Nanopaper Integrated\nSmart Device: An Opto-Electrochemical\nBiosensor for Real-Time Dual On-Field Detection of Organophosphorus\nPesticides

The frequent and excessive use of organophosphorus pesticides\nin\nthe agriculture industry raises persistent concerns regarding their\nenvironmental protection and public health implications. Addressing\nthese issues requires the development of affordable and reliable sensing\nplatforms for on-field monitoring to mitigate their adverse impacts\npromptly. This study utilizes nanocellulose papers (bacterial and\nTEMPO-oxidized) combined with butyrylcholinesterase to create a novel\nreagent-free and orthogonal nanobioplatform featuring smart opto-electrochemical\ndual outputs. An integrated nano-PAD, preloaded with enzymes and enzymatic\nsubstrates, is fabricated using wax-printing and screen-printing technologies.\nThe nano-PAD measures opto-electroactive products, specifically indoxyl\nand thiocholine, whose concentrations correlate directly with the\nenzymatic inhibition caused by paraoxon, used as the organophosphate\nmodel. To enhance user convenience and meet the requirements for smart\nreal-time point-of-need detection, integration of the nano-PAD with\na smartphone-operated miniaturized potentiostat and a self-developed\nportable smart optical reader is achieved. The developed bioanalytical\nplatform, further supported by a self-developed Android application,\nenables accurate and efficient quantification of dual signals in real\ntime. The system covers a wide detection range of paraoxon (20–100\nppb) and demonstrates reliable recovery levels (ranging from 98 to\n107%) in a real matrix, specifically wastewater. Given these demonstrated\ncapabilities, this innovative biosensing strategy holds substantial\npotential for practical application in environmental surveillance,\nfacilitating timely and informed environmental management decisions,\nparticularly in resource-limited settings where traditional analytical\ntools are inaccessible.