CeO2@NC nanozyme with robust dephosphorylation ability of phosphotriester: A simple colorimetric assay for rapid and selective detection of paraoxon

Enzyme-mediated dephosphorylation reaction is the important approach to realize the inactivation and detection of hazardous phosphate chemicals. To date, many phosphatases-like nanozymes (e.g., CeO2) have demonstrated the catalytic hydrolysis ability of the phosphomonoesters, rather than phosphotriester, and the CeO2 nanozyme only work under relatively harsh conditions of high temperature, and large dosage. Thus, exploration of efficient nanozymes for the rapid dephosphorylation of phosphotriester under mild conditions remains a challenge. Here, a novel CeO2@NC nanozyme is developed with excellent phosphatases-like activity based on substrate syner-gistic effect, in which, CeO2 nanoparticles embedded in N-doped carbon (NC) material. Taking paraoxon as the model substrate, such CeO2@NC nanozyme can drive rapid dephosphorylation of phosphotriester over a broad temperature range, which not only significantly outperforms natural phosphatases and neat CeO2, but also can preserve >80% of the optimal activity after exposure of harsh conditions, such as strong acidic/basic medium, high temperature of up to 80 degrees C. The excellent catalytic performance could be due to that Ce(IV)/Ce(III) species act as the active sites to realize the polarization and hydrolysis of P-O bond while NC template works as the synergistic group to adsorb the substrate. Furthermore, a simple colorimetric assay is developed for the rapid and selective detection of paraoxon. Overall, this work not only develops a highly efficient phosphatases-like nanozyme via substrate synergetic strategy, but also opens an interesting avenue for the rapid detection of organophosphorus pesticides.

Automated summary

Enzyme-mediated dephosphorylation is a crucial method for inactivating and detecting hazardous phosphate chemicals. In this study, a novel CeO2@NC nanozyme with excellent phosphatase-like activity was developed based on substrate synergistic effect. This nanozyme can rapidly dephosphorylate phosphotriester under mild conditions and maintain over 80% optimal activity even in harsh conditions. Additionally, a simple colorimetric assay for the rapid and selective detection of paraoxon was also developed. Overall, this work not only provides a highly efficient nanozyme for enzyme-mediated dephosphorylation, but also offers a new avenue for rapid detection of organophosphorus pesticides.