Constructions And Properties Of Bodipy-Based Antibacterial Materials

Bacterial infections are dangerous to the health of human being,and the rising bacterial resistance has become a danger to human health.Therefore,it is an urgent need to develop novel bacterial detection and antibacterial agents.Boron dipyrromethene derivatives（BODIPY）are the most commonly used clinical photosensitizer in photodynamic therapy（PDT）,which can convert environmental oxygen to toxic reactive oxygen species（ROS）under light illumination and induce bacteria death.Imidazole compounds have attracted much attention,due to a variety of biological activities,including anti-tumor and anti-bacteria.In this paper,we designedaseriesofImidazole-BODIPYderivatives2-（1H-imidazol-2-yl）vinyl-5,5-difluoro-1,9-dimethyl-10-（4-nitropheny-l）-5H-4l4,5l4-dipyrrolo[1,2-c:2’,1’-f][1,3,2]diazaborinine（BIN）and2-（1H-imidazol-2-yl）vinyl-5,5-difluoro-1,9-dimethyl-5H-4l4,5l4-dipyrrolo[1,2-c:2’,1’-f][1,3,2]diazaborinin-10-yl)aniline（NH₂-BIN）by using Knoevenagel method,and synthesized two light-activated nano-antibiotic composites（BIN-Zn and BIN-ZnO）and“sense and treat”fluorescent probe(NH₂-BIN Ps-Cu²⁺).In addition,we have studied the structure,photophysical properties and antibacterial activities of BODIPY-based composites and developed the structure-property relationships of antibacterial materials and the antibacterial mechanism.The main research contents are as follows:（1）A novel visible light-activated antibacterial complex（BIN-Zn）based on BIN ligand was obtained and characterized.BIN-Zn exhibits no obvious dark toxicity on E.coli and S.aureus,but shows strong antibacterial effect on E.coli and S.aureus with LED light（7 W）.MIC to the E.coli and S.aureus is about 8μg/m L and 4μg/m L,respectively.MBC to the the E.coli and S.aureus is about 10μg/m L and 6μg/m L.The study of antibacterial mechanism indicates that ¹O₂and·OH may be possibly responsible for the light-activated antibacterial activity of BIN-Zn.（2）We employ BIN as photosensitive ligand and Zn atoms in ZnO as metal centers to successfully construct a novel antibacterial material BIN-ZnO by coordination-driven self-assembly.BIN-ZnO exhibits extraordinary photo-induced antibacterial activation against E.coli and S.aureus in comparison to the reported ZnO under mild conditions.MIC is about 6μg/m L to the S.aureus and E.coli,and MBC to the S.aureus and E.coli is about 9μg/m L.The successful introduction of BIN decreases the band gap energy and enhances the light harvesting of BIN-ZnO.The study of antibacterial mechanism indicates that BIN-ZnO shows synergistic antibacterial effect owing to the improved Zn ions’release and reactive oxygen species（ROS）production under LED irradiation.（3）A novel fluorescent probe（NH₂-BIN Ps）was synthesized by Knoevenagel condensation and studied its responses to anions.It was found that copper ions can induce NH₂-BIN Ps fluorescence quenching,while E.coli can capture Cu²⁺to restore the fluorescence of the system.Therefore,NH₂-BIN Ps-Cu²⁺can be used as a fluorescent probe for detecting E.coli with a minimum detection limit of 1.04CFU/m L.NH₂-BIN Ps-Cu²⁺exhibits photo-induced antibacterial activity against E.coli.,which can completely inhibit the growth of E.coli after 2 h LED illumination（7W）.NH₂-BIN Ps-Cu²⁺may be a novel“sense and treat”fluorescent probe.