Dual-readout performance of Eu3+-doped nanoceria as a phosphatase mimic for degradation and detection of organophosphate.

Eu3+-Doped nanoceria (Eu:CeO2) with self-integrated catalytic and luminescence sensing functions was synthesized by a simple and gentle one-pot method to build a dual-readout nanozyme platform for organophosphate compound (OPC) sensing in this work. The catalytic degradation of the model substrate of OPC, p-nitrophenyl phosphate (p-NPP), by as-prepared Eu:CeO2 can be completed in 2 min with little influence of temperature and pH values, highlighting the advantages of Eu:CeO2 as an artificial enzyme for dephosphorylation. Most importantly, the characteristic red emission of Eu3+ (592 nm) from Eu:CeO2 can be quenched by p-NPP, accompanied by a color change from colorless to yellow. Based on this, linear ranges of 4-50 μM with a detection limit of 3.3 μM and 1-20 μM with a detection limit of 0.6 μM for p-NPP were obtained by colorimetric and fluorescence methods, respectively. Furthermore, the fluorescence strategy was effectively applied to the determination of ethyl para-nitrophenyl (EPN), one of the most commonly used pesticides, with a detection limit of 5.86 μM. The proposed strategy was also successfully applied to the assay of p-NPP and EPN in real water samples, showing great application prospects in detecting OPC in the environment.