Zeolitic imidazolate framework-8 capped gold nanoclusters as an “on-off-on” fluorescent nanoprobe for sensitive detection of MnO4− and ascorbic acid

Herein, zeolitic imidazolate framework-8 capped gold nanoclusters (AuNCs@ZIF-8) was fabricated and developed as an “on-off-on” fluorescent nanoprobe for selectively and sensitively detecting KMnO 4 and ascorbic acid (AA). The prepared AuNCs@ZIF-8 initially exhibited strong fluorescence at 595 nm KMnO 4 could quench the fluorescence of AuNCs@ZIF-8, rendering the fluorescence signal of AuNCs@ZIF-8 in the “off” state. The probe allows KMnO 4 to be detected with a 10 nM detection limit and the linear analytical range was 0.05–2 μM. When AA was added into the AuNCs@ZIF-8/KMnO 4 system, the fluorescence of the AuNCs@ZIF-8 recovered due to the redox reaction between KMnO 4 and AA, and the fluorescence signal of the system turned “on”. The detection limit of AA was 37 nM in a good linear concentration range of 0.05–5 μM. Furthermore, this AuNCs@ZIF-8 nanoprobe was successfully used for AA detecting in fresh orange juices with the recoveries ranged from 96.6% to 108.2%, which validates the potential applicability of this strategy.