Portable Electroanalytical Platform Based on Eco-Friendly Biomass-Based Hydrogels with Bimetallic MOF Composites for Trace Acetaminophen Determination

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