Microfluidic Electrochemical Immunosensor Based on High-Entropy Oxide Nanozymes for On-Site Determination of Meat Authenticity

Meat adulteration poses severe risks to food safety, demanding rapid, portable, and sensitive detection methods for meat authenticity verification. Herein, a microfluidic electrochemical immunosensor was developed for on-site detection of pork adulteration in beef and lamb. Spinel high-entropy oxide (HEO) nanozymes with intrinsic peroxidase-like (POD-like) activity and high conductivity were used as dual-functional signal amplifiers. HEO nanoparticles were first immobilized on in-house-fabricated disposable screen-printed electrodes (SPEs) and then covalently conjugated with anti-porcine IgG capture antibodies to construct the capture electrode (Ab-HEO/SPE). When porcine IgG was captured by immobilized antibodies to form sandwich immunocomplexes on the electrode surface, HEO intrinsic POD-like activity catalyzed TMB-H2O2 oxidation to generate electroactive ox-TMB and accelerated interfacial electron transfer to enhance the redox current, thereby achieving specific porcine IgG detection with a linear range of 0.01−50 ng/mL and a limit of detection (LOD) of 16 pg/mL. The sensing interface was integrated into a closed, vertically stacked microfluidic chip, avoiding tedious electrode pretreatment and minimizing operational errors and contamination. This work provides a portable immunosensing prototype and a universal strategy for on-site detection of food safety hazards.