Synthesis of CdSe quantum dots using selenium dioxide as selenium source and its interaction with pepsin

A novel method has been developed for the synthesis of thioglycolic acid (TGA)-capped CdSe quantum dots (QDs) in an aqueous medium when selenium dioxide worked as a selenium source and sodium borohydride acted as a reductant. The interaction between CdSe QDs and pepsin was investigated by fluorescence spectroscopy. It was proved that the fluorescence quenching of pepsin by CdSe QDs was mainly a result of the formation of CdSe–pepsin complex. Based on the fluorescence quenching results, the Stern–Volmer quenching constant (Ksv), binding constant (KA) and binding sites (n) were calculated. According to the Foster's non-radiative energy transfer theory, the binding distance (r) between pepsin and CdSe QDs was obtained. The influence of CdSe QDs on the conformation of pepsin has been analyzed by synchronous fluorescence spectra, which provided that the secondary structure of pepsin has been changed by the interaction of CdSe QDs with pepsin.

Graphical abstractCdSe QDs were synthesized in aqueous solution by using SeO2 as selenium. The interaction of CdSe QDs with pepsin was investigated. With the concentration of CdSe QDs increased, the fluorescence intensity of pepsin decreased gradually, but the emission wavelength almost has no change, confirming the local interaction between pepsin and QDs.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel and simple technology for preparing CdSe QDs using SeO2 as selenium source has been developed. ► The interaction of CdSe QDs with pepsin was investigated by spectroscopic methods. ► The Stern–Volmer quenching constant (Ksv), binding constant (KA) and binding sites (n) of the binding process between CdSe QDs and pepsin were calculated.