Intracellular redox potential-driven live-cell synthesis of CdSe quantum dots in Staphylococcus aureus

Biosynthesized semiconductor quantum dots (QDs) have bright fluorescence, adjustable particle sizes, and environmental friendliness, endowing them with convenience and potential for biological applications. Due to the unclear mechanism of the cellular environment on the live-cell synthesis of QDs, it is still difficult to regulate their optical properties. Here, the critical role of the intracellular redox environment in regulating the fluorescence properties of biosynthesized CdSe QDs in Staphylococcus aureus ( S. aureus ) has been elucidated. The glutathione peroxidase (GPx) activity directly affects the intracellular H 2 O 2 produced in the SeO 3 2− reduction, which further manipulates the glutathione redox cycle to determine the content of low-valence Se-intermediates. As a result, the fluorescence intensity of the synthesized CdSe QDs increases by 60% in the GPx overexpressed cells. The cellular redox potential that is controlled by the GSH redox cycle provides the driving force for the reduction of SeO 3 2− , facilitating the synthesis of CdSe QDs in S. aureus cells. The proposed mechanism of the cellular redox state provides a new perspective for regulating the synthesis of semiconductor nanomaterials in live cells.