Layer-by-layer coating of photoactive polymers for biomedical applications

Layer-by-layer (LbL) assembly is a versatile technique for the development of multilayered films with tailored characteristics at the nanometer scale. In this work, photoactive nanostructured films were prepared by LbL assembly of biocompatible photozymes: an anionic zwitterionic copolymer, poly(sodium styrene sulfonate-co-vinyl naphtalene-co-3-dimethyl(methacryloylethyl) ammonium propane sodium sulfonate; ZI) and a cationic polyelectrolyte, chitosan-g-fluorescein (CHFL) on a genipin-crosslinked gelatin substrate (G_GP). The correct organization of the multilayered coating was demonstrated by the static contact angle values, showing an alternate trend. FTIR-ATR spectra showed the main absorption bands of ZI, such as asymmetric (1125 and 1180cm ^-1) and symmetric (1036cm ^-1) OSO stretching and SOC stretching (1009cm ^-1), also confirmed by Energy-dispersive X-ray spectroscopy (EDS) spectra. UV-vis spectra showed the typical fluorescein absorbance peak of CHFL after the 8th layer, which intensity increased with increasing the even layer number. The absorption peak of G_GP (605-610nm) probably masked the weak FL absorbance for coated samples with a lower layer number than 8. Scanning electron microscopy (SEM) results suggested the agglomerate presence on the coated surface. The obtained nanostructured films are expected to be promising candidates for carrying out efficient electron transfer process, responsible for the anti-microbial activity (ZI) or the osteointegration ability (CHFL) of the coating.