Enhanced oxidase-like activity of Mo-MnO2 nanozymes for colorimetric sensing of isoniazid and ascorbic acid

A novel Mo-MnO 2 nanoflowers (NFs) with oxidase-like (OXD-like) activity was performed by microwave-assisted hydrothermal synthesis, and the doping of Mo resulted in enhanced enzyme-like activity and stronger affinity for the chromogenic substrate 3,3′,5,5′-Tetramethylbenzidine (TMB) than single MnO 2 by the same synthesis method. In the presence of oxygen, Mo-MnO 2 NFs oxidized the colorless TMB to blue oxTMB, and the addition of isoniazid and ascorbic acid inhibited the color development reaction. Besides, it was further investigated that the inhibitory mechanism of INH and AA on the color development reaction of Mo-MnO 2 -TMB system, mainly due to the electrostatic interaction. The absorbance change of oxTMB at 652 nm could be used to quantitative detect isoniazid (INH) and ascorbic acid (AA). The linear ranges of colorimetric detection were 1–40 μM for INH and 1–30 μM for AA, and the limits of detection (LOD) were 0.436 μM for INH and 0.579 μM for AA, respectively. The successful application of this sensing platform in real samples further validated its practicality, demonstrating the broad potential in the field of colorimetric sensing.