Highly Sensitive and Selective Fluorescent Probe for Ascorbic Acid with a Broad Detection Range through Dual-Quenching and Bimodal Action of Nitronyl-Nitroxide

A novel nitronyl-nitroxide derivative for highly sensitive and selective detection of ascorbic acid (AA) is reported. The probe showed 260-fold fluorescence turn-on and diminished electron spin resonance (ESR) signal upon AA addition. The probe could detect AA over a broad concentration range from 1 mu M to 2 mM and excellent selectivity over various antioxidants and acids through a combination of fluorescence and ESR responses, which originated from the dual reactiveness of dual-quenching group nitronyl-nitroxide. We successfully demonstrated practical application potential of the probe by preparing nanoparticles and sensor papers and determining AA concentration in real samples including vitamin drinks and orange juices.