Synthesis And Application Of Near-infrared Heptamethine Indocyanine Fluorescent Probes For Hydrosulfide Ions

As a typical endogenous gasotransmitter,hydrogen sulfide?H₂S?was found to present an important effect on physiology and pathology regulation in cardiovascular,nervous,digestive and immune systems of human body,therefore,it's very important to detect H₂S/HS^-in physiology and pathology.Based on the outstanding advantages of near-infrared fluorescent probes in ion detection of biological and cellular environment,two fluorescent probes for HS^-detection were designed and synthesized based on near-infrared heptamethine indocyanine.Therein,probe 5 was chosen for further research as it has obvious detection capability.The absorption and fluorescence spectrum of probe 5 were recorded and investigated,it was found that the absorption and emission peaks are both in near-infrared region,which is beneficial to avoid the interference of background fluorescence from biological tissue.After treatment with HS^-,the absorption and fluorescence spectrum of probe 5 displayed rapid and dramatic response,which reached a plateau within 10 minutes.In addition,the solution color would also changed upon addition of HS^-,which makes it possible to recognize HS^-by naked eyes.The selectivity,responsiveness to HS^-concentration,and cytotoxicity of probe 5were investigated.The obtained results indicated that probe 5 has good selectivity and the fluorescence intensity can change along with HS^-concentration,and a good linearity between the fluorescence intensity and HS^-concentration in certain extent was established,the detection limit was calculated to be 0.33?M.Probe 5 doesn't have obvious toxicity in test concentration,so it can be used in organism properly.The interaction mechanism of probe 5 towards HS^-was speculated and confirmed:HS^-triggers the cleavage of the acrylate bond in probe 5 by nucleophilic attack,which result in the structure changes of probe 5,so that its absorption and fluorescence spectrum are changed and act as response signals.The application of probe 5 to HS^-detection in biological serum samples and cells imaging were studied,and the results showed that probe 5 can detect HS^-successfully even in complex biological serum samples without various interferences.Besides,it is observed that probe 5 has good cellular membrane permeability,which make s it available to detect HS^-in cell by cellular fluorescence imaging.