Bioinspired 3D hierarchical BSA-NiCo2O4@MnO2/C multifunctional micromotors for simultaneous spectrophotometric determination of enzyme activity and pollutant removal

Abstract

Artificial self-propelled micro/nano-motors have emerged as a promising hot spot in the fields of water-body remediation and environmental protection. Herein, we report a novel multifunctional micromotors with dual enzyme-like activities for simultaneous colorimetric determination and removal of environmental contaminants. Thanks to the tubular morphology inherