Rational construction of particle-in-tube structured NiO/CoO/polypyrrole as efficient nanozyme for biosensing

Nanozymes are a new type of enzymes with ultrahigh environmental stability while facing the issues of low activity and poor specificity. Fabricating a confined structure has been verified to be an ideal strategy to optimize the catalytic performance of nanozymes. In this study, a particle-in-tube structured NiO/CoO/polypyrrole (PPy) is prepared via an electrospinning, calcination, vapor-phase deposition and thermal reduction route. Due to the novel confined structure and synergistic effect between different components, the boosted peroxidase (POD)-like properties are revealed. Furthermore, the prepared NiO/CoO/PPy nanotubes exhibit excellent long-term stability and multi-batch reproducibility for POD mimicking. In addition, a catalase (CAT)-like property is also achieved. Based on its desirable POD-like performance, a rapid colorimetric sensing platform to detect glutathione (GSH) is established with a low detection limit of 0.02 μM (S/N = 3) and favorable selectivity. We believe that this work presents a new strategy to construct high-efficiency nanozymes and excavates its potential in biosensing application.