Jong-Bae Choi

Characterization and Antimicrobial Property of Poly(Acrylic Acid) Nanogel Containing Silver Particle Prepared by Electron Beam

In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition, the particle size and zeta-potential were confirmed by a particle size analyzer (PSA). The antibacterial properties of the nanogels were evaluated by paper diffusion test. The Ag/PAAc nanogels had an antibacterial effect against Escherichia coli and Staphylococcus aureus. The nanogels also demonstrated a good healing effect against diabetic ulcer. The size of the Ag/PAAc nanogels decreased with increasing irradiation doses, and the absolute value of the zeta potential increased with increasing irradiation doses. Also, the Ag/PAAc nanogels exhibited good antibacterial activity against both Gram-negative and Gram-positive bacteria. In in vivo wound healing, the Ag/PAAc nanogels have a good healing effect.

Physicochemical characterization of gelatin-immobilized, acrylic acid-bacterial cellulose nanofibers as cell scaffolds using gamma-irradiation

Bacterial cellulose (BC) has been shown to have a high-burst pressure, high-water contact, and ultrafine highly nanofibrous structure similar with that in a natural extracellular matrix (ECM). In the present study, we developed a BC-based functional scaffold for tissue engineering using radiation technology. BC was generated by Gluconacetobacter hansenii TL-2C. Acrylic acid (AAc) was grafted onto BC surfaces under aqueous conditions using gamma-ray irradiation. The characterization of the scaffold was performed by scanning electron microscopy, ATR-FTIR spectroscopy, a toluidine blue O assay, and 2,4,6,-trinitro-benzensulfonic acid assay. AAc was grafted on the BC under gamma-ray irradiation. Gelatin was chemically conjugated on the AAc-BC scaffolds through EDC chemistry. The morphology of the modified BC nanofibers did not change, while representative features of AAc and gelatin were maintained. The adhesion and spreading of human mesenchymal stem cells was improved on the gelatin-AAc-BC nanofibers compared to unmodified BC and AAc-BC nanofibers. Our results suggest that gelatin-immobilized BC nanofiber scaffolds can be a promising way to fabricate three-dimentional, nanofibrous scaffolds that accelerate cell behavior for biomedical applications.

감마선 조사에 의한 조직공학용 알긴산 나노섬유의 분해 영향

Alginate, a linear un-branched polysaccharide derived from seaweed has shown great potential as a cell scaffold for the regeneration of many tissues. However, alginate is not naturally enzymatically degraded in ionically crossliked alginate htdrogels exhibit a remarkably slow degradation rate, which is typically months to years for their complete removal from injection site. The ionizing irradiation degrades polysaccharides through the free radical-induced scission of glycosidic bonds of alginate. In this work, alginate/PEO nanofiber was irradiated 60Co γ-rays in the dose range of 50-300 kGy. This approach offers control over the degradation rate by varying the gamma-irradiation dose degree, as increasing the gamma-irradiation dose degree can increase the vulnerability of alginate nanofibers to hydrolysis under in vitro condition. And, the ability of electrospun a cell adhesive peptide Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) modified alginate and unmodified alginate nanofibrous scaffolds to support human mesenchymal stem cell (hMSCs) attachment and spreading was greatly enhanced on the adhesion ligand-modified compared to unmodified nanofibers, demonstrating the initial promise of this electrospun polysaccharide material with defined nanoscale architecture and cell adhesive properties for tissue regeneration applications.

Effect of addition of soybean oil and gamma-ray cross-linking on the nanoporous HDPE membrane

A nanoporous high-density polyethylene (HDPE) membrane was prepared by a wet process. Soybean oil and dibutyl phthalate (DBP) were premixed as codiluents, and gamma-rays were used for the cross-linking of HDPE. The pore volume of the nanoporous HDPE membranes with soybean oil was affected by the extracted amount of oil. The tensile strength of the membrane improved with an increasing absorbed dose up to 60 kGy, but decreased at 80 kGy due to severe degradation. The ionic conductivity of the nanoporous HDPE membrane did not really change with an increasing absorbed dose because the pores had already been formed before the gamma-ray radiation. Finally, the electrochemical stability of the HDPE membrane increased when the absorbed dose increased up to 60 kGy.