Redox modulated fluorometric sensing of ascorbic acid by using a hybrid material composed of carbon dots and CoOOH nanosheets.

Carbon dots (CDs) were hydrothermally prepared from gelatin as the sole precursor. The CDs were hybridized with CoOOH nanosheets (NSs) to obtain a fluorescent probe (CD-CoOOH) for ascorbic acid (AA). The blue luminescence of the CDs, with excitation/emission maxima of 350/443 nm, is quenched by the NSs. If the NSs are reduced to Co2+ by addition of AA, the CD-CoOOH hybrid is disintegrated and fluorescence recovers. The hybrid nanoprobe has a linear response in the 0.8-12.5 μM and 12.5-690 μM AA concentration ranges and a 0.025 μM limit of detection. Compared to previously reported methods for detecting AA, this methods has a wider linear range and a lower detection limit. The nanoprobe was utilized to quantify AA in spiked human serum samples and gave satisfactory results. The strategy was also applied to the construction of an "AND" logic gate, which avoided perplexed material decorations and chemical tracking. Graphical abstract Scheme 1. Schematic illustrations of the preparation of CDs and of the working principle for determination of ascorbic acid (AA).