[Study on the synchronous interactions between different thiol-capped CdTe quantum dots and BSA].
The modifier of quantum dots plays an important role in synthesis and nature of quantum dots, however the effect on the interaction between quantum dots and protein is not very clear until up to now. In the present paper, the interactions of CdTe quantum dots with bovine serum album (BSA) were studied by spectroscopy methods including ultraviolet-visible absorption spectrometry (UV-Vis), fluorescence spectrometry (FL) and infrared spectrometry (IR). The CdTe quantum dots were modified by three different thiol-complex including thioglycolic acid, L-cysteine and glutathione, i. e. thioglycolic acid capped CdTe quantum dots (CdTe(T)), L-cysteine capped CdTe quantum dots (CdTe(L)) and glutathione capped CdTe quantum dots (CdTe(G)) respectively. The quenching constant K(sv) and corresponding thermodynamic parameters, such as enthalpy change (deltaH(theta)), entropy change (deltaS(theta)), Gibbs free energy change (deltaG(theta)), were calculated according to Stern-Volmer equations. The results showed that CdTe(T), CdTe(L) and CdTe(G) all have a strong ability of quenching the fluorescence of bovine serum albumin, and the interactions of the three types of thiol-capped CdTe quantum dots with BSA were static quenching process. The quenching constant of K(sv)(TGA) is similar to K(sv)(GSH), which is much less than K(sv)(L-Cys). The binding forces of CdTe(T) and CdTe(L) with the BSA were the main contributions from hydrophobic force according to the thermodynamic parameters (deltaH(theta) > 0, deltaS(theta) > 0 and deltaG(theta) < 0), while the binding forces of CdTe(G) with BSA were composed of both hydrogen bonding force and hydrophobic force according to the thermodynamic parameters(deltaH(theta) < 0, deltaS(theta) > 0 and deltaG(theta) < 0). It was found that different functional group and molecular volume size of thiol surface modified reagent played an important role in the interactions between CdTe QDs and BSA.
Ma
Jin-Jie
JJ
State Key Laboratory of Agricultural Microbiology, College of Science, Huazhong Agricultural University, Wuhan 430070, China. majinjie2001@webmail.hzau.edu.cn
Liang
Jian-Gong
JG
Han
He-You
HY