One-pot synthesis of highly luminescent N-acetyl-L-cysteine-capped CdTe quantum dots and their size effect on the detection of glutathione

Aqueous N-acetyl-L-cysteine (NAC)-capped CdTe quantum dots (QDs) are prepared in one step by using sodium tellurite as a tellurium source and sodium borohydride as a reductant. The fluorescence (FL) emissions of the QDs are tunable between 514 and 753 nm. The effects of NAC/Cd, Cd/Te molar ratios, and pH values on the photoluminescence quantum yield (PLQY) of the QDs have been systematically studied. They display a high PLQY of up to 52.83%, with uniform narrow-size distributions. Furthermore, the obtained green- and red-emissive CdTe QDs are applied to explore the impact of QD size on the FL response toward glutathione (GSH) by a “turn-on” strategy. The results imply that the large-sized CdTe QDs with red FL are more suitable for detecting GSH than the small-sized QDs with green FL. The possible mechanism is also investigated.