Synthesis Of Rhodamine/Fluorescein-Based Fluorescent Probes And Application In Thiols Detection

Small molecule biothiols have unique chemical reactivity and play a vital role in maintaining the stability of life systems,cysteine(Cys),homocysteine(Hcy)and glutathione(GSH)are representative molecules.High sensitivity and high selectivity detection of biothiol and its biological activity in physiology and pathology are of great significance for biochemical research and clinical diagnosis.The reactive organic molecular fluorescent probe has the advantages of in-situ detection,high sensitivity,fast detection speed,good selectivity,and has good application prospects in the fields of environmental analysis,cell staining and biological detection.Currently,in probes reported to detect small molecule biothiols,relatively few reversible fluorescent probes based on xanthene structures and disulfide cleavage thiols.Fluorescein and rhodamine derivatives belong to xanthene dyes,which have the advantages of high quantum yield,large molar absorption coefficient and good water solubility,the probes have been widely used in various fields such as ion detection and biological imaging.The main research objective of this paper is to design disulfide fluorescent probes FLDP-1,RHDP-1,RHDP-2 and RHDP-3 based on two fluorophores of fluorescein and rhodamine,and the corresponding fluorides,through the thiol-disulfide exchange reaction to achieve efficient,reversible labeling of cysteine residues on the surface of proteins.The quantum yield of the probe FLDP-1 dimer form is lower than that of the monomer form,which means that it can’t achieve fluorescence enhancement after reaction with the thiol.However,the quantum yield of the dimeric form of RHDP is much higher than the quantum yield of the monomer,which is consistent with our original design and can react with N-acetyl-L-cysteine to form rhodamine-cysteine mixture.This study offers the possibility of a novel reversible fluorescent probe for cysteine abeling,however the detection of cellular or in vitro biothiols needs further investigation in the future.