Construction of dye-sensitized upconversion nanoparticles for application to an ultrasensitive ratiometric probe for R6G

As a frequently utilized fluorescent dye, R6G assumes a crucial role in biomedical imaging, environmental monitoring, and chemical sensing due to its distinctive optical characteristics. Nevertheless, its application has also brought along corresponding environmental issues, rendering the trace detection of R6G dye particularly significant. Herein, we present a novel and facile approach employing dye-sensitized lanthanide-doped nanocrystals that effectively addresses these limitations. The upconversion (UC) luminescence of these nanocrystals is significantly enhanced by two orders of magnitude under the sensitization of indocyanine green (ICG) dye molecules. Thus, we have established a solid foundation for a highly sensitive ratiometric fluorescence sensing system. Taking advantage of this property, we have developed a UC-based R6G dye trace probe with extremely high detection sensitivity, capable of resolving concentrations as low as 10^− 9 mol/L. We have comprehensively investigated the underlying mechanism of dye-sensitized UC luminescence, revealing key enhancements in the analytical performance of our probe. The substantial progress achieved in this study has far-reaching implications for applications in food safety, drug development, and environmental monitoring, and provides a promising direction for future research and technological innovation in the domain of trace detection of organic dyes.