Unlocking potent oxidase-like activity in bimetallic MnCo-MOFs: A nanozyme-based immunoassay for rapid detection of a Lumpy skin disease virus protein

Abstract

Background: The escalating economic threat of Lumpy skin disease (LSD) demands rapid, point-of-care diagnostic tools that overcome the limitations of conventional methods. Current nanozyme-based assays are often limited by their reliance on unstable hydrogen peroxide (H₂O₂). Our goal was to engineer a potent, H₂O₂-free oxidase-like (OXD-like) nanozyme to enable a simpler and more robust point-of-care immunoassay for the LSD virus (LSDV).

Results: A bimetallic manganese-cobalt metal-organic framework (MnCo-MOF) was synthesized, where strategic cobalt doping unlocked potent intrinsic OXD-like activity for direct colorimetric reactions. An immunoassay was developed by conjugating specific antibodies to the MnCo-MOF surface. The target LSDV ORF-122 protein obstructed the nanozyme's active sites and triggered particle aggregation, inhibiting the catalytic signal. This method detected the ORF-122 protein with a limit of detection (LOD) of 0.0355 μg/mL in just 10 min and demonstrated excellent specificity.

Significance: This study presents the first H₂O₂-free nanozyme immunoassay for a key LSDV protein, providing a practical tool for on-site disease surveillance. It establishes a powerful design strategy-unlocking potent OXD-like activity in bimetallic MOFs-that offers a robust blueprint for a new generation of field-deployable diagnostics for diverse biomedical and environmental targets.

Keywords: Bimetallic MOF; Colorimetric immunoassay; Lumpy skin disease; Oxidase-like.