Herein, Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 MNPs) were synthesized via a one‐step counter‐coprecipitation method, and Prussian blue (PB) nanoparticles were subsequently modified in situ on the surface of Fe 3 O 4 MNPs. The obtained PB/Fe 3 O 4 composite magnetic nanoparticles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. The results demonstrated that PB/Fe 3 O 4 exhibited excellent peroxidase‐like catalytic activity and followed Michaelis–Menten kinetics in the presence of H 2 O 2 and 3,3′,5,5′‐tetramethylbenzidine. Taking advantage of the intrinsic peroxidase‐like activity of PB, Fe 3 O 4 MNPs, and their synergistic effects, a novel nitrite (NO 2 − ) signal‐enhanced electrochemical sensing platform was developed by first modifying a magnetic glassy carbon electrode (MGCE) with PB and then drop‐casting the PB/ Fe 3 O 4 composite nanoparticles. The resulting PB/ Fe 3 O 4 /PB/MGCE sensor exhibited high sensitivity and selectivity toward NO 2 − detection. Under optimized conditions, the sensor achieved a detection limit of 0.03588 μM (S/N = 3). Furthermore, the proposed peroxidase‐like signal‐enhanced electrochemical sensor was successfully applied to detect NO 2 − in sausage, bacon, and pickled mustard tuber samples. Overall, this novel signal‐enhanced electrochemical sensing strategy offers great potential for applications in food quality control and safety monitoring.
Chen et al. (2026) studied this question.