Anion exchange nanofiber materials activated by daylight with a dual antibacterial effect†
Anion exchange polystyrene nanofiber materials (AE) were prepared by electrospinning followed by two-step functionalization of the nanofiber surface by chlorosulfonic acid and ethylendiamine. The photoactive character of these materials was introduced through adsorption of the tetra-anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin photosensitizer (TPPS-AE) on the nanofiber surface or by encapsulation of the nonpolar 5,10,15,20-tetraphenylporphyrin photosensitizer (AE(TPP)) into the nanofibers. Anion exchange nanofiber materials with porphyrins are characterized by a high ion-exchange capacity, photogeneration of singlet oxygen O2(1Δg), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O2(1Δg), the nanofibers exhibited oxidation of the external substrates in aqueous solution and an efficient antibacterial effect when activated by simulated daylight. Adsorption of both TPPS and I− on the surface of AE led to the formation of more efficient I-TPPS-AE materials. Rapid photooxidation of I− by O2(1Δg), and the formation of another cytotoxic species, I3−, on the surface of the nanofibers were responsible for the increased antibacterial properties of I-TPPS-AE and the prolonged antibacterial effect in the dark.