Ce4+/Ce3+as the switch of AIE-copper nanoclusters for highly selective detection of ascorbic acid in soft drinks

An ultrasimple turn-on sensor for indirectly detecting ascorbic acid (AA) was prepared using N-acetyl-L-cysteine stabilized copper nanoclusters (NAC-CuNCs) via the AIE (aggregation-induced emission) effect controlled by Ce4+/Ce3+ redox reaction. This sensor fully utilizes the different properties of Ce4+ and Ce3+. Non-emissive NAC-CuNCs were synthesized by a facile reduction method. NAC-CuNCs easily aggregate in the presence of Ce3+ due to AIE, resulting in fluorescence enhancement. However, this phenomenon cannot be observed in the presence of Ce4+. Ce4+ possesses strong oxidizing ability and produces Ce3+ by reacting with AA via a redox reaction, followed by switching on the luminescence of NAC-CuNCs. Moreover, the fluorescence intensity (FI) of NAC-CuNCs increases with the concentration of AA in the range of 4-60 & mu;M, with the limit of detection (LOD) as low as 0.26 & mu;M. This probe with excellent sensitivity and selectivity was successfully used in the determination of AA in soft drinks.

Automated summary

An ultrasimple turn-on sensor for indirectly detecting ascorbic acid (AA) was developed using N-acetyl-L-cysteine stabilized copper nanoclusters (NAC-CuNCs) via the aggregation-induced emission (AIE) effect controlled by Ce4+/Ce3+ redox reaction. The sensor takes advantage of the different properties of Ce4+ and Ce3+. Non-emissive NAC-CuNCs were synthesized and easily aggregate in the presence of Ce3+, resulting in fluorescence enhancement. Ce4+ reacts with AA via a redox reaction, producing Ce3+ and switching on the luminescence of NAC-CuNCs. The probe exhibited excellent sensitivity and selectivity, with a low limit of detection, and was successfully applied to detect AA in soft drinks.