荧光与表面张力法研究牛血清白蛋白与长链咪唑类离子液体的相互作用

he binding of long-chain imidazolium ionic liquid (IL), 1-tetradecyl-3-methylimidazolium bromide (C14mimBr) to bovine serum albumin (BSA) were investigated by fluorescence spectra and surface tension. Fluorescence spectra show that tryptophan (Trp) residues, one of the intrinsic fluorophores in BSA, are buried to a hydrophobic microenvironment with the addition of C14mimBr. The addition of C14mimBr induces denaturation of BSA. Moreover, the fluorescence quenching mechanism was determined to be static quenching. The equilibrium constant (K) and the number of binding sites (n) were calculated based on the results of fluorescence measurement. According to the surface tension plots, the critical aggregation concentration (CAC) and critical micelle concentration (CMC) under different BSA concentrations at various temperatures were investigated. The surface tension indicates that C14mimBr binds to BSA through electrostatic attraction at low concentration of C14mimBr (below CMC) and through hydrophobic interaction at high concentration of C14mimBr (above CMC). Additionally, thermodynamic parameters of micelle formation were determined. This study provides an understanding of the binding of C14mimBr to BSA.