A bimetallic CoNi-based metal−organic framework as efficient platform for label-free impedimetric sensing toward hazardous substances

Abstract A novel bimetallic CoNi-based metal−organic framework (CoNi-MOF) has been synthesized using the mixed organic linkers of 4-(1H-tetrazol-5-yl)benzoic acid (H2TZB) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT), which can be employed as a platform for the feasible construction of label-free impedimetric immunosensor to efficiently detect the trace hazardous substances of deoxynivalenol (DON) and salbutamol (SAL). As compared with the individual Co-MOF and Ni-MOF, the bimetallic CoNi-MOF exhibits much smaller particle sizes and superior electrochemical activity. Owing to the carboxyl groups of H2TZB that can generate electrostatic interaction with the amino groups of antibodies to realize the high immobilization amounts of antibodies, as well as the π−π* stacking and multivalent affinity interactions between CoNi-MOF and antibodies, the as-prepared CoNi-MOF shows excellent biosensing ability toward analytes determined by electrochemical techniques. The developed CoNi-MOF-based electrochemical immunosensor demonstrates high sensitivity with low detection limits of 0.05 and 0.30 pg·mL−1 toward DON and SAL, respectively, in the concentration range of 0.001 to 0.5 ng·mL−1, which also shows good selectivity in the presence of other interferences. Therefore, with the advantages of high sensitivity, good selectivity, and simple operation, this new strategy is believed to exhibit great potential for convenient detection of poisonous and harmful residues in foods.