Defect-engineered BiVO₄ nanozyme sensor array for discriminative detection of anthrax biomarker and its analogues

Detecting dipicolinic acid (DPA), a critical anthrax biomarker, is essential for biosecurity, but faces interference from structurally similar pyridinecarboxylic acids (PAs) using simple techniques. To address this, a colorimetric sensor array based on cation vacancy-engineered bismuth vanadate (BiVO₄) nanozymes was developed. Three types of BiVO₄ nanozymes (r-, m-, and p-BiVO₄) with tunable peroxidase-like activity were synthesized via a facile hydrothermal method. These nanozymes exhibited differential inhibitory responses toward various PAs, attributed to specific metal-coordination interactions. Leveraging this cross-reactivity, the 3-channel sensor array achieved 100% accurate discrimination of seven PAs and their mixtures at concentrations of 10-100 μM using linear discriminant analysis (LDA). The array demonstrated excellent anti-interference capability and was successfully applied to identify PAs in real samples, including tap water, milk, and mango juice. This work provides a novel, efficient, and low-cost strategy for on-site monitoring of anthrax biomarkers, showing great promise for applications in biosecurity and environmental monitoring.