Programming of a Portable Digital Monitoring System-Integrated DNA Aptamer Reversely Regulated Oxidase-Like Nanozyme for Real-Time Dynamic Analysis of Atmospheric Perfluorooctanoic Acid

Timely and efficient analysis of the fluorinated per- and polyfluoroalkyl substances (PFAS) in an atmospheric environment is critical to environmental pollution traceability, early warnings, and governance. Here, a portable, reliable, and intelligent digital monitoring device for onsite real-time dynamic analysis of atmospheric perfluorooctanoic acid (PFOA) is proposed. The sensing mechanism is attributed to the oxidase-like activity of PtCoNPs@g-C₃N₄ that is reversely regulated by the surface modification of a PFOA-recognizable DNA aptamer, engineering a PFOA-activated oxidase-like activity of nanozyme (Apt-PtCoNPs@g-C₃N₄) to combine the nonfluorescence o-phenylenediamine (OPD) as the dual-modality response system. The present PFOA interacts with its DNA aptamer and dissociates from the surface of Apt-PtCoNPs@g-C₃N₄, restoring the oxidase-like activity of PtCoNPs@g-C₃N₄ to oxidize OPD into yellow fluorescence 2,3-diphenylaniline (DAP), thereby observing a PFOA-triggered colorimetric as well as fluorescence dual-modality change. Then, a hydrogel kit-programmed Apt-PtCoNPs@g-C₃N₄ + OPD system is used as the sensitive element to incorporate into this homemade portable device, automatically gathering and processing the PFOA-triggered hydrogel colorimetric and fluorescence image gray values by our self-weaving software, ultimately realizing the onsite real-time dynamic analysis of atmospheric PFOA surrounding a fluorochemical production plant. This work provides a direction and theoretical foundation for designing portable onsite screening devices that cater to other atmospheric contaminants detection requirements.