DFT-Guided Design of a Multi-Enzyme Mimetic High-Entropy Nanozyme for Cascaded Glutathione Detection and...

Despite of the various advantages of Prussian blue analogs (PBA), most of the previous studies rely on conventional empirical and trial-and-error methods for identifying the effective catalytic activity. Theory-guided design using predictive models is leading a new revolution in the field of nanozymes, which has yet to focus on PBA. Herein, a series of PBAs, including binary, ternary, quaternary, quinary, and high-entropy, are first investigated by density functional theory (DFT) calculations. Both DFT and experimental results prove the superior catalytic activity of high-entropy than medium- and low-entropy PBAs, mainly owing to the enhanced d-band centers near the Fermi energy level (E_F). The proposed high-entropy PBA oxide (HEO, MnCoNiCuZnFe) demonstrates multi-enzymatic activities. To achieve the colorimetric detection of glutathione (GSH), a colorimetric system with 3,3',5,5'-tetramethylbenzidine (TMB) and H₂O₂ is employed and exhibits a low detection limit, excellent selectivity, remarkable reusability, and long-term stability. Moreover, DFT calculations elucidate the electronic structure by revealing the Gibbs free energy of H₂O₂ dissociation on individual transition-metal sites. Additionally, a microfluidic paper-based analytical device for the point-of-care testing (POCT) of GSH is successfully developed. This study not only provides a rational design strategy for multi-metallic nanomaterials, but also expands the application of high-entropy PBA nanozymes.