ssDNA-tailorable oxidase-mimicking activity of spinel MnCo2O4 for sensitive biomolecular detection in food sample

Nanozyme technique with efficient modulating strategies is a promising tool for biocatalytic and biosensing applications, yet insights into target-responsive controllability of oxidase nanozymes remain largely unknown. In this contribution, we report a state-of-art oxidase-like and ssDNA-tunable nanozyme for biomolecular recognition. In detail, the spinel-type manganese cation substituted cobalt oxide (MnCo2O4) submicrospheres can imitate oxidase for efficiently catalytic oxidation of colorimetric substrate, superior to current metal oxide-based oxidase nanozymes. More importantly, the nanozyme activity of spinel MnCo2O4 can be reversibly inhibited by the attachment/detachment of aptamer strands on MnCo2O4 surface via the aptamer-target binding event, enabling a new colorimetric access for detecting biomolecules. Taking highly toxic ochratoxin A (OTA) as model molecule, we can selectively determine OTA in maize samples with a limit of detection (3 delta/S) of 0.08 ng/mL. The unique nanozyme property of spinel MnCo2O4, together with the principle of our approach, reveals the potential of ssDNA-tailorable oxidase nanozymes in biocatalytic and biosensing fields. (C) 2018 Elsevier B.V. All rights reserved.