New strategy for the evaluation of CdTe quantum dot toxicity targeted to bovine serum albumin.

The biological toxicity of CdTe quantum dots (QDs) to bovine serum albumin (BSA) has been investigated mainly by fluorescence spectra, UV-vis absorption spectra and circular dichroism (CD) under simulative physiological conditions. Fluorescence data revealed that the quenching mechanism of BSA by CdTe QDs was a static quenching process and the binding constant is 6.05x10(3) and the number of binding sites is 0.7938. The thermodynamic parameters (DeltaH=-62.33 kJ mol(-1), DeltaG=-21.21 kJ mol(-1), and DeltaS=-140.3 J mol(-1) s(-1)) indicate that hydrogen bonds and van der Waals forces between the protein and the QDs are the main binding forces stabilizing the complex. In addition, UV-vis and CD results showed that the addition of CdTe QDs changed the conformation of BSA.