Cyanine-based Near-infrared Fluoride Ion Probes:Synthesis And The Application

Fluoride ion is the smallest anion in nature and one of the most important anions.It plays an important role in industrial production,medicine,biology and other fields.Fluoride ion is also one of the essential trace elements in the human body.Studies have shown that imbalance of fluoride ion concentration in living organisms can cause a variety of diseases.Therefore,accurate measurement of fluoride ions in living organisms is of great significance in biomedicine and the like.Compared with traditional fluoride ion detection methods,the fluorescent probe method has the advantages of high sensitivity,good selectivity,and good biocompatibility.The near-infrared dyes have the advantages of strong penetrating power and little interference from background light.The absorption and fluorescence emission of the cyanine dye QCy7 are in the near-infrared region,which have obvious advantages in biological imaging.In this paper,three fluorescent probes were designed by using cyanine dye QCy7 as fluorophore:QCy7-TBS,QCy7-TBDPS and QCy7-TiPs.Through selectivity and anti-interference tests,we found that all three probes respond specifically to fluoride ion,with only a weak response to other ions.Concentration titration tests showed that quantitative detection of fluoride ion can be achieved separately in the range of 20-100?mol,60-200?mol and 80-240?mol.The time response tests showed that all three probes responded quickly to fluoride ion,and the probe QCy7-TBS responded fastest that reached equilibrium in 20minutes.Through pH stability and cytotoxicity tests,we found that the probes emited stable fluorescence in the pH range of the organism and was nontoxic to cells.Based on the rapid response of such probes to fluoride ion in vitro and low toxicity to cells,we tested the imaging of fluoride ion in cells and mice by QCy7-TBS.Although imaging experiments in cells had not yielded the desired results,tests in mice had shown that the probe can effectively detected fluoride ion in living organisms,reflecting the potential of such probes in biomedical applications value.Next,we will continue to study the imaging effect of this type of probe on fluoride ion in cells in order to obtain greater application value.Secondly,we used a hemi-cyanine dye containing coumarin and quinoline as the fluorophore,p-hydroxybenzyl bromide as the linker,and tert-butyldiphenylchlorosilane as the reaction site to synthesize the probe Mito-PF.The vitro tests showed that the probe had a specific response to fluoride ion,good selectivity,high sensitivity,and excellent anti-interference ability.Cytotoxicity experiments showed that the probe Mito-PF had little cytotoxicity and was capable of performing cell biological imaging.Finally,the probe Mito-PF successfully detected different concentrations of fluoride ion in HeLa cells,indicating its potential biomedical application value.In addition,we found that the probe Mito-PF itself had very weak fluorescence in a highly polar solvent,but when the polarity of the solvent was reduced,it would produce fluorescence at 710 nm.This test results indicated that the probe had the ability to detect solvent polarity and may be used to detect polarity in cells.In this paper,two kinds of fluorescent probes were designed based on interrupting the silicon-oxygen bond by fluoride ion,and the molecular structure was confirmed by nuclear magnetic resonance(¹H NMR,¹³C NMR)and spectrometry?HRMS?.Afterwards,we performed UV and fluorescence analysis on the two types of probes,and finally applied the two types of probes to mouse and cell tests.The results show that the two types of probes have good imaging effects to fluoride ion,and can detect fluoride ions in the environment and organisms,which has potential application value.The successful determination of fluoride ion in cells and mice by both types of probes indicates that the probes have potential application value.