Morphology tuning of chitosan films via electrochemical deposition

Electrochemical deposition is a versatile surface modification technology for the realization of advanced coatings for biomedical applications. Here, we studied the effects of bath composition on the morphology of chitosan films prepared via cathodic polarization of titanium substrates in acidic baths. Since electrocoagulation processes strongly depend on local reduction at the cathode, in turn affected by the acid/base equilibrium in solution, we examined three different water-based acid bath (1 gl(-1)) at different pH ranges: acetic acid (pH 3-4), malonic acid (pH 2.7-3.2), and citric acid (pH = 2). Different coating morphologies, in terms of pore size and interconnection, were obtained when changing anion and solution pH. An increase in deposition mass per surface area was always observed when increasing polarization time, acetic acid bath showing the highest rates and yields and dried coating thickness up to 130 mu m. High deposition rates resulted in porous coatings, due to the entrapment of H-2 developed as a consequence of the local reduction processes. Gas evolution at the cathode surface determined the growth of pores in the deposit coatings and, depending on the process parameters, close vs. open porosity was observed. The possibility of tuning surface morphology of this class of films pave the way for the design of a novel class of medical devices, in which surface assisted tissue engineering approaches can be exploited on conventional metals for the realization of a new class of implantable prostheses. (C) 2012 Elsevier B.V. All rights reserved.