A Portable Sensing Platform Using an Upconversion-Based Nanosensor for Visual Quantitative Monitoring of Mesna

Mesna is an important regional antidote for protecting the urinary system of chemotherapy patients, which requires monitoring its level in real time to ensure the curative effect. The fluorescence method is a powerful tool in real-time detection with the advantages of fast response and visualization. However, the background interference limits its application in biological sensing. Here, we developed a portable sensing platform using an upconversion-based nanosensor for visual quantitative monitoring of mesna in real-time/on-site conditions. The nanosensor was constructed by upconversion nanoparticles (UCNPs) and ethyl violet (EV), in which the UCNPs emitted red and green light, while EV quenched the green light due to the inner filter effect (IFE). The reaction of mesna with EV caused its fading and broke the IFE process, leading to the recovery of green light. By the fluorescence and colorimetric chromaticity variations, the nanosensor achieved a dual-readout detection for mesna with low limits of detection (LODs) of 26 and 48 nM, respectively. Furthermore, a highly compatible sensing platform was fabricated for facile determination of mesna with an LOD of 56 nM, realizing visual quantitative monitoring of the mesna level to ensure the curative effect and providing a new strategy for point-of-care testing of drugs in clinical settings.