Portable Electroanalytical Platform Based on Eco-Friendly\nBiomass-Based Hydrogels with Bimetallic MOF Composites for Trace Acetaminophen\nDetermination

Accurate acetaminophen (APAP) determination\nusing smartphone-based\nportable sensing hinges on developing sensing interfaces with effective\ncatalytic performance and high electron transfer efficiency. Herein,\nwe report that various Ni-based bimetallic-organic framework materials\n(MOFs) were synthesized through the hydrothermal method. These MOFs\nwere incorporated with multiwalled carbon nanotubes (MWCNTs) during\nthe synthesis of chitosan-cationic guar gum hydrogels (HG). The resulting\ncomposite conductive hydrogel features a distinctive three-dimensional\nnetwork structure with a large specific surface area, enhancing APAP\nenrichment and electrocatalytic activity. Among them, CuNi-MOF-based\nchitosan-cationic guar gum conductive hydrogel (CHG/CuNi-MOF) has\nthe most desirable capability as a signal amplifier. Under optimal\nconditions, the sensor constructed with the screen-printed electrode\n(SPE) using CHG/CuNi-MOF (CHG/CuNi-MOF/SPE) has a wide detection range\n(0.07–1500 μM), a low detection limit (0.023 μM),\nand a relatively high sensitivity (0.0450 μA·μM<sup>–1</sup>·cm<sup>–2</sup>) for the APAP determination.\nIn addition, CHG/CuNi-MOF/SPE has good stability, repeatability and\nanti-interference properties, which make it possible to achieve selective\ndetermination of targets in complex analysis and ultimately obtain\nsatisfactory recoveries (97.6–104.2%). This work successfully\nproves the feasibility of the application of MOFs-based conductive\nhydrogel in the electrochemical detection of phenolics in actual samples.