Characterization of the interaction between mercaptoethylamine capped CdTe quantum dots with human serum albumin and its analytical application

Abstract

CdTe quantum dots (QDs) were synthesized in aqueous solution using 2-mercaptoethylamine hydrochloride (CA) as stabilizing agents. The interaction between CA-CdTe QDs with human serum albumin (HSA) was investigated by ultraviolet–visible (UV–vis) absorption, circular dichroism (CD), fluorescence and resonance Rayleigh scattering (RRS) spectroscopy. CD spectra revealed that the conformation and microenvironment of HSA were changed in the presence of CA-CdTe QDs. CA-CdTe QDs could strongly quench the intrinsic fluorescence of HSA by static quenching. The electrostatic interaction plays a major role in stabilizing the complex. The binding site number n and apparent binding constant K, corresponding thermodynamic parameters Δ G°, Δ H° and Δ S° at different temperatures were calculated. The interaction between CA-CdTe QDs and HSA led to the remarkable enhancement of RRS and the enchantments were in proportional to the concentration of HSA in the range 0.05 × 10 −7 to 4.0 × 10 −7 mol L −1 and a detection limit of 4.2 × 10 −9 mol L −1. Based on this, RRS methods to determinate HSA were developed. The influences of factors on the interaction between HSA with CA-CdTe QDs and some foreign substances were all examined, which showed that the method had a good sensitivity and selectivity. In addition, the reasons for the enhancement of RRS were investigated.