Improvement of crosslinked gelatin for in vitro cell culture by plasma surface treatment

Abstract

To study the effects of plasma treatment on the physical and biological properties of crosslinked gelatin. In the first part, nitrogen, oxygen, and air glow discharges powered by AC 50Hz were used to treat type A gelatin film crosslinked by dehydrothermal process. The water contact angle of gelatin films was decreased with increasing plasma treatment time. The treatment of nitrogen, oxygen, and air plasma up to 30 seconds had no effects on the surface roughness of gelatin film. N-containing functional groups generated by nitrogen and air plasma, and O-containing functional groups generated by oxygen and air plasmas were incorporated onto the film surface. These functional groups were found to increase with increasing treatment time. The storage temperature of plasma-treated samples had an influence on the recovery of wettability. In vitro test using rat bone marrow mesenchymal derived stem cells (MSCs) revealed that the number of cells attached on plasma-treated gelatin films was significantly increased compared to untreated samples. In addition, among three types of plasmas used, nitrogen plasma treatment provided best MSCs attachment on gelatin surface. The results suggested that a type A gelatin film with water contact angle of 27-28o and the O/N ratio of 1.4.is most suitable for MSCs attachment. In the second part, PICP plasma system, one of high energy plasma system, was introduced to treat gelatin films. Nitrogen was selected to generate PICP plasma since it induced best cell attachment as found in the first part. PICP could alter the surface properties of gelatin film but does not influence the thermal property and the degree of crosslinking of the film. The hydrophilicity, surface energy, and surface roughness of gelatin films were promoted by increasing the number of applied pulses of PICP. Biocompatibility results showed that PICP treatment could enhance cell attachment on the surface of gelatin film. The study implied that both AC 50Hz and PICP can be used to enhance the physical and biological properties of gelatin film.