A highly selective and instantaneous upconversion fluorescent nanoprobe for ascorbic acid detection in biological samples

Ascorbic acid (AA) serves as a key coenzyme in many metabolic pathways. Enough daily AA supplements from different dietary sources are the only way for human to maintain their AA levels in body. Determination of AA content in different foods guides to build healthy diet, which is of great biomedical significance. Hence, developing a highly selective and instantaneous fluorescent nanoprobe for the detection of AA in biological samples is highly needed. Here we present a novel turn-on fluorescent nanoprobe using lanthanide-doped upconversion nanoparticles (UCNPs) and cobalt oxyhydroxide (CoOOH) nanoflakes for monitoring AA in fruit samples. In this nanosystem, the UCNPs can be adsorbed onto the CoOOH nanoflakes, leading to a remarkable fluorescence decrease through Förster resonance energy transfer. Furthermore, the AA could trigger the disassembly of the CoOOH to liberate the upconverted fluorescence. The UCNPs-based nanoprobe can provide an effective platform for highly selective and rapid detection of AA in biological samples.