Systematic investigation of the toxicity interaction of ZnSe@ZnS QDs on BSA by spectroscopic and microcalorimetry techniques

Abstract

The interaction of ZnSe@ZnS quantum dots (QDs) and bovine serum albumin (BSA) was investigated by means of fluorescence (FL) spectrometry, circular dichroism (CD) spectra, and isothermal titration calorimetry (ITC). The fluorescence intensity of BSA decreased regularly with the increasing of QDs concentration. The decrease of BSA fluorescence intensity was proved to be a kind of static quenching. CD results show the helicity of BSA decreased from 38.04% to 26.51% with the addition of QDs, which suggests a stronger structural change that is related to a low degree of surface coverage. And also, both ion strength and pH value could affect the interaction between BSA and QDs, suggesting that both the static electronic attraction and H-bond contribute to the interaction between BSA and QDs. The thermodynamics of interaction between BSA and QDs were calculated from ITC data. Both enthalpy and entropy changes were favorable for the interaction in Tris-buffer, while only enthalpy change was favorable for the interaction in NaCl or HCl solution.

Keywords: Bovine serum albumin; Conformation change; Spectroscopic methods; Thermodynamics; ZnSe@ZnS quantum dots.