• KSBB Journal
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• v.18 no.2
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• pp.107-110
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• 2003

Biodegradable polymers, poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate) (PHB), and medium chain length polyhydroxyalkanoates (MCL-PHA) containing rose bengal (model drug) were coated onto the surface of stainless steel (stent materials) and their in vitro release characteristics were investigated. Drug release increased with; decreasing PLGA concentration, increasing rose bengal concentration, and Increasing dip-coating duration. The order of drug release from the polymer coating was: PHB > PLGA > MCL-PHA. These results suggest that drug release can be controlled by: changing the concentration and type of polymer, the drug concentration, and the dip-coating duration.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1333-1336
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• 2014

Expanded polytetrafluoroethylene (ePTFE) grafts have been used as vascular access for many patients suffering from end stage renal disease. However, the vascular graft can cause significant clinical problems such as stenosis or thrombosis. For this reason, many studies have been performed to make drug eluting graft, but initial burst is major problem in almost drug eluting systems. Therefore we used biodegradable polymer to reduce initial burst and make sustained drug delivery. The ePTFE grafts were dipped into a paclitaxel-dissolved solution and then PLGA-dissolved solution was passed through the lumen of ePTFE. We analyzed whether the dose of paclitaxel is enough and the loading amount of PLGA on ePTFE graft increases according to the coating solution's concentration. Scanning electron microscope (SEM) images of various concentration of PLGA showed that the porous surface of graft was more packed with PLGA by tetrahydrofuran solution dissolved PLGA. In addition, in vitro release profiles of Ptx-PLGA graft demonstrated that early burst was gradually decreased as increasing the concentration of PLGA. These results suggest that PLGA coating of Ptx loaded graft can retard drug release, it is useful tool to control drug release of medical devices.

• Polymer(Korea)
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• v.36 no.3
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• pp.326-331
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• 2012

In this study, expanded poly(tetrafluoro ethylene) (ePTFE) graft was modified to be used as a hemodialysis vascular access. Biodegradable poly(D,L-lactide-$co$-glycolide) (PLGA) was coated onto the inner surface of ePTFE graft with paclitaxel, which is often used as an anti-cancer agent and for reducing neointimal hyperplasia. Surface characterization before and after PLGA coating was carried out by SEM and ATR-FTIR. Porous sturcture of ePTFE was maintained after coating of PLGA solution. The amounts of coated PLGA and paclitaxel determined by ATR-FTIR and HPLC were 1.96 and 0.263 mg/$cm^2$, respectively. Young's modulus was decreased and tensile strength was increased by PLGA coating. Released paclitaxel as a function of incubation time was monitored by HPLC. Approximately 35% of coated paclitaxel was released steadily for 4 weeks with the biodegradation of PLGA. From these results, it is expected that the effect of paclitaxel on reducing neointimal hyperplasia and stenosis is maintained for a long time.

• Polymer(Korea)
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• v.33 no.6
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• pp.620-624
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• 2009

Biomedical metal implants have been used clinically for replacement, restoration, or improvement of injury bodies based on high mechanical properties, but it has some risks such as the inflammatory, late thrombosis, or restenosis due to the low biocompatibility and toxicity. In various techniques of surface treatment developed to preserve these drawbacks, this study examined the electrospray coating technology with biodegradable poly (lactic-co-glycoic acid) (PLGA) on metal surface. Based on fundamental examination of electrospraying and solution parameters, the surface morphology of coated film was closely related to the boiling point of solvent, in-flight distance, and droplet size. The thickness of polymer film was linearly proportional to the emerged volume. This result exhibits that the polymeric droplets were continuously deposited on the polymer film. Therefore, the electrospray coating technology might be applied into the fabrication of single/multi-layered polymer film in nano-/micro-thickness and the control of the topology for biomedical metal implants including stents.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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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.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.36-43
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• 2020

A biliant stent was fabricated using a magnesium alloy wire, a biodegradable metal. In order to control the fast decomposition and corrosion of magnesium alloys in vivo, magnesium alloy wires were coated with biodegradable polymers such as polycaprolactone (PCL), poly(propylene carbonate) (PPC), poly (L-lactic acid) (PLLA), and poly (D, L-lactide-co-glycolide) (PLGA). In the case of PPC, which is a surface erosion polymer, there is no crack or peeling compared to other polymers (PCL, PLLA, and PLGA) that exhibit bulk erosion behavior. Also, the effect of biodegradable polymer coating on the axial force, which is the mechanical property of magnesium alloy stents, was investigated. Stents coated with most biodegradable polymers (PCL, PLLA, PLGA) increased axial forces compared to the uncoated stent, reducing the flexibility of the stent. However, the stent coated with PPC showed the axial force similar to uncoated stent, which did not reduce the flexibility. From the above results, PPC is considered to be the most efficient biodegradable polymer.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.4
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• pp.298-304
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• 2014

