Surface properties of chitosan films modified with polycations and their effects on the behavior of PC12 cells

A series of composite films were prepared by blending chitosan with three polycations, poly(L-lysine), polyethyleneimine, and poly-L-ornithine, in specific blend proportions. The surface properties of the composite films, including surface topography, chemistry, and wettability, were examined by atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle assay, respectively. For all composite films, blending with different polycations produced different nanoscaled surface topographical features (particles, granules, fibers, and islands) in addition to inducing changes in surface chemistry and wettability. PC12 cells were cultured on these composite films to evaluate the effects of surface properties on cell behavior. The PC12 cell behavior was holistically affected by surface topography, chemistry, and wettability; the cells also displayed responses to surface topography. On the surfaces with fiber topographic features, the PC12 cells exhibited significantly higher levels of adhesion, proliferation, and differentiation when compared to particle, granule, or island dominant surfaces. It appears that the surface topography of chitosan and chitosan-derived materials may play an important role in regulating nerve cell behavior and that topographic modification can be utilized for the applications of chitosan and chitosan-derived materials in nerve or other tissue regeneration.