Visible-light-induced bactericidal properties of a novel thiophene-based linear conjugated polymer/TiO2 heterojunction.

ABSTRACT

The low utilization of visible light and the fast recombination of photogenerated electron-hole pairs are the two intrinsic defects that have hindered the antibacterial applications of TiO2. The addition of organic photocatalytic agents to form heterojunctions with TiO2 powder can effectively address these problems. A novel linear conjugated polymer poly[(thiophene-ethylene-thiophene)-thiophene-3-carboxylic acid decyl ester] (PTCD) was successfully synthesized via Stille coupling polymerization. PTCD and TiO2 can form a heterojunction photocatalyst (PTCD/TiO2), and this product was characterized using NMR and XRD. The UV-vis spectra showed that the absorption edge of the PTCD/TiO2 heterojunction extends to approximately 700 nm, which indicates that the visible-light utilization is greatly improved. Staphylococcus aureus (S. aureus) was selected as the target organism to test the photocatalytic antimicrobial activity of the material. Photogenerated electrons can undergo directional transmission of the PTCD polymer to TiO2 on the PTCD/TiO2 heterojunction to realize excellent antibacterial properties. With an optimized PTCD loading ratio of 30%, PTCD/TiO2 showed an antibacterial rate that was 14.5 times greater than that of pure TiO2 in 4 h under visible-light irradiation.