Biomedical subjects

Hyung Dal Park

Publications and source records attributed to Hyung Dal Park.

4 recordsLinked to original sources

PubMed2006

Complement activation by sulfonated poly(ethylene glycol)-acrylate copolymers through alternative pathway.

Previously, novel poly(ethylene glycol) (PEG) and sulfonated PEG acrylate (PEG-SO(3)A/OA) copolymers were prepared as coating and/or blending materials for biomedical applications. Surfaces modified with copolymers exhibited increased anti-coagulation properties and decreased plasma adsorption level due to increased hydrophilic properties and reorientation characteristics of PEG/PEG-SO(3)A chains in water phase. As continuation study, anti-complement effects of PEG-SO(3)/OA copolymers were investigated in vitro, and compared with those of low-density polyethylene (LDPE) and PEG/OA. C3 activation by PEG-SO(3)/OA samples was lower than that by PEG/OA samples, which was attributed to decreased surface nucleophile level of samples. PEG-SO(3)/OA samples increased inhibition of Bb production, resulting in decreased C5 activation. Owing to reduced activations of C3 and C5, PEG-SO(3)/OA samples markedly decreased SC5b-9 levels in plasma.

Acrylates↗

PubMed2003

In vitro biocompatibility assessment of sulfonated polyrotaxane-immobilized polyurethane surfaces.

Sulfonated polyrotaxanes (PRx-SO(3)'s), in which sulfonated alpha-cyclodextrins (alpha-CDs) were threaded onto the poly(ethylene glycol) (PEG) segments in a PEG-b-poly(propylene glycol) (PPG)-b-PEG triblock copolymer (Pluronic) capped with benzyloxycarbonyl (Z)-L-phenylalanine (Z-L-Phe), were prepared as a novel surface-modifying biomaterial. Surface modification of the polyurethane (PU) was carried out by blending the PRx-SO(3)'s with a PU solution, followed by solution casting. The incorporated PRx-SO(3)'s led to the enhanced hydrophilicity by changing the surface properties of the PU matrix. Modified PUs showed the stable entrapment of the PRx-SO(3)'s with little extraction into water and enhanced mechanical properties after exposure to water compared to the PU control. The incorporated PRx-SO(3)'s repelled the proteins and kept them from closely approaching the surface areas, prevented platelet activation by thrombin, and effectively repelled bacteria. These results suggest that both the supramolecular structure of the polyrotaxanes and exposure of the sulfonated groups onto the surfaces contribute to these phenomena. Thus, surface modification with PRx-SO(3)'s is suggested to be useful for the fabrication of biocompatible medical devices.

Biocompatible Materials↗

PubMed2002

Anticoagulant activity of sulfonated polyrotaxanes as blood-compatible materials.

Polyrotaxanes, in which alpha-cyclodextrins (alpha-CDs) are threaded onto poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) triblock copolymers (Pluronic) capped with benzyloxycarbonyl(Z)-L-phenylalanine (Z-L-Phe), were prepared, and sulfopropyl groups were introduced to hydroxyl groups of alpha-CDs in the polyrotaxanes. The supramolecular structure and the chemical composition of the polyrotaxanes after the sulfonation were confirmed by 1H-NMR, 13C-NMR, and elemental analysis. Anticoagulant activity of the polyrotaxanes and sulfonated polyrotaxanes was measured by activated partial thromboplastin time (APTT). It was found that the polyrotaxanes and the sulfonated polyrotaxanes showed greater anticoagulant activity than Pluronic itself, suggesting that both the supramolecular structure of the polyrotaxanes and the sulfonated groups contribute to the inhibition of intrinsic coagulation factors. Finally, our designed polyrotaxanes are suggested to be a promising candidate when fabricating blood-compatible medical devices by blending with or coating on clinically used polymers.

Anticoagulants↗

PubMedDate not supplied

Heparin conjugated polylactide as a blood compatible material.

A heparin-conjugated biodegradable polymer (PLA-heparin) by the direct coupling of heparin to polylactide (PLA) was synthesized and characterized. The surface exposed heparin content associated PLA-heparin was measured to be 0.067 microg/cm2. PLA-heparin coated surface has shown higher hydrophilicity rather than control PLA surface. The clotting time of PLA-heparin conjugate measured by activated partial thromboplastin time (APTT) was significantly prolonged as compared to PLA. The bioactivity of bound heparin measured by APTT corresponds to 17.4% of free heparin. It has been also demonstrated that the conjugation of heparin suppresses the protein adsorption as well as the platelet adhesion. These results indicate that the unique property of bound heparin has an inhibiting influence on the coagulation, plasma protein adsorption, and subsequent platelet adhesion systems. This novel PLA-heparin conjugate could be applied as blood/tissue compatible biodegradable materials for implantable medical devices and tissue engineering.

Biocompatible Materials↗