Cerium ion(III)-triggered aggregation-induced emission of copper nanoclusters for trace-level p-nitrophenol detection in water

Herein, we provide the first report on the effects of Ce 3+ addition on the fluorescence of copper nanoclusters (CuNCs), which have excellent optical properties and lower toxicity as compared to AgNCs and AuNCs. We synthesized glutathione-encapsulated copper nanoclusters (GSH-CuNCs) using a simple one-pot chemical reduction approach. The excitation/emission wavelengths of the GSH-CuNCs were 350/650 nm. Introduction of Ce 3+ triggered an aggregation-induced emission of GSH-CuNCs due to formation of GSH-CuNCs-Ce 3+ complexes, resulting in a prominent fluorescence enhancement (~42-fold) of the mixed system. Fluorescent intensities (FIs) for the GSH-CuNCs-Ce 3+ system were significantly quenched by introduction of p -nitrophenol ( p -NP). The aforementioned quenching mechanism resulted from an inner-filter effect producing nearly unchanged fluorescence lifetime and overlap between UV–Vis absorption of Ce 3+ and the excitation wavelength of GSH-CuNCs. Consequently, a GSH-CuNCs-Ce 3+ -based “ON-OFF” platform was constructed for fluorescent detection of p -NP in water matrices. Under optimized conditions (5-min incubation time, pH = 5.6, 20 mM Ce 3+ ), the FIs of the GSH-CuNCs-Ce 3+ system were linear for p -NP concentrations from 0.5 to 500 μM and achieved a low detection limit of 0.17 μM. Moreover, the as-constructed nanofluoroprobe demonstrated high stability and specificity to p -NP, thereby offering a simple, cheap and robust experimental method for conventional monitoring of p -NP at trace levels in real-world water samples.