Nano-ferroelectric oxidase mimics for colorimetric detection of glutathione

The oxidase-mimicking activity of ferroelectric BaTiO3 nanoparticles (BTO NPs) is reported. In the absence of hydrogen peroxide or oxygen, BTO NPs catalyzed the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and other chromogenic substrates. The catalytic constant (Kcat) was eight times that of fluorescein and 104 times that of bovine serum albumin-protected Se nanozymes. In the mechanism of the chromogenic reaction catalyzed by BTO NPs, the intrinsic electric field of the ferroelectric BTO drove the separation of holes and electrons, and the separated carriers reacted with water to produce reactive oxygen species that oxidized the chromogenic substrates. The BTO NPs-TMB chromogenic system was used to detect glutathione, which restored the blue-colored oxidized TMB to its colorless initial state. There was a good linear relationship between the absorbance change and the GSH concentration over the range 0.50–20 μM, with a 0.2-μM limit of detection. This work not only proposed a new idea of screening and designing nanozymes from ferroelectric materials but also expand the application of ferroelectric nanomaterials to bio-detection.