MODIFICATION OF HYDROPHOBIC SURFACE WITH POLYASPARTAMIDE-BASED POLYCATIONS FOR BIOMEDICAL APPLICATION

Abstract

A convenient way for the achievement of polymer-based solid materials for specific biomedical applications is grafting the appropriate macromolecules onto the surfaces in order to confer them specific properties. To date many approaches have been used to covalently modify polymeric surfaces, and among them chemoselective coupling reactions, usually referred as “click” reactions, gained much attention thanks to simple procedure with high reaction rate under mild reaction conditions (at normal temperature and pressure) [1]. In particular, radical-initiated thiol-yne “photo-click” chemistry has been demonstrated as an effective way to functionalize efficiently surfaces. This method gives also the possibility to avoid the presence of residual metal impurities and to increase the density of surface functionalization, thanks to the possibility to yield bis-addition products on triple bonds [2]. In this frame, copper catalysed “click” chemistry was recently used to confer antibacterial and antibiofilm properties to propargylated PLA surfaces by immobilization of polyquaternary ammoniums.[3] Here, this approach was enlarged to thiol-yne “photo-click” chemistry that was used to link a polyaspartamide copolymer, bearing positive permanent charges to PLA surfaces. Therefore a copolymer of α,β-poly(N-2-hydroxyethyl)-DL-aspartamide bearing in the side chains ethylendiammine (EDA), carboxypropyl trimethylammonium (CPTA) groups and lipoic portions was synthesized (PHEA-EDA-CPTA-LA). In parallel, a hydrophobic “clickable” propargilated PLA94 surface was prepared according to a previously described procedure.[3] After proper reduction of the disulfide bridge, PHEA-EDA-CPTA-LA was conjugated to the propargilated PLA94 surface by photo-chemical reaction between free thiols and propargilic groups. To confirm the covalent surface modification and quantify the density of surface functionalization, SEC and XPS analysis were performed. Further, it was investigated on the biocompatibility of PHEA-EDA-CPTA-LA modified PLA94 surfaces monitoring in vitro the proliferation of mouse fibroblasts.