Photosensitive cellulosic materials based on a covalently grafted phenosafranin-modified silsesquioxane analog for bactericidal applications

Abstract

Light-triggered antimicrobial cellulose surfaces were obtained by the immobilization of a photosensitive phenosafranin dye (PSF) in a hybrid organic–inorganic silsesquioxane polymer applied on handsheets prepared from a standard bleached softwood pulp. These coatings were deposited by polycondensation of methyltriethoxysilane and an alkoxysilyl derivative of phenosafranin (TESPSF) obtained by the thiolene addition reaction and coupling of the succinic anhydride derivative with a primary amine group of PSF. TESPSF and coatings were characterized by advanced techniques in terms of chemical structure (1H, 13C, 29Si NMR, MS, ATR-IR), surface properties (SEM, EDX, water contact angles), and optical properties (UV, reflection light intensity, ISO brightness). The light-induced antimicrobial activity of sheets of paper coated with new materials showed the inhibition of the growth of the bacteria Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739. The cytotoxicity studies of modified cellulose surfaces were performed using erythrocyte lysis assays under both dark and light conditions exhibited no toxicity on erythrocytes. Thus, the new material did not reveal harmful effects on erythrocytes, regardless of the presence and absence of light.