Chiromagnetic Co(OH)2 nanoparticles with high asymmetry for electrochemical recognition and detection of ascorbic acid enantiomers

Abstract

L-ascorbic acid (L-AA) and its enantiomer D-isoascorbic acid (D-IAA) with similar physicochemical properties have been broadly used in healthcare, cosmetic, and food industries. However, L-AA shows much higher physiological activity than D-IAA in maintaining human health. Therefore, effective recognition and detection of L-AA and D-IAA is essential. Herein, chiromagnetic Co(OH)₂ nanoparticles with tunable asymmetry g-factors ranging from 0.012 to 0.053 are synthesized by the coordination of d- or L-aspartic acid and used to recognize L-AA and D-IAA by an electrochemical method. Chiral Co(OH)₂ catalysts have enantioselective electrochemical L-AA and D-IAA oxidation activities, and the oxidation of AA is easier to proceed on homochiral Co(OH)₂ catalyst due to a smaller oxidization barrier and the chirality-induced spin selectivity effect. Moreover, the asymmetry of the Co(OH)₂ catalyst strongly influences the oxidation of the homochiral AA reactant. According to the linear curves of oxidation current density versus AA concentration over the different chiral Co(OH)₂ catalysts, recognizing the chirality and concentration of AA can be easily achieved. This electrochemical AA oxidation method can recognize AA at the nM level and is sensitive to changes in AA concentration, providing good application prospects.