Influence of Chiral-Related Selective Adsorbed Oxygen on the Fluorescence Interaction between CdTe Quantum Dots and Folic Acid

The chirality of quantum dots (QDs) has been extensively studied in recent years and shows potential applications in optics and biology. Yet, the influence of chirality on the fluorescence properties of QDs is still not fully understood. In this work, the chiral-dependent fluorescence quenching effect of l-Cys-CdTe and d-Cys-CdTe QDs was systematically studied by the precise titration of folic acid in the 10–7 order. The fluorescence intensities for both samples show a linear relationship with FA concentration, indicating the static quenching effect. A slight blue shift is observed only for l-Cys-CdTe QDs after precise titration of the folic acid concentration in the 10–7 order, while the emission peak for d-Cys-CdTe QDs remains unchanged at the same concentration. We speculate that the chiral-dependent absorbed oxygen may be responsible for such a phenomenon, which is verified by X-ray photoelectron spectroscopy and density functional theory calculations.