Papers by Author: Gun Woo Kim

Abstract: In vitro cell behaviors of calvarial osteoblasts (MC3T3) were evaluated by seeding them on both the surface and inside of in situ hyaluronic acid-poly(ethylene oxide) (HA-PEO) hydrogel, either after or before incorporation of mixture micro-particles of hydroxyapatite-β-tricalcium phosphate on/inside the hydrogel, respectively. Cellular behaviors such as adhesion and proliferation on the surface and inside the gel were evaluated with light microscopy and a microplate reader by focusing on the interactions of cell-HA-PEO as well as cell-hydroxyapatitetricalcium phosphate micro-particle surface in the gel. Cell adhesion and spreading seemed to be enhanced by supplying the micro-particles to the inside the HA-PEO hydrogel, compared to the results of the HA-PEO hydrogel itself.

Abstract: Characterization of an hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel was performed by changing the number of side arms in a PEO molecule. Verification of grafting chemistry and mechanical strength, as well as swelling behaviors and surface morphologies of the HA-PEO hydrogels were analyzed by employing different x-linking molecular weights (MW) of PEO ranging from 1.7 to 5.0 kDa at a fixed low MW HA in the hydrogel network. Methacrylation to the HA successfully obtained via Michael type reaction between the methacrylate arm groups in HA and the thiol end groups in PEO was observed by XPS. Hydrogel formation was markedly dependent upon the numbers of thiol groups in the PEO molecule. Furthermore the lower MW PEO-based HA hydrogel demonstrated stronger mechanical properties but lower water absorption and the smaller pore sizes on its surface and cross section.

Abstract: Though hyaluronic acid (HA)-based hydrogel has drawn great attention in biomedical society, it’s long molecular weights sometimes have been problematic due to its difficulty in handling. After reduction of its high molecular weight into smaller sizes with various concentrations of hydrogen chloride solutions, its chemical and biological properties have been examined by changes in viscosity, FTIR spectroscopy and gel permeation chromatography as well as cellular interactions. While FTIR analysis indicated maintenance of its original chemical structures, its viscosity has been remarkably reduced and its extent was dependent upon the employment of acid concentrations. After controlling its molecular weight to approximately 100 kDa and coupling of aminopropymethacrylate to the treated HA, we evaluated in vitro cellular interactions and cell proliferations of the HA-poly(ethylene oxide) (PEO) hydrogel.

Abstract: This study is to develop a novel method for preparation of the chitosan scaffold having interconnected open pore structure and controlled pore distribution. For this, the effects of addition of non-solvent on chitosan solution were estimated. The porous scaffolds were typically prepared by solid-liquid separation and subsequent sublimation of solvent. Alcohol was used as non-solvent for chitosan. The difference of freezing temperature of each of the components induced the liquidliquid and the liquid-solid phase separation via demixing solution (solvent/non-solvent/chitosan). The morphology, heterogeneous pore distribution and mechanical properties of the scaffolds were examined. The addition of non-solvent in chitosan solution was to make the controlled homogeneous micropores and improved interconnectivity between pores without any surface skin layer. For control chitosan scaffold, the pore size was mainly about 80~100 μm. On the contrary, Pore diameters could be controlled mainly within the range 30~100 μm, with a variation of solvent/non-solvent ratio. The number of minute pore (4~25 μm) over chitosan scaffold increased with increasing ratio of non-solvent. New prepared scaffold exhibited larger value of breaking elongation, more elasticity, but less tensile strength than that of control scaffold.