AI-Integrated Molecularly Imprinted Gate-Controlled Nanozyme-Based Field-Deployable Multimodal Assay of Per- and Polyfluoroalkyl Substances in Environmental Waters

The significant risks posed by per- and polyfluoroalkyl substances (PFAS) to water quality and public health have attracted increasing attention as a class of emerging contaminants. Efficient onsite assay of PFAS in environmental waters is critical for risk traceability, early warning, and safeguarding water security, yet it is hindered by challenges in accuracy, practicality, and intelligence. Here, we proposed a universal artificial intelligence (AI)-assisted molecularly imprinted polymer (MIP) gate-controlled the enzyme-like activity of nanozyme strategy-driven multimodal onsite assay for PFAS in environmental waters, with perfluorooctanoic acid (PFOA) selected as the model target. Briefly, MIP-encapsulated Fe-doped coordination polymer (MIP@Fe-BDC) nanozyme was prepared, and MIP@Fe-BDC possessed peroxidase-like (POD-like) activity. Owing to the selective binding capability conferred by MIP, only PFOA could inhibit POD-like activity of MIP@Fe-BDC. This inhibition prevented the oxidation of colorless 3,3',5,5'-tetramethyl-benzidine (TMB) to its blue oxidized form (oxTMB), thereby interrupting the colorimetric and photothermal signal enhancement as well as the fluorescence signal quenching triggered by oxTMB, resulting in a linear response between PFOA and colorimetric/fluorescence/photothermal signals. To achieve onsite detection, a low-cost MIP@Fe-BDC-based test paper was developed. Multimode images were collected via a smartphone and a thermal imager, and then analyzed using a residual neural network with 18-layer (ResNet18) model for real-time quantitative feedback, in which the whole detection process was completed in just 8.0 min. Moreover, these results were consistent with those obtained using the liquid chromatography-mass spectrometry (LC-MS) method, implying the superior accuracy. This work provides an innovative and universal solution for the portable, low-cost, rapid, efficient, and intelligent onsite surveillance, traceability, and early warning of PFAS in environmental waters, which is of great significance for preventing and controlling environmental water pollution and protecting public health.