Colorimetric sensing array based on Fe single-atom nanozyme for ultrasensitively discriminating organophosphorus...

Pesticide residue monitoring is of vital importance in ensuring food safety and promoting public health. In contrast to traditional approaches, colorimetric sensor arrays enable rapid, intuitive, and cost-effective simultaneous detection of multi-pesticides.

In this study, we constructed a three-channel colorimetric sensor array based on the catalytic oxidation of various substrates mediated by a synthesized Fe-N/C single-atom nanozyme (Fe-N/C SAN). Distinct color responses and fingerprint-like patterns were generated for six organophosphorus pesticides (OPs), as each pesticide differentially modulated the oxidase-like activity of Fe-N/C SAN. The developed sensor array achieved 100% discrimination of six OPs within a concentration range of 1-100 ng/mL through standard statistical analysis to extract pesticide feature values from extensive signal data, and enabled reliable identification of different concentrations and mixtures. Additionally, by integrating smartphone with RGB analysis, a platform for intelligent and on-site detection of the six OPs in fruit samples was developed.

The established classification model was evaluated using leave-one-out cross-validation (LOOCV) and obtained satisfactory accuracy. The robust recognition performance demonstrated the practical effectiveness of the sensor array.