Dual-mode colorimetric-electrochemical biosensor for Vibrio parahaemolyticus detection based on CuO2 nanodot-encapsulated metal-organic framework nanozymes

Rapid and accurate detection of Vibrio parahaemolyticus (VP) in a variety of testing environments is critical for preventing the spread of foodborne illnesses. Therefore, a dual-mode colorimetric-electrochemical biosensor was prepared for the rapid and sensitive detection of VP. Phenylboronic acid-decorated CuO2 nanodot-mediated organic metal-organic framework (CP@MOF) nanozymes were constructed to produce colorimetric and electrochemical signals. Furthermore, an electrode surface was fabricated using tetrahedral DNA nanostructure-functionalized poly(amidoamine) dendrimer-Au nanoparticles to specifically bind VP. Under acidic environments, the CP@MOF nanozymes disintegrated, enabling the simultaneous release of Cu2+ and H2O2. This in turn causes a Fenton-type reaction, generating a hydroxyl radical, which then oxidizes 3,3′,5,5′-tetramethylbenzidine, thereby enabling visual detection of VP. Moreover, the produced copper ions can be used for the electrochemical detection of VP. This dual-mode biosensor achieved an accuracy of 88.7 %, which was higher than that of single-mode assays (81.1 %). Hence, this dual-mode assay may facilitate the effective on-site detection of pathogens in shrimp samples.