Design,Synthesis And Application Of Long Wavelength Fluorescent Probe

Biological sulfhydryl compounds such as cysteine,homocysteine and glutathione,as well as one of the most important reactive oxygen species in cells--hydrogen peroxide?H₂O₂?,play an extremely important role in cell physiology and pathology.Viscosity,as a signal substance in cells,is involved in the transmission of chemical signals in cells.Prevention and early diagnosis of these active substances are critical.The following deficiencies in the detection of these biomolecules using fluorescent probes have been reported:?1?Emission wavelengths at shorter wavelengths?<600 nm?,limiting the detection in biological samples.?2?The existence of fluorescent probes for distinguishing detection of Cys?Hcy and GSH required multiple excitation wavelengths.?3?For H₂O₂and viscosity simultaneous detection of fluorescent probes not very mature.A fluorescent probe with long wavelength emission is proposed to be used for biomolecular detection by regulating the molecular structure of the probe.The main contents are as follows:1.The fluorophores?F1?with long-wavelength emission were obtained by coupling 4-dimethyl-2,6-dimethyl-4H-pyran?DCM?with 2,4-diethyl salicylic aldehyde,and further reacted with the recognition group-2,4-dinitrobenzenesulfonyl chloride?DNBS?to synthesize a fluorescent Probe 1.Based on the fluorescence-on behavior of the Probe 1,the selective detection of sulfhydryl compounds at long wavelength was realized.2.Fluorescent Probe 2 was obtained by reacting the fluorophore F1 with7-nitro-1,2,3-benzoxazole?NBD?.The Probe undergone a nucleophilic substitution process with Cys/Hcy,and the fluorophore F1,NBD-SR₁and NBD-SR₂were released?SR₁was Cys,SR₂was Hcy?,with fluorescence emission at 565 nm and 628 nm were formed by intramolecular rearrangement reaction.There was no intramolecular rearrangement reaction after GSH reacted with the probe because of the intermolecular internal resistance.The distinguishing detection of Cys/Hcy and GSH was realized according to this principle3.The synthesis of Probe 3 was based on the binding of benzothiazole to conjugated electron receptors to form?bond conjugation,there was a distorted intramolecular charge transfer process,with the probe no fluorescence.The vibration relaxation was suppressed as the solution viscosity increased and still retained a strong intramolecular charge transfer?ICT?from the benzothiazole group to the pyridine ring with strong fluorescence with the strong emission at 680 nm.The reaction with the H₂O₂by the 1,4-elimination reaction,the results had the strong fluorescence emission at 590 nm.Based on the above principle,Probe 3 can achieve a dual wavelength response to viscosity and H₂O₂.In addition,the probe was successfully applied to cell fluorescence imaging.