Facile synthesis of Eu-doped niobium carbide MXene quantum dots for parallel detection of hypoxanthine and fluoxetine via fluorescence quenching and enhancement mechanisms.

A hydrothermal synthetic method is established to produce blue fluorescent Eu-doped niobium carbide MXene quantum dots (Eu-NbC MQDs). The synthesized Eu-NbC MQDs demonstrated a quantum yield of 20.61% and a maximum emission intensity at 405 nm. The as-prepared Eu-NbC MQDs acted as a sensor for the rapid and sensitive detection of hypoxanthine through fluorescence quenching, and of fluoxetine through fluorescence enhancement mechanisms. The emission peak of Eu-NbC MQDs at 405 nm exhibited a linear response for hypoxanthine and fluoxetine in the ranges of 0.5-25 µM and 0.125-2.5 µM, with detection limits of 15.0 and 3.7 nM, respectively. The newly developed probe was effectively used for the selective detection of hypoxanthine and fluoxetine in biofluids and pharmaceutical samples. Remarkably, the Eu-NbC MQDs exhibited minimal cytotoxicity towards A549 lung cancer cells and showed great potential as imaging agent for imaging of Saccharomyces cerevisiae cells.