A smartphone-integrated NiO/C nanozyme colorimetric sensor for ultra-sensitive on-site detection of organophosphorus pesticides in coastal environments

Abstract

Residues of organophosphorus pesticides (OPs) are a growing problem and a threat to marine ecosystems and public health. The need for rapid on-site detection of OPs has become increasingly urgent. In this study, a rapid, portable and visualized colorimetric sensor based on NiO/C nanozymes with open pore channels was developed for the on-site detection of OPs in an offshore environment. Under the optimal experimental conditions, good detection performance was achieved using dichlorvos as a model, with a linear range of 0.1–10 ng mL⁻¹ and a limit of detection (LOD) of 2.87 × 10⁻³ ng mL⁻¹. By combining a portable smartphone platform with a color picking application, the utility of the method was further improved. The colorimetric sensor enables instrument-free detection of OPs, overcomes the problem of uneven color distribution in traditional paper-based chips, and provides a simple and convenient strategy for the on-site detection of seawater OPs. Finally, a colorimetric sensor for the determination of OPs in real seawater samples was constructed. The results show that the colorimetric sensor has good detection performance and can meet the needs of rapid detection of OPs in the field.