Design,Synthesis And Sensing Properties Of Fluorescent Mercuric Probe For Biological Application

Mercury is a kind of heavy metal with severe physiological toxicity.It can easily enter the food chain by various pathways and accumulate in the body step by step.It is hard to be excreted through the metabolic function of the organism.Its long-lasting toxicity and high bioaccumulation are extremely destructive to environment and pose a serious risk to biological health.In recent years,with the frequent application of mercury in industrial production,the environmental pollution and the biological hazards caused by it have become increasingly serious.The research on the evaluation of biological toxicity of mercury also draws extensive attention.Therefore,it is of great theoretical significance and practical value to develop ahighly sensitive and highly selective detection method to detect Hg2+ content in water in real time,in situ,dynamically and specifically and also develop fluorescent probes which are suitable for fluorescence imaging of intracellular Hg2+.In this paper,we first synthesize the porphyrin-thiourea derivative(PT)as a reactive Hg2+fluorescence probe.Based on the thiophilicity of mercury,the Hg2+ can be detected by intramolecular desulfationgu,anylation reaction.It will generate a product which has a different structure from PT,thereby changing the photophysical properties of the attached porphyrin fluorescent chromophore molecule to achieve the Hg2+ detection.The results showed that PT had a fluorescence response towards Hg2+ in methanol solution with the detection limit as low as 2.4×10-8M.Besides,PT showed high selectivity toward Hg2+ and other metal ions showed no interference.In order to further expand the application scope of fluorescent probe molecules,we improved the water solubility and biocompatibility of probe molecules.We introduce sulfonic acid groups into porphyrin molecules,design and synthesize water-soluble probes PT1,PT2.We also discuss and compare the Hg2+ detection performances ofPT1,PT2 in aqueous environment.The results shows that PTi had good water solubility,and can achieve the sensitive detection of Hg2+ in pure water solutionwith a detection limit of 1.8×10-8M.The water solubility of PT2 is weaker than PTi,and the selectivity toward Hg2+ can be detected in the mixed solution of CH3OH/Tris-HNO3(1/1,v/v)with the detection limit of 1.9×10-9 M.MITT experiments show that both PTi and PT2 have low cytotoxicity and both can achieve the fluorescence imaging of Hg2+ detection in cells.PTi is further applied to the detection of Hg2+ in actual water samples.The recovery rate of the experiment is 98%?102%,indicating great accuracy of this method.