A new class of nitrobenzoic acid-based AIE photosensitizers for highly efficient photodynamic antibacterial therapy

基于硝基苯甲酸结构的新型AIE光敏剂的光动力抗菌作用

hotodynamic therapy(PDT)has been drawing more and more attention in the antibacterial field.Traditional photosensitizers(PSs)tend to aggregate in aqueous media,which reduces the generation of reactive oxygen species(ROS)and seriously affects the photodynamic efficacy.Many efforts have been made to prevent aggregation of traditional PSs.By contrast,aggregation-induced emission PSs(AIE-PSs)take advantage of aggregation to boost ROS generation and fluorescence intensity.However,the efficacies of the reported antibacterial AIE-PSs are poor.Herein,we report a new class of highly effective antibacterial AIE-PSs based on nitrobenzoic acid structure.TTVBA,a negatively charged AIE-PS,can not only selectively kill spherical bacteria(Staphylococcus aureus(S.aureus))rather than rod-shaped bacteria(Escherichia coli(E.coli)),but also be easily extended to several AIE-PSs(TTVBP1–3)with positive charges and broad-spectrum antibacterial activity.We demonstrate that TTVBP2 can kill3.0 log_(10)of S.aureus at very low concentration(125 nmol L^(-1)),TTVBP3 can kill 4.7 log_(10)of Staphylococcus epidermidis(S.epidermidis)at a concentration of 1μmol L^(-1)and 3.8 log_(10)of E.coli at 5μmol L^(-1),thus enabling them among the most effective antibacterial AIE-PSs reported so far.Meanwhile,these AIE-PSs exhibit excellent wash-free imaging ability for bacteria by simple mixing with bacteria.We thus envision that TTVBA,a nitrobenzoic acid-based extendable AIE-PS,provides a new route for the design of AIE-PSs in antibacterial treatment.

光动力疗法在抗菌领域中的应用备受关注.传统的光敏剂在水性介质中容易聚集,从而减少活性氧的产生并严重影响其光动力抗菌疗效.为了减少传统光敏剂的聚集,研究人员做出了许多努力.与之相反,聚集诱导发光型的光敏剂(AIE-PSs)利用其聚集的优势,不仅增加了活性氧产量,而且增强了荧光强度.然而目前有关抗菌型AIE-PSs的研究仍处在发展阶段,相关报道也非常有限.我们在此首次报道了系列基于硝基苯甲酸结构的高效抗菌型AIE-PSs.其中带负电荷的TTVBA不仅可选择性地灭杀球形细菌(如金黄色葡萄球菌),而且易于被扩展成多种带正电荷且具有广谱抗菌性能的AIE-PSs(如TTVBP1–3).我们发现,TTVBP2在125 nmol L^(-1)的低浓度下,即可灭杀3.0 log_(10)金黄色葡萄球菌;TTVBP3在1μmol L^(-1)浓度下可灭杀4.7 log_(10)表皮葡萄球菌,在5μmol L^(-1)浓度下可灭杀3.8 log_(10)大肠杆菌,成为目前已报道的最有效的抗菌AIE-PSs.此外,这些AIE-PSs直接与细菌混合后,即对细菌具有出色的免洗成像能力.因此,我们认为基于硝基苯甲酸结构的TTVBA为未来高效抗菌光敏剂的设计提供了崭新思路.