Interfacial structure-modified nanozyme drives single-receptor-single-reaction-unit multichannel sensor array for pesticide discrimination.

Sensor arrays perform well in distinguishing subtle changes induced by structurally similar multi-target analytes in complex systems. However, the construction of most sensor arrays requires multiple receptors and sensing units, increasing detection complexity. Here, we developed Co3O4@Bi nanozymes with a Co-O-Bi interfacial structure, which is devoted to the construction of a single-receptor-single-reaction-unit multichannel sensor array. The Co-O-Bi interfaces facilitate electron transfer from Co to O and then to Bi and weaken the oxygen adsorption capacity. Compared to the Co3O4 nanozymes with repetitive metal Co-O-Co structural units, the resultant Co3O4@Bi nanozymes show a 3.6-fold enhancement in peroxidase-like activity, of which the oxidase-like performance exhibits a decline. As a result, the catalytic activity and selectivity of the Co3O4@Bi nanozymes were improved by introducing Co-O-Bi interfacial structures. Taking Co3O4@Bi as a single receptor and a typical chromogenic reaction as the single reaction unit, the sensor array was established and displayed three distinct characteristic peaks. Based on the different inhibition effects of various pesticides on the activity of Co3O4@Bi nanozyme, the characteristic peaks act as multiple signal channels, enabling the 100% discrimination of five pesticides during the combined use of multiple pesticides. In addition, the colorimetric sensor array can accurately identify the target pesticides with good selectivity and anti-interference capability. This work not only offers a new feasible strategy for the design of nanozymes with an interfacial structure but also addresses the reliance of traditional sensor arrays on multiple receptors and units.