Design,Synthesis And Biological Application Of Porphyin-based Zn²⁺ Fluorescent Sensor

Zinc is widely distributed in nature and living organisms.In the human body,zinc ion(Zn²⁺)is the second most abundant trace element only behind iron,and plays an irreplaceable role in a series of physiological metabolic regulation processes,like gene expression,cell metabolism,signaling and immune response.Fluctuations of Zn²⁺in tissues usually indicate change in its function,and abnormal of Zn²⁺concentration may lead to pathological reaction.Therefore,the detection,especially the real-time monitoring of Zn²⁺in cells,and in living organisms have important biological significance.In this work,a water-soluble porphyrin-pyridine derivative(o-SP7)was synthesized.The unique coordination property of Zn²⁺with N atom,that enabling o-SP7 to trap Zn²⁺into a penta-coordinated square-pyramidal geometry via perpendicular(axial)ligation,resulting in a ratiometric change in the spectral propertie of o-SP7,which achieves the purpose of detecting trace Zn²⁺.Further experiments such as spectral titration,nuclear magnetic resonance analysis,and control molecules confirmed the proposed coordination mechanism.The unique axial coordination mode of o-SP7 with Zn²⁺enables it free of interference from other cations.It can realize the unique detection of Zn²⁺in aqueous solution,and the detection limit was low to 3.11×10^-8 M.The MTT method was used to investigate the cytotoxicity of o-SP7 on A549 cells,HUVEC cells,and 293T cells.The results showed that o-SP7 had no obvious toxicity on these three cell lines.Even the concentration was high to 0.1 mmol/L,the 4 h survival rates of all cells are more than 80%.With o-SP7 incubation,exogenous Zn²⁺imaging can be realized in three kinds of cells.The endogenous Zn²⁺distribution on zebrafish larva development can be visualized by laser scanning confocal microscope(LSCM).This method provides useful insights for an in-depth understanding of the role of Zn²⁺in cell life activities,and provides novel ideas and approaches for the detection of other metal ions in the body.