• Polymer(Korea)
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• v.35 no.6
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• pp.499-504
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• 2011

Articular cartilage has an intrinsic difficulty in recovering damages, which requires its tissue engineering treatment. Demineralized bone particle (DBP) contains various bioactive molecules. It is widely used biomaterials in the field of tissue engineering. We developed the synthetic/natural hybrid scaffolds with poly(lactide-co-glycolide) (PLGA) and solution of DBP. The chondrocytes were seeded on the PLGA-DBP scaffolds and MTT assay, morphological observation, biological assay for collagen, sGAG, and RT-PCR were performed to analyze the effect of the DBP on cell viability and extracellular matrix secretion. In SEM observation, we observed that PLGA-DBP scaffolds had uniform porosity. As MTT assay showed scaffolds containing DB solution had higher cell viability then only PLGA scaffolds. The PLGA-DBP scaffolds had better ECM production than PLGA scaffold. It was proven by the higher specific mRNA expression in the PLGA-DBP scaffold than that in PLGA scaffold. These results indicated that PLGA-DBP scaffolds might serve as potential cell delivery vehicles and structural bases for in vitro tissue engineered articular cartilage.

• Polymer(Korea)
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• v.32 no.5
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• pp.403-408
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• 2008

Keratin is the major structural fibrous protein providing outer covering such as wool, hair, and nail. Keratin is useful as natural protein. We developed the keratin loaded poly(L-lactide-co-glycolide) (PLGA) scaffolds (keratin/PLGA) for the possibility of the application of the tissue engineering using bone marrow mesenchymal (BMSCs). Keratin/PLGA (contents 0%, 10%, 20% and 50% of PLGA weight) scaffolds were prepared by solvent casting/salt leaching method. We characterized porosity, wettability, and water uptake ability, DSC of keratin/PLGA scaffold. We seeded BMSCs isolated from the femurs of rat into the inner core of the hybrid scaffold. Celluar viability were assayed by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl-tetrazolium bromide (MTT) test. We confirmed that keratin/PLGA scaffold is hydrophilic by wettability, and water uptake ability measurement results. In MTT assay results, cell viability in scaffolds impregnated 10 and 20 wt% of keratin were higher than other scaffolds. In conclusion, we suggest that keratin/PLGA scaffold may be useful to tissue engineering using BMSCs.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3225-3232
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• 2012

The purposes of this research were to synthesize amoxicillin-carrying magnetic nanoparticles. Magnetic nanoparticles were prepared by a chemical precipitation of ferric and ferrous chloride salts in the presence of a strong basic solution. PLGA and PLGA-PEG copolymers were prepared by ring opening polymerization of lactide (LA) and glycolide (GA) (mole ratio of LA: GA 3:1) with or without polyethylene glycol (PEG). Amoxicillin loaded magnetic PLGA and PLGA-PEG nanoparticles were prepared by an emulsion-evaporation process (o/w). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) photomicrographs showed that the magnetic nanoparticles have the mean diameter within the range of 65-260 nm also they were almost spherical in shape. Magnetic nanoparticles prepared with PLGA showed more efficient entrapment (90%) as compared with PLGA-PEG (48-52%) nanoparticles. In-vitro release of amoxicillin from magnetic PLGA nanoparticles showed that 78% of drug was released over 24 hours. The amount of amoxicillin released from PLGA-PEG s was higher than PLGA.

• Molecules and Cells
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• v.38 no.6
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• pp.518-527
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• 2015

Controlled release of medications remains the most convenient way to deliver drugs. In this study, we precipitated gold nanoparticles with quercetin. We loaded gold-quercetin into poly(DL-lactide-co-glycolide) nanoparticles (NQ) and tested the biological activity of NQ on HepG2 hepatocarcinoma cells to acquire the sustained release property. We determined by circular dichroism spectroscopy that NQ effectively caused conformational changes in DNA and modulated different proteins related to epigenetic modifications and c ell cycle control. The mitochondrial membrane potential (MMP), reactive oxygen species (ROS), cell cycle, apoptosis, DNA damage, and caspase 3 activity were analyzed by flow cytometry, and the expression profiles of different anti- and pro-apoptotic as well as epigenetic signals were studied by immunoblotting. A cytotoxicity assay indicated that NQ preferentially killed cancer cells, compared to normal cells. NQ interacted with HepG2 cell DNA and reduced histone deacetylases to control cell proliferation and arrest the cell cycle at the sub-G stage. Activities of cell cycle-related proteins, such as $p21^{WAF}$, cdk1, and pAkt, were modulated. NQ induced apoptosis in HepG2 cells by activating p53-ROS crosstalk and induces epigenetic modifications leading to inhibited proliferation and cell cycle arrest.

• Macromolecular Research
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• v.17 no.5
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• pp.346-351
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• 2009

$TiCl(O-i-Pr)_3/SiO_2$ and $Ti(O-i-Pr)_4/SiO_2$ were prepared by immobilizing chlorotitanium (IV) isopropoxide ($TiCl(O-i-Pr)_3$) and titanium (IV) isopropoxide ($Ti(O-i-Pr)_4$), to pretreated silica. The effect of the polymerization reaction conditions on the catalytic activity and characteristics of the resulting PLA were investigated. The catalytic conversion, molecular weight and polydispersity index (PDI) of the PLA produced on the titanium alkoxide supported catalysts increased proportionally with the reaction temperature. When the PLA was synthesized in bulk polymerization, the PLA produced with the supported catalysts had higher molecular weight than those with homogeneous catalysts. The melting temperature of the polymer produced with silica supported alkoxide catalysts was approximately $170-180^{\circ}C$.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.141-144
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• 2000

Highly open porous polymer matrices are required for high density cell seeding, efficient nutrient, and oxygen supply to the cells cultured in the three dimensional matrices. However, there are severe problems of mass transfer limitations within the cell/scaffolds culture system. Thus we hypothesize that continuos-flow culture conditioning of cells with the scaffolds may improve the cell viability and the differentiated function. In this study, we fabricated porous PLGA scaffolds by using gas-foaming/salt-leaching method as previous described. Viscous PLGA gel paste contains ammonium bicarbonate particulates, acting as a gas-foaming agent as well as a salt-leaching porogen, were cast into Teflon mold and dried. Ammonium bicarbonate salt upon contact to an acidic aqueous solution evloves gaseous ammonia and carbon dioxide by itself. And we conjugated galactose moiety [AGA; $N-(aminobuty1)-O-{\beta}-D-galactopyranosyl-(1{\rightarrow}4)-D-glucoamide]$ to the terminal end group of a PLGA to increase the cell adhesion and matain the differentiated function of hepatocytes. Cell-seeded scaffolds were secured in a flow bioreactor chamber and exposed to continuous flow at 5 ml/min. As a result of our study, the high yield of hepatocytes attachment was accomplished by increasing the concentration of PLGA-AGA conjugate in polymer scaffolds and cells in the scaffolds under continuos flow condition maintained a high level of viability and albumin secretion rate of cultured hepatocytes showed a higher level that of control groups.

• Journal of Veterinary Clinics
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• v.13 no.2
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• pp.184-194
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• 1996

A comparative study of three absorbable suture materials of chromic catgut, Dexon II (a polyglycolic acid suture with a polycaprolate coating system) and Coated Vicryl (a polyglactin 910 suture with a glycolide-lactide-calcium stearate coating system) was undertaken in terms of tensile strength, breaking elongation, appearances of the suture materials in the subcutaneous layer of rats and of tissue reaction in the intramuscular layer of rats. The initial tensile strength of chromic catgut and the tensile strength after 21 days were about 1.55 kg and 0.19 kg, respectively. Those of Dexon II were about 2.01 kg and 0. 20 kg, respectively. Those of Coated Vicryl were about 2.39 kg and 0.48 kg, respectively. Coated Vicryl showed the highest tensile strength among the three materials during the whole period. On the other hand, Dexon II showed the highest breaking elongation among the three materials during the first week. But the breaking elongation of Dexon II rapidly continuously decreased during the whole period. The appearances of the suture materials in the subcutaneous layer of rats showed that chromic catgut was the fastest among the three materials, whereas it formed comparatively much connective tissue. The intramuscular absorption rate and tissue reaction of Dexon II were similar to those of Coated Vicryl. The intramuscular absorption rate of these was fairly late when compared with chromic catgut. And the tissue reaction appearance of these showed the formation of a granuloma with foreign body giant cells, macrothages and epitheloid cells by the 28th day in the experimental period.

• KSBB Journal
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• v.23 no.5
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• pp.408-412
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• 2008

The rosiglitazone loaded poly (lactide-co-glycolide) (PLGA) nanoparticles (NPs) were prepared by the emulsion-evaporation method and optimized for particle size and entrapment efficiency. The optimized particles were 140-180 nm in size with narrow size distribution and 80% entrapment efficiency at 1% w/w initial drug loading when prepared with 1-3% w/v of PVA as a surfactant. These particulate carriers exhibited controlled in vitro release of rosiglitazone for 36 hrs at a nearly constant rate after 4 hrs release. In conclusion, these results indicate that PLGA NPs have greater potential for oral delivery of rosiglitazone.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.51-51
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• 2011

PLA(Poly(lactic acid))는 옥수수, 사탕수수와 같은 천연재료에서 얻어진 젖산(lactic acid or lactide)을 원료로 하여 합성한 생분해성 고분자로서 석유자원의 고갈과 환경오염에 대한 관심이 고조됨에 따라 합성고분자를 대체할 재료로 각광받고 있다. 일반적인 PLA의 장점으로 투명성, 굽힘강성, 방수성, 가열밀봉성 등이 있으며, 단점으로는 열안정성, 내구성, 충격 강도 등이 있다. PLA를 섬유로 사용될 경우 농림 토목용 생분해성 소재 뿐 아니라 실크의 광택과 뛰어난 드레이프성, 감촉을 갖는 장점이 있다. 또한 수분을 신속하게 흡수하여 발산시키는 특성을 가지고 있고, 낮은 연소열과 가스량, 자기 소화성 등의 방염 특성 등을 지녀 의류 인테리어 소재로 매력적인 특성을 가지고 있다. PLA는 바이오고분자 중 비교적 높은 용융온도를 가지고 있지만 특히 염색 및 가공조건 등 고온 처리에 의해 기계적 강도가 저하되는 단점이 있어 내열성 및 기계적 강도의 향상이 필수적이다. 내열성 및 기계적 강도 향상을 위한 가장 손쉬운 방법은 고분자 사슬을 가교시키는 것으로서 열처리 또는 감마선, 전자선, 자외선 조사를 이용할 수 있는데 열에 의한 가교는 균일한 열전달과 고온이 필요하며 감마선 및 전자선 조사는 설비의 고비용과 방사성 노출 위험으로 인해 비친환경적이다. 따라서 다루기 쉽고 비용이 적게 들고 친환경적인 장점을 가진 자외선 조사법을 이용한 PLA의 광가교의 연구가 필요하다. 본 연구의 목적은 PLA 직물의 열안정성과 기계적 특성을 향상시키기 위해 광개시제와 자외선 조사를 이용하여 PLA 직물의 광가교를 수행하였다.

• Journal of Pharmaceutical Investigation
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• v.34 no.1
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• pp.1-14
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• 2004

A promising approach to the development of a new single-step vaccine, which would eliminate the requirement for multiple injections, involves the encapsulation of antigens into microspheres. Biodegradable poly(lactide-co-glycolide) (PLGA) microspheres gave us a bright insight for controling antigen release in a pulsatile fashion, thereby mimicking two or tree boosting injections. However, in spite of the above merits, the level of immunization induced by a single-shot vaccination is often lower tan two doses of alum-adsorbed antigen. Therefore, optima modification of the microsphere is essential for the development of single-step vaccines. In the review, we discuss the stability of antigen in microsphere, safety and non-toxic in human and encapsulation technology. Also, we attempted to outline relevant physicochemical properties on the immunogenicity of microsphere vaccine and attainment of pulsatile release pater by combination of different microsphere, as well as to analyze immunological data associated with antigen delivery by microsphere. Although a lot of variables are related to the optimized microsphere formulation, we could conclude that judicious choice of proper polymer type, adjustment of particles size, and appropriate immunization protocol along with a suitable adjuvant might be a crucial factor for the generation of long-lasting immune response from a single-step vaccine formulation employing PLGA microsphere.