Interactions between CdTe quantum dots and plasma proteins: Kinetics, thermodynamics and molecular structure changes

Environmental particulate matter, especially ultrafine particles (< 100 nm in diameter), can damage the endothelium and favor cardiovascular disease in the general population. With the wide application of nanomaterials, exposure to nanoscale particles (nanoparticles) in the environment is increasing. Systematic study of the interaction of nanoparticles with plasma proteins is critically important for understanding the cardiovascular toxicity of nanomaterials. We combined kinetics and thermodynamics information from surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) and conformational data from fluorescence spectroscopy and circular dichroism (CD) to explore the binding mechanism between cadmium telluride quantum dots (CdTe QDs) and plasma proteins. Special attention was paid to the interaction between CdTe QDs and coagulation-related proteins and the effects of CdTe QDs on protein conformation. The results showed that the binding affinities of CdTe QDs and plasma proteins depend on the nature of the protein and follow the order of fibrinogen (FIB)> plasminogen (PLG) > thrombin (TM) > metallothionein-II (MT-II) > human serum albumin (HSA). The interaction was primarily attributed to hydrophobic forces and the spontaneity of the occurrence of the interaction, and the protein secondary structures of FIB and PLG were changed significantly. The information gained in this study might shed light on the potential toxicity of QDs to the cardiovascular system.