Investigating the effect of surface energy of chitosan/titanium dioxide nanocomposite films on their antibacterial behavior Mahdieh Raeesi1, Hossein Ali Khonakdar2, Javad Seyfi3 1 Chemical Engineering Department, Central Tehran Branch, Islamic Azad University, Tehran, Iran 2 Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden, Germany 3 Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran Abstract Chitosan is the most important derivative of chitin, and is obtained by partial deacetylation of chitin in the solid state under alkaline conditions or by enzymatic hydrolysis. Since chitosan is biocompatible, biodegradable and non-toxic, it has found a vast range of applications within the biomedical applications such as tissue engineering and wound healing [1]. In order to improve some properties of chitosan like cell adhesion, different nano-scale inorganic materials have been incorporated into the chitosan matrix. It was shown that materials such as titania, zirconia and alumina could enhance the cellular behavior if they are used in nano-scale sizes [2]. One of the most important characteristics of chitosan is its antibacterial property which could be utilized especially in wound dressing applications. In this research, the thin films based on chitosan and titanium dioxide (TiO2) nanoparticles are first fabricated, and then, the effect of nano-TiO2 concentration on the bacterial adhesion is assessed. To this end, the surface energy is calculated by measuring the contact angles of different liquids, and then, an attempt is made to establish correlations between the surface energy of the films and the antibacterial property. Keywords: Chitosan; Antibacterial; Surface Energy References: [1] R. Jayakumar, R. Ramachandran, V.V. Divyarani, K.P. Chennazhi, H. Tamura, S.V. Nair, Int. J. Bio. Macromol. 48 (2011) 336. [2] P.A. Ramires, A. Romito, F. Cosentino, E. Milella, Biomaterials 22 (2001) 1467.