Copper nanoclusters reversible switches based on ions-triggered for detection of inorganic pyrophosphatase activity

[Display omitted] •Fluorescence reversible switch was designed based on CuNCs aggregation or disaggregation triggered by Al3+ or PPi.•Reversible switch was applied for detection of PPase activity based on the fluorescence "turn-on".•The method was conveniently used to detect positive samples with satisfactory results. In this work, copper nanoclusters (CuNCs) were synthesized via a one-step method using glutathione as the reducing agent and stabilizer, then characterized by means of various methods. The prepared CuNCs with the average diameter of 2.1 nm had excitation and emission wavelengths at 360 and 615 nm. Further, it was found that Al3+ could trigger the aggregation of CuNCs causing a remarkable fluorescence enhancement of the system. However, owing to the stronger coordination between Al3+ and pyrophosphate (PPi), CuNCs/Al3+ was disaggregated with the addition of PPi, resulting in a significant fluorescence quench of system. When PPase was present, PPi was consumed by PPase, which inhibited the disaggregation of CuNCs. Based on the principle of Al3+ and PPi inducing aggregation/disaggregation of CuNCs accompanied by fluorescence enhancement/quenching, a novel method was established for fluorescence "turn-on-off-on" detection of PPase activity. The detection limit of PPase was determined to be 1.3 mU mL−1 in the linear range of 3.0–40.0 mU mL−1. The established method was used to detect the positive samples of rat serum with satisfactory spiked recoveries, and applied for the screening of inhibitors.