Investigation the interaction between protamine sulfate and CdTe quantum dots with spectroscopic techniques

The interaction between protamine sulfate and CdTe quantum dots (QDs) was investigated in detail by spectroscopic techniques. It was found that the fluorescence of QDs was quenched intensely by protamine sulfate. According to the results of lifetime measurements, temperature dependence, UV-Vis absorption spectra, calorimetric titration and zeta potential measurements, a combined dynamic and static quenching model was proposed. The binding force was also discussed and the process was found to be associated with electrostatic interaction. The results of this work indicated that the charge of protein has great effect on the emission of QDs. Moreover, it should contribute to the studies of interactions of QDs with proteins and promotes its application in biological systems.