The specific binding of a new 1,2,3-triazole to three blood proteins and it's appended rhodamine complex for selective detection of Hg2.

A synthesized compound, ethyl 2,5-diphenyl-2H-1,2,3-triazole-4- carboxylate (EDTC) was investigated on its physiochemical parameters and structural properties by using the quantum-chemical method. The results on the theoretical spectrum of EDTC were line with experimental fluorescence and absorption spectrum in large degree. Then EDTC was successfully synthesized to a novel rhodamine-based fluorescent probe (REDTC), which showed a distinct fluorescence enhancement upon the presence of Hg2+ in dimethyl formamide-water (DMF-H2O) buffer solution (pH 7.4). Meanwhile, the triazole appended colorless compound turns to pink upon complex formation with Hg2+ ions as 1:2 molar ratios and enables naked-eye detection. The chromogenic mechanism was determined by using spectroscopic measurements and TD DFT calculation. The fluorescence imaging experiments of Hg2+ in HeLa cell revealed that the probe REDTC could be labeled and it could be used in biological systems. Also, the intermediate EDTC was developed as a sensitive fluorescent probe for specific studies on the interactions to three kinds of blood proteins including human serum albumin (HSA), human immunoglobulin (HIg) and bovine hemoglobin (BHb) by using a series of spectroscopic methods and molecular docking under the simulative physiological conditions. The interactions between EDTC and these proteins led to the distinct fluorescence enhancement. The thermodynamic measured results further suggested that hydrophobic forces play a dominating role in stabilizing the complexes, which are in correspondence with the results from molecular docking. The UV-visible, synchronous, and three-dimensional (3D) fluorescence measurements demonstrated that EDTC influences the conformational of proteins and the microenvironment surrounding HSA, HIg, or BHb in aqueous solution.