Design And Synthesis Of Near-infrared Rhodamine Fluorescent Probes And Their Detection Applications

Fluorescent probes have become one of the hot spots in the field of analytical chemistry and biology because of their advantages of high sensitivity,good selectivity,fast response and small damage to cells through optical signal detection methods.Among various types of fluorescent probes,organic small molecule fluorescent probes have been receiving continuous attention from researchers because of their unique properties,such as high molar extinction coefficient and fluorescence quantum yield,easy adjustment of spectral range,easy synthesis and functionalization of molecular structure,and good biocompatibility.The first work in this paper is to design and construct a novel colorimetric and ratiometric near-infrared fluorescent probe QR for the detection of mercury ions based on quinoline fusion conjugated rhodamine dye.Due to the quinoline structure in the probe molecule,QR shows strong fluorescence emission in the visible region,and when the specific reaction between QR and mercury ions,the spironolactam structure is looped,the fluorescence in the visible region is weakened,and the fluorescence in the near-infrared region is significantly increased,resulting in an obvious ratio two-channel fluorescence response.QR has high selectivity and sensitivity for Hg²⁺（limit of detection:23 nM）.Based on these spectral characteristics,probe QR can be used not only to detect Hg²⁺in tap samples,but more importantly,to monitor Hg²⁺changes in live cells with dual-channel ratio fluorescence imaging.In view of the problem of fluorescence quenching of NIR-Ⅱ organic dyes in water,the second work of this paper develops NIR-Ⅱ dyes with aggregation-induced luminescence（AIE）properties.Using Aza-BODIPY as the dye skeleton,and introducing triphenylamine（TPE）and tetraaryl vinyl（TPA）as donor groups,the NIR-Ⅱ dye JF with AIE properties was designed and synthesized.The dye JF has fluorescence emission in the NIR-Ⅱ region and has obvious aggregation-induced luminescence properties.By wrapping DSPE-PEG₂₀₀₀,the dye nanomaterials JF-NPs with good biocompatibility were obtained,which had high molar extinction absorption of 4.66×10⁴ M^-1cm^-1 and fluorescence quantum yield of 8.4%,as well as high photostability and chemical stability.Finally,the nanomaterial JF-NPs were injected into mice through the tail vein.Under the same conditions,the fluorescence imaging sign background radio（SBR）of the material in blood vessels was 1.94 times that of ICG.So JF-NPs could be used as an effective tool for NIR-Ⅱ in vivo imaging research.