RESUMO
A novel straightforward approach has been proposed to generate in situ, under light activation and in aerated media, visible-light absorbing and well-defined titanium-based nanoparticles (NPs) in solution and in an epoxide matrix using titanium derivative complexes/iodonium salt photoinitiating systems. The nature of the solvent and oxygen plays a decisive role, and two mechanisms involved in these syntheses are operative, i.e. a photofragmentation/addition process (in toluene and isopropanol) and a photoinduced sol-gel reaction (in isopropanol).
RESUMO
A green photoinduced method for the modification of a biodegradable and biocompatible polymer, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) has been successfully carried out using two types of monomers with potential antibacterial effects, i.e., 2-[(methacryloyloxy)-ethyl] trimethylammonium chloride (META) and an ampicillin-derived monomer. The photografting process is conducted through a photoinduced free-radical process employing a thiocarbamate-based photoinitiator in an aqueous medium. Under appropriate conditions, radicals are generated from the PHBHV surface, thus initiating the UV-mediated photopolymerization of methacrylate or methylacrylamide-derived monomers from the surface of PHBHV films. The photochemical mechanism of the thiocarbamate photolysis is entirely described by the electron spin resonance/spin-trapping technique and laser flash photolysis, and the modified-PHBHV films are extensively characterized by fluorescence experiments, water contact angle, and XPS measurements. Finally, a primary investigation is conducted to support the antibacterial property of the new functionalized films against Escherichia coli and Staphylococcus aureus, and their cytocompatibility with NIH-3T3 fibroblastic cells is evaluated.