Xiao_2022_J.Colloid.Interface.Sci_635_481

Nanomaterials-based enzyme mimics (nanozymes), by simulating enzyme catalysis, have shown potential in numerous biocatalytic applications, but nanozymes face significant challenges of catalytic activity and reusability that may restrict their practical uses. Herein, we report facile fabrication of surface-clean IrO(2) clusters supported on dendritic mesoporous silica nanospheres (DMSNs), which exhibit superior peroxidase-like activity, high thermal/long-term stability, and good recyclability. The IrO(2) clusters (1.4s+/-s0.2snm in size) are obtained by the laser ablation without any ligands and possess negative surface charge, which are efficiently loaded on the amino-functionalized DMSNs by electrostatic adsorption. Owing to morphological and structural advantages, the resulted DMSN/IrO(2) heterostructure displays outstanding peroxidase-like catalytic performance. Compared with horseradish peroxidase, it shows comparable affinities but higher reaction rate (2.95sxs10(-7)sM.s(-1)) towards H(2)O(2), resulting from rapid electron transfer during the catalysis. This value is also larger than those of mesoporous silicas supported metal or metal oxides nanoparticles/clusters in the previous studies. Benefitting from excellent peroxidase-catalysis of the DMSN/IrO(2), the colorimetric assays are further successfully established for the detection of acetylcholine esterase and its inhibitor, showing high sensitivity and selectivity. The work provides novel design of supported nanozymes for biosensing.