In Situ Fabrication of Nanoceria with Oxidase-like Activity at Neutral pH: Mechanism and Boosted Bio-Nanozyme Cascades

Abstract

Catalytic cascades have drawn much attention by avoiding the isolation of intermediates and due to high atom economy. Yet, developing an efficient, one-pot biocatalytic cascade remains challenging. Combined with the selectivity of biological enzymes and tunable activity of nanozymes, we herein demonstrate an effective bio-nanozyme cascade formed by glucose oxidase (GOx) and in situ-generated nanoceria. The prepared H₂O₂-nanoceria complex shows strong oxidative activity for common chromogenic substrates under physiological conditions, which are the optimal reaction conditions for most biological enzymes. Interestingly, GOx not only provides H₂O₂ for the second step reaction but also simultaneously leads to 7.4-fold enhancement of activity. We characterized the process of in situ generation of nanoceria at pH 7.0 and how proteins boost the activity by enhancing product desorption. In addition, the proposed one-pot bio-nanozyme cascade shows high stability and analytical performance for serum glucose with a detection limit of 5 μM.