Dual-emission ratiometric fluorescence detection of aspirin in human saliva: Onsite naked-eye detection and high stability

In this paper, a highly stable ratiometric fluorescence probe based on dual-emission quantum dots (QDs) was designed for the visual detection of aspirin. The probe was composed of two differently colored CdTe QDs, in which red-emitting QDs embedded in SiO₂ (r-QDs@SiO₂) acted as the reference signal and green-emitting QDs (g-QDs) covalently anchored on the surface of r-QDs@SiO₂ served as the response signal. The fluorescence of r-QDs@SiO₂ remained constant, whereas the fluorescence of g-QDs was quenched by the addition of aspirin. As a result, continuous color changes in the dual-emission fluorescence probe were observed. Under optimum conditions, the as-prepared dual-emission fluorescence probe was used for the determination of aspirin in a concentration range of 6.0-45 μmol L^-1 with a detection limit of 0.20 μmol L^-1. Furthermore, the present method was successfully applied in the detection of aspirin in real samples with a relatively high stability for about ten days.