NiS/Ni₃S₄ Nanoparticles in a N, S Co-Doped Carbon Matrix for Electrochemical Analysis of Mesalazine in Drug and Biological Samples

Herein, a metal–organic framework-derived NiS/Ni 3 S 4 heterostructure embedded in N, S co-doped carbon (NiS/Ni 3 S 4 /NSC) was successfully prepared and applied in electrochemical detection of anti-inflammatory drug mesalazine (MSZ). The exposed sulfur atoms of the NiS/Ni 3 S 4 /NSC composite could efficiently recognize and trap MSZ targets through the S–π interaction. Meanwhile, the active metal centers of NiS/Ni 3 S 4 /NSC revealed a high-performance catalytic property for the oxidation of MSZ on the working electrode surface. The highly efficient adsorption and electrocatalytic abilities of the NiS/Ni 3 S 4 /NSC composite enhanced the electrochemical signals for MSZ detection. Markedly, the glassy carbon electrode modified by NiS/Ni 3 S 4 /NSC (NiS/Ni 3 S 4 /NSC/GCE) featured a low limit of detection (LOD, 4.4 nM) for the electrochemical analysis of MSZ in the 0.05–100 μM concentration range. Moreover, the sensor could avoid the interference of the coexisting species during detection of MSZ and also revealed satisfactory reproducibility, repeatability, and stability. Particularly, the NiS/Ni 3 S 4 /NSC/GCE sensor was used to monitor the contents of MSZ in practical drug, human serum, and urine samples with satisfactory recoveries. The remarkable performance demonstrated that the NiS/Ni 3 S 4 /NSC/GCE sensor could be a prospective candidate for the accurate detection of MSZ in the biomedical fields.