In situ synthesis of fluorescent copper nanoclusters for rapid detection of ascorbic acid in biological samples

Ascorbic acid (AA) plays an important role in many physiological and biochemical processes. Herein, a novel, rapid and label-free fluorescence strategy was proposed to detect ascorbic acid based on the in situ formation of copper nanoclusters (CuNCs). When reducing ascorbic acid was present, the Cu(II) ions in 3-(N-morpholino) propanesulfonic acid (MOPS) buffer were transformed into CuNCs and showed high fluorescence. The excitation and emission peaks of CuNCs were 340 nm and 580 nm, respectively. The fluorescence intensity was proportional to the concentration of ascorbic acid. Under optimized conditions, the linear range of ascorbic acid detection is 50 to 1000 μM, and the detection limit is 41.94 μM. In addition, this method is successfully applied to the determination of ascorbic acid in real samples (serum samples and vitamin C tablets) and has shown satisfactory results. Besides the simple operation and good detection capability, the signal response of this method to ascorbic acid is fast and can reach maximum saturation in a few minutes. There is no background interference due to the in situ formation of the signal unit (CuNCs). Therefore, the proposed strategy has a strong potential to detect ascorbic acid in medical diagnosis and food safety due to its excellent analytical sensitivity and high selectivity.