaching to $W_2$ and/or $W_3$ phase was monitored during the microencapsulation process. In a separate, comparative experiment, the profile of protein leaching to an external phase was investigated during the conventional methylene chloride-based microencapsulation process. When ethyl acetate was used as a dispersed solvent, proteins continued diffusing to the $W_2$ phase, as stirring went on. Therefore, the timing of ethyl acetate quenching played an important role in determining the degree of protein microencapsulation efficiency. For example, when quenching was peformed after 5-min stirring of the primary $W_1/O$ emulsion, the encapsulation efficiencies of lactoglobulin and ribonuclease were $55.1{\pm}4.2\;and\;45.3{\pm}7.6%$, respectively. In contrast, when quenching was carried out in 45 min, their respective encapsulation efficiencies were $39.6{\pm}3.2\;and\;29.9{\pm}11.2%$. By sharp contrast, different results were attained with the methylene-chloride based process: up to 2 hr-stirring of the primary and double emulsions, less than 5% of a protein appeared in $W_2$. Afterwards, it started to partition from $W_1\;to\;W_2/W_3$, and such a tendency was affected by the amount of PLGA75:25 used to make microspheres. Different solvent properties (e.g., water miscibility) and their effect on microsphere hardening were to be held answerable for such marked differences observed with the two microencapsulation processes.

• 폴리머
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• 제25권6호
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• pp.893-901
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• 2001

조직공학적 신경재생 및 파킨슨씨병 등의 시경퇴행성 질환에서의 치료에 이용 목적으로 신경성장인자(nerve growth factor, NGF)를 생분해성 고분자 담체에 NGF를 서방화시키고자 PLA 담체에 함유시켜 유화동결건조법으로 제조하였다. 제조된 NGF의 방출량은 생체외 pH 7.4, 37$^{\circ}C$의 PBS 조건하에서 4주 동안 방출실험 하였으며, 함유된 NGF의 활성을 확인하기 위하여 PC-l2 세포에 직접 배양하여 확인하였다. 제조되어진 PLA 담체는 열린 셀 구조를 가졌으며, 초기 NGF의 함량이 많을수록 방출량도 증가를 보였으며, 제조과정에서의 NGF의 환성을 확인하기 위하여 PC-12 세포를 배양한 결과 신경돌기가 성장하였다. 본 연구는 생분해성 고분자 특정인 확산과 분해에 의해서 생물학적 활성물질인 NGF의 방출을 조절할 수 있으며, 조직공학적으로 서방화되어 3차원적인 신경재생을 가능케 할 것으로 기대된다.

• 폴리머
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• 제37권6호
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• pp.744-752
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• 2013

배향된 상태에서 복굴절이 없는 zero-${\Delta}$n 재료를 개발할 목적으로 용융혼합된 폴리락타이드(PLLA, (+)복굴절)/폴리(메틸 메타크릴레이트)(PMMA, (-)복굴절) 블렌드의 상용성과 PMMA의 공단량체인 메틸 아크릴레이트(MA)가 PLLA와의 상용성에 미치는 영향을 살펴보았다. MA 함량에 상관없이 모든 블렌드에서 조성에 따라 변하는 단일 $T_g$와 90% 이상의 투명도가 관찰되었으며, 이로부터 용융혼합된 PLLA/PMMA 블렌드는 분자수준에서 상용성을 보임을 확인하였다. 이들 블렌드는 $280^{\circ}C$의 온도에서도 안정한 단일상을 유지하였다. MA가 17 mol%첨가된 PMMA17과 PLLA의 블렌드의 경우 Hoffman-Weeks 방법을 적용하여 평형융점으로부터 구한 상호작용 에너지 밀도(B)는 $-0.74J/cm^3$이었다. PLLA/PMMA 블렌드는 배향되었을 때 조성고분자들의 고유 배향복굴절이 상쇄되어 특정 혼합비에서 "0" 가까운 복굴절 특성을 나타내었다. PLLA/PMMA5 블렌드의 경우 혼합비에 따른 복굴절 분산을 측정한 결과 zero-${\Delta}$n 특성을 보이는 혼합비에서 역분산이 나타나며, 파장의존성이 없는 복굴절 특성을 보이는 조성이 존재함을 확인하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권6호
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• pp.559-564
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• 2006

According to the development of operation technique and biologic materials, oromaxillofacial surgery department have used many kinds of metal and biologic materials in ORIF and plastic surgery. In maxillofacial fracture, ORIF with metal plate and screw have short healing period and good prognosis. But ORIF with metal materials have many complications as maxillofacial abnormal growth, screw loosening, bone malunion. And metal materials have not used in infection site. The purpose of this study is to evaluate the clinical value of 10 condylar fracture patients operated with absorbable screw at Wonkwang university. Ten patients(8 males, 2 female, mean aged 28) who had mandibular condyle process fracture treated with PLLA implants(poly-l-lactide) was recalled for follow-up clinical and radiologic examination for 10 years. Mouth opening recorvered to more than 35mm and occlusion was stable in all patients. All fractured mandibular condyles showed anatomic good reduction and long-term stability with the use of resorbable miniplates and screw. Bone healing was satisfactory in all patients, and there was no evidence of abnormal resorption of condylar process.

• Archives of Plastic Surgery
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• 제40권6호
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• pp.676-686
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• 2013

Background To overcome the potential drawbacks of a short half-life and dose-related adverse effects of using active transforming growth factor-beta 1 for cartilage engineering, a cell-mediated latent growth factor activation strategy was developed incorporating latent transforming growth factor-${\beta}$1 (LTGF) into an electrospun poly(L-lactide) scaffold. Methods The electrospun scaffold was surface modified with NH3 plasma and biofunctionalised with LTGF to produce both random and orientated biofunctionalised electrospun scaffolds. Scaffold surface chemical analysis and growth factor bioavailability assays were performed. In vitro biocompatibility and human nasal chondrocyte gene expression with these biofunctionalised electrospun scaffold templates were assessed. In vivo chondrogenic activity and chondrocyte gene expression were evaluated in athymic rats. Results Chemical analysis demonstrated that LTGF anchored to the scaffolds was available for enzymatic, chemical and cell activation. The biofunctionalised scaffolds were non-toxic. Gene expression suggested chondrocyte re-differentiation after 14 days in culture. By 6 weeks, the implanted biofunctionalised scaffolds had induced highly passaged chondrocytes to re-express Col2A1 and produce type II collagen. Conclusions We have demonstrated a proof of concept for cell-mediated activation of anchored growth factors using a novel biofunctionalised scaffold in cartilage engineering. This presents a platform for development of protein delivery systems and for tissue engineering.