Mesoporous carbon-enriched palladium nanostructures with redox activity for enzyme-free electrochemical immunoassay of brevetoxin B

A new signal amplification strategy based on mesoporous carbon-enriched palladium nanostructure (MSC-PdNS) was designed for enzyme-free electrochemical immunoassay of brevetoxin B (BTB) in marine toxins. The assay was carried out on a BTB-bovine serum albumin-functionalized electrode by using monoclonal mouse anti-BTB-labeling MSC-PdNS as the signal-transduction tag. A competitive-type assay protocol was successfully introduced to develop a high-efficiency enzyme-free immunoassay accompanying the doped palladium nanostructure into MSC-PdNS toward reduction of H₂O₂. Under the optimal conditions, the catalytic current decreased with the increment of BTB concentration in the range from 0.01 to 10 ng mL⁻¹ with a detection limit (LOD) of 5.0 pg mL⁻¹ BTB at the 3s_blank criterion. The selectivity and precision were acceptable. In addition, the methodology was further validated for assaying spiked seafood samples, and consistent results between the electrochemical immunoassay and the referenced enzyme immunoassay were obtained. Importantly, the enzyme-free electrochemical immunoassay provides a promising approach for rapid screening of marine toxin because of its simplicity, low cost, sensitivity, specificity and without the need of sample pretreatment.