Nature sunlight-driven polymer/TiO2 antimicrobial agent for the killing of multidrug-resistant bacteria with enhanced photocatalytic activity

Photocatalytic antimicrobial technology is one of the most effective methods to treat multidrug resistance (MDR) bacteria-caused infections. Nevertheless, its practical application is hindered because of the low light utilization rate and the weak photocatalytic antimicrobial properties. In this work, a heterojunction photocatalyst consisting of an organic-conjugated polymer and a biological semiconductor is prepared to kill MDR bacteria under sunlight. The organic semiconductor poly[2,11′-thiopheneethylenethiophene-alt-2,5-(3-carboxyl)thiophene] (PThC) with carboxyl can via weak interactions such as hydrogen bonding combine with the surface hydroxyl group of TiO2 to achieve a high stability. The PThC/TiO2 photocatalyst possesses improved antibacterial activity because of the formation of heterostructure that achieves visible region spectrum absorption, and the reduction of the photocarrier recombination rate to produce more reactive oxygen species. The use of PThC/TiO2 in the inactivation of Methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) revealed that the antibacterial activity was greatest when the PThC/TiO2 dose was 30% and the concentration was 0.2 mg/mL. Under LED white light irradiation, 7.31 log MRSA (100%) could be inactivated within 30 min, and the inactivation efficiency of E. coli reached 100% within 3 h. Under natural sunlight, it also has a significant antimicrobial action.