Multi-spectroscopic Study on the Interaction between CdTe Quantum Dots and Bovine Serum Albumin

The interaction between CdTe quantum dots (QDs) and bovine serum albumin (BSA) was systematically investigated by fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy under physiological conditions. The experimental results showed that the fluorescence of BSA could be quenched by CdTe QDs with a static quenching mechanism, indicating that CdTe QDs could react with BSA. The quenching constants according to the modified Stern-Volmer equation were obtained as 1.710 x 10(6), 1.291 x 10(6) and 1.010 x 10(6) L.mol(-1) at 298, 304, and 310 K, respectively. Delta H, Delta S and Delta G for CdTe QDs-BSA system were calculated to be -33.68 kJ.mol(-1), 6.254 J.mol(-1).K-1 and -35.54 kJ.mol(-1) (298 K), respectively, showing that electrostatic interaction in the system played a major role. According to Forster theory, the distance between Trp-214 in BSA and CdTe QDs was given as 2.18 nm. The UV-vis, synchronous fluorescence and CD spectra confirmed further that the conformations of BSA after addition of CdTe QDs have been changed.