DC discharge plasma modification of chitosan/gelatin/PLLA films: Surface properties, chemical structure and cell affinity

The work was aimed to study an effect of direct current discharge on chemical structure, surface properties and cell response to the plasma modified composite films. The film samples were prepared by solvent casting from colloidal solution of the ternary blend of chitosan, gelatin and poly(L,L-lactide), PLLA, obtained by solid-state reactive blending (SSRB), in CH2Cl2 and treated with air plasma at pressure of 10–20 Pa and a discharge current of 50 mA for 60 s. The model film samples casted from the initial components were treated and studied as well. Contact angle of wettability measurements of the films showed that plasma modification led to increase of hydrophilicity and surface energy. Contact angle changes after plasma treatment of chitosan/gelatin/PLLA (CGP) film were more similar to those for the poly(L,L-lactide) film. X-ray photoelectron spectroscopy (XPS) data confirmed that a surface layer of the blend films was enriched with a polyester component. However, study of mouse fibroblast (L929) attachment and growth on the films showed that the CGP film provided an enhanced cell growth compared to this on the poly(L,L-lactide) film. Plasma modification of the polymer films resulted in a substantial increase in fibroblast viability on the plasma treated poly(L,L-lactide) films and to a rather strong decrease of cell growth on the plasma treated CGP and chitosan ones. Thus, plasma surface modification could be proposed as a good tool to control cell response on the material surface.