Highly fluorescent Ti3C2 MXene quantum dots for macrophage labeling and Cu2+ ion sensing

Abstract

Quantum dots, derived from two-dimensional (2D) materials, have shown promise in bioimaging, sensing and photothermal applications, and in white light emitting devices (WLEDs). Herein, nitrogen and phosphorus functionalized Ti₃C₂ MXene based quantum dots (N,P-MQDs) were successfully prepared through a top-bottom hydrothermal method. This type of photoluminescent quantum dots has realized green fluorescence for the first time at around 560 nm with a photoluminescence quantum yield (PLQY) of 20.1%, the highest ever reported; meanwhile, it also exhibits excellent photostability and pH resistance capacities. Comprehensive characterization and well-resolved density functional theory (DFT) calculation were implemented to determine the mechanism of fluorescence shift and enhancement. Furthermore, the N,P-MQDs have been proved to efficiently act as fluorescent probes for macrophage labeling. In addition, the high sensitivity of the N,P-MQDs toward Cu²⁺ ions made them a low cost, sensitive, environment-friendly, and label-free fluorescence platform for Cu²⁺ detection. The outstanding performance of Ti₃C₂ MXene based quantum dots has demonstrated their great potential to be used as promising fluorescent probes in the fields of biological imaging, optical sensing, photoelectric conversion, etc.