Purpose: This preliminary rabbit study was conducted to evaluate the effect of recombinant human transforming growth factor-${\beta}2$ (rhTGF-${\beta}2$)/poly lactic-co-glycolic acid (PLGA) coating on osseointegration of the titanium (Ti) implant. Materials and methods: Eight Ti implants were anodized with 300 voltages for three minutes. Four of those were coated with rhTGF-${\beta}2$/PLGA by an electrospray method as the experimental group. The implants were placed into tibiae of four New Zealand rabbits, two implants per a tibia, one implant per each group. After 3 and 6 weeks, every two rabbits were sacrificed and micro-computed tomography (microCT) was taken for histomorphometric analysis. Results: In scanning electron microscope (SEM) image, the surface of rhTGF-${\beta}2$/PLGA coated Ti implant showed well distributed particles. Although statistically insignificant, microCT analysis showed that experimental group has higher bone volume / total volume (BV/TV) and trabecular thickness (Tb.Th) values relatively. Cross sectional view also showed more newly formed bone in the experimental group. Conclusion: In the limitation of this study, rhTGF-${\beta}2$/PLGA particles coating on the Ti implant show the possibility of more favorable quantity of newly formed bone after implant installation.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.397-402
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• 2007

Restenosis after percutaneous coronary intervention (PCI) continues to be a serious problem in clinical cardiology. To solve this problem, drug eluting stents (DES) with antiproliferative agents have been developed. Variable local drug delivery systems in the context of stenting require the development of stent manufacture, drug pharmacology and coating technology. We have worked on a system that integrates electrophoretic deposition (EPD) technology with the polymeric nanoparticles in DES for local drug delivery and a controlled release system. The surface morphology and drug loading amount of DES by EPD have been investigated under different operational conditions, such as operation time, voltage and the composition of media. We prepared poly-D,L-lactide-co-glycolic acid (PLGA) nanoparticles embedded with curcumin, which was done by a modified spontaneous emulsification method and used polyacrylic acid (PAA) as a surfactant because its carboxylic group contribute negative charge to the surface of CPNPs (?53.5 ± 5.8 mV). In the process of ‘trial and error' endeavors, we found that it is easy to control the drug loading amount deposited onto the stent while keeping uniform surface morphology. Accordingly, stent coating by EPD has a wide application to the modification of DES using various kinds of nanoparticles and drugs.

• Progress in Medical Physics
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• v.20 no.3
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• pp.125-131
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• 2009

In this study, the paclitaxel eluting stent (PES) was prepared by coating a biliary stent with paclitaxel using various biopolymer such as poly (vinyl acetate) (PVAc), poly (lactic-co-glycolic acid) (PLGA), Silicone rubber for restenosis prevention in gastrointestinal disease by a dip-coating method. Drug contents of PES were increased as surface area of stent, concentration and molecular weight of coating polymer increase. In $^1H-NMR$ specta, we know that drug did not change by confirming specific peaks of paclitaxel in PES. As shown in SEM image, PES prepared using various biopolymer is coated clearly and regularly except Silicone rubber coating polymer. In in vitro cell cytotoxicity test, bare stent showed low cytotoxic effect against CT-26 colon carcinoma cell line on 3 day. However, PES coated with PLGA 502H showed the highest cytotoxicity because PLGA 502H is biodegradable polymer and has less molecular weight than other coating polymer. These results suggest that PES coated various biopolymer can be prevented restenosis in gastrointestinal disease.

• Biomolecules & Therapeutics
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• v.16 no.4
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• pp.425-430
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• 2008

The objectives of this study were to prepare PLGA film onto the surface of the capsular tension ring (CTR) for controlled drug release and investigate the influence of plasticizers, the test drug and measurement conditions on flexibility of the film. Film solutions were prepared by dissolving PLGA, plasticizer (triethyl citrate, TEC or polyethylene glycol, PEG), test drug (dexamethasone) in ethyl acetate then films were prepared by spray coating and evaporation method. Then, the flexibility of PLGA film was determined by elongation test. The addition of plasticizer, PEG or TEC to PLGA copolymer caused a depression of glass transition temperature ($T_g$) and the elasticity of PLGA films increased. The addition of dexamethasone to the PLGA/TEC matrix decreased the flexibility of film. Dimensional factors of the PLGA films such as width and thickness were significantly influenced on flexibility of films and film length and elongation speed had no considerable influence on elongation of films. In this study, sufficiently flexible and stable PLGA films capable of being coated onto CTR could be prepared. This PLGA films can be used as a platform for local drug delivery.