Zinc ion-triggered aggregation induced emission enhancement of dual ligand co-functionalized gold nanoclusters based novel fluorescent nanoswitch for multi-component detection

Highlights: • Zinc ion-triggered aggregation induced emission enhancement (AIEE) fluorescence "on-off-on" nanoswitch was fabricated. • The proposed nanoswitch provide a low detection limit for inorganic pyrophosphate and inorganic pyrophosphatase. • The proposed nanoswitch could be applied for monitoring inorganic pyrophosphatase activity in human serum. • The proposed nanoswitch could be used for inorganic pyrophosphatase inhibitors screening. -- Abstract: Herein, a zinc ion (Zn²⁺)-triggered aggregation induced emission enhancement (AIEE) fluorescence "on-off-on" nanoswitch was fabricated for inorganic pyrophosphate (PPi) and inorganic pyrophosphatase (PPase) activity detection. Dual ligand functionalized Au NCs were utilized as the substrate of the AIEE nanoswitch. The introduction of Zn²⁺ can cause Au NCs aggregated along with the enhanced fluorescence. After the addition of PPi, aggregated Au NCs disaggregated along with decreased fluorescence due to the competitive combination between PPi and Zn²⁺ (on-off). When PPase was introduced, PPi was hydrolyzed and release Zn²⁺, resulting in aggregated Au NCs along with enhanced fluorescence again (off-on). On the basis of this, highly selective and sensitive detection PPi (liner range from 0.1 to 300 μM) and PPase activity (liner range from 0.1 to 10 mU) can be achieved. The detection limits are 0.04 μM for PPi and 0.03 mU for PPase, respectively. Furthermore, the as-prepared Zn²⁺-triggered AIEE nanoswitch was successfully used for quantitative analysis of PPase activity in human serum with satisfactory spiked recoveries, and applied for the inhibitors screening.