Photo-controlled fluorescent switches based on Si@ZnO quantum dots and diarylethenes for bioimaging and anti-counterfeiting

Abstract

The regulation of fluorescence emission of quantum dots by photochromic molecules has received considerable attention. However, the effects of the structure of photochromic compounds on their properties still need to be further investigated. Herein, two photo-controlled fluorescent switches were constructed with Si@ZnO quantum dots and two photochromic diarylethenes, respectively. In these two fluorescent switches, the diarylethenes could be transformed between open-ring state and closed-ring state upon irradiation with UV/vis lights, resulting in the fluorescence of the Si@ZnO switched between “ON” and “OFF”. The fluorescence modulation efficiencies of the two fluorescent switches were measured to be 91.5% and 88.7%, respectively. The effects of the structure of diarylethenes on the light response times, fluorescence lifetimes, and fatigue resistance were also studied. The mechanism of the fluorescent switching could be ascribed to the fluorescence resonance energy transfer (FRET) with Si@ZnO quantum dots as energy donors and diarylethenes in closed-ring state as energy acceptors. Furthermore, the prepared fluorescent switches were applied in bioimaging and anti-counterfeiting successfully.