A nanoclay-based magnetic/fluorometric bimodal strategy for ascorbic acid detection

Ascorbic acid (AA) plays an essential role in biochemical processes, as a scavenger for preventing oxidative damage. Although various optical measurement strategies for AA detection have been developed, there is an increasing demand for a multi-modal sensor to obtain detailed information. Herein, we propose a facile ion-exchange/coordination strategy for the preparation of a magnetic resonance (MR)/fluorescence nanohybrid by using laponite (Lap) as a matrix and Eu(DPA)(3)/Gd(DPA)(3) (DPA = Pyridine-2, 6-dicarboxylic acid) as a bimodal signal source. This nanohybrid was observed to have a higher MR response than Gd DPA, because Gd DPA was coordinated with Lap to affect proton relaxation parameters, while excellent Eu DPA fluorescence remained. Moreover, potential applications of the nanohybrid had been extended to transparent films and MR/fluorescent inks. Interestingly, the MR/fluorescence of this nanohybrid was simultaneously suppressed by AA. We found that this decrease was attributed to a synergistic effect of acidity and redox. The MR/fluorescence bimodal detection of Eu(DPA)(3)/Gd(DPA)(3)@Lap makes it as a potential biological probe for clinical applications and commercialization because of its simple preparation procedure, excellent MR/fluorescence properties, high sensitivity, and high selectivity. (C) 2017 Elsevier B.V. All rights reserved.