Gold nanoclusters reversible switches based on aluminum ions-triggered for detection of pyrophosphate and acid phosphatase activity

Abstract

Gold nanoclusters (AuNCs) were synthesized using glutathione (GSH) as a reducing agent and stabilizer. The aluminum ions could trigger the aggregation of AuNCs, causing a significant fluorescence, owing to the more vital coordination between Al3+ and pyrophosphate (PPi), AuNCs-Al3+ was disaggregated with the addition of PPi, resulting in a considerable fluorescence quench of the system. When acid phosphatase (ACP) was present, PPi was consumed by ACP, which inhibited the disaggregation of AuNCs. Based on the principle of Al3+ and PPi inducing aggregation-disaggregation of AuNCs accompanied by fluorescence enhancement-quenching, a novel method was established for fluorescence "turn-on-off-on" detection of PPi and ACP activity. The PPi detection limit was determined to be 0.1 µM in the linear range of 0.3-100 µM (R2 = 0.9995). The ACP detection limit was determined to be 4.16 U L−1 in the linear range of 15.0-80.0 U L−1 (R2 = 0.9970). The proposed GSH-AuNCs biosensor exhibits excellent sensing efficiency and has been introduced to determine PPi and ACP in real samples with satisfactory results.