SYNTHESIS AND CHARACTERIZATION OF NOVEL BIOMATERIAL SURFACES DECORATED WITH CHITOSAN DERIVATIVES

Abstract

New strategies of functionalization of poly(ԑ-caprolactone) (PCL), titanium and Ti6Al4V alloy with biomolecules were studied to improve the biocompatibility of these materials, used in many medical applications. Poly(ԑ-caprolactone) (PCL) surface was activated via alkaline hydrolysis and subsequently lactose modified chitosan (chitlac) was immobilized. Two kinds of chitlac, characterized by a different degree of derivatization of chitosan (respectively 64% and 9%) were synthetized and grafted to the activated PCL surface. Each step of the functionalization was investigated by a very sensitive surface technique, the Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), coupling with univariate and multivariate statistical analysis. Results showed the formation of a homogeneous layer of chitlac on the hydrolyzed PCL. Covalent grafting of chitosan on titanium and Ti6Al4V alloy was performed to improve biocompatibility, in terms of antibacterial properties. In detail, the chitosan was anchored to the metal surface, which was previously activated by carboxyl groups. Different pretreatments of the surface were studied, to identify the one, which could permit the highest functionalization efficiency of chitosan. The carboxylation of metal surfaces and the subsequent grafting with chitosan were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). Also an electrochemical technique, the cyclic voltammetry was employed to confirm the grafting of chitosan on metal surfaces and to evaluate the stability of immobilization procedure.