Anion exchange nanofiber materials activated by daylight with a dual antibacterial effect

Abstract

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(¹Δ_g), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O₂(¹Δ_g), 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(¹Δ_g), 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.