Laser-generated defect-rich MnOx nanobelts with high oxidase mimic activity for glutathione detection

Nanozymes with oxidase (OXD) mimic activity have shown great prospects for biomarker sensing, but their lower activity compared to natural enzymes has limited their further application. The catalytic activity of OXD mimics can be remarkably improved by material morphology design and defect engineering. In this work, we developed MnOx nanobelts (NBs) using a laser irradiation in liquid (LIL) technique. Among the MnOx NB structure, the ultrathin layered structure was conducive to exposing the catalytic active sites of the MnOx NBs, and the negative charge layer of the birnessite-type MnOx NBs helped to improve the affinity for positive substrate 3,3’,5,5’-tetramethylbenzidine (TMB). Importantly, laser-irradiation-generated oxygen vacancies significantly reduced the adsorption energy of the MnOx NBs for oxygen. As expected, the excellent substrate affinity (Km = 0.0087 mM) and high catalytic rate (Vmax = 6.04 × 10−7 M/s) of the MnOx NBs as OXD mimics were verified. Meanwhile, based on the inhibition of glutathione (GSH) on the OXD mimics, we established a fast and highly sensitive method for GSH determination. These new findings may provide a new strategy for synthesizing highly active nanozymes for biomarker applications.