Assessing the Biocidal Activity and Investigating the Mechanism of Oligo-p-phenylene-ethynylenes

A number of oligo-p-phenylene-ethynylenes (OPEs) have exhibited excellent biocidal activity against both Gram-negative and Gram-positive bacteria. Although cell death may occur in the dark, these biocidal compounds are far more effective in the light as a result of their abilities to generate cell-damaging reactive oxygen species. In this study, the interactions of four OPEs with Escherichia coli and Staphylococcus aureus have been investigated. Compared to the OPEs with quaternary ammonium salts (Q-OPE), the OPEs with tertiary ammonium (T-OPE) effectively kill many more bacterial cells under light irradiation, presumably by severe perturbations of the bacterial cell wall and cytoplasmic membrane. According to the findings from this study, such intriguing light-induced antibacterial behavior is probably attributed to the combination of bacterial membrane disruption and the interfacial or intracellular generation of singlet oxygen or other ROS. Singlet oxygen was proved to be formed from irradiation of the OPEs, whereas the varying cell membrane perturbation abilities of OPEs enhance antibacterial activity.