Integrating Ferroelectric Fields with Active Sites for the Construction of Highly Efficient Nanozymes

Enhancing nanozymes' catalytic activity is challenging yet crucial for practical applications. Herein, inspired by the electrostatic preorganization effect in the catalytic process of natural protein enzymes, a nanozyme is constructed by decorating ferroelectric BaTiO3 nanoparticles (BTO) with hemin, which is often regarded as the active site of natural horseradish peroxidase (HRP). The Hemin-BTO nanozyme demonstrates excellent peroxidase-like (POD-like) activity with the catalytic constant (Kcat) up to 9.71 × 105 s-1 and 1.41 × 106 s-1 for TMB and H2O2 substrates, which is ca. 240-fold and 400-fold greater than that of HRP. Theoretical studies utilizing Density Functional Theory calculations revealed the underlying mechanism. The spontaneous polarization electric field of BTO adjusts the internal electrostatic field of the active site hemin, thereby enhancing the affinity between the Hemin-BTO nanozyme and the substrate. Simultaneously, the existence of hemin reduced the recombination of BTO charge carriers, accelerated electron transfer, and thus promoted the generation of reactive oxygen species, effectively enhancing its POD-like activity. In addition, Hemin-BTO has been successfully used to establish an immunoassay of human brain natriuretic peptide. This work presented a feasible strategy to construct nanozymes with highly catalytic activity by integrating the ferroelectric fields with the active site of natural enzymes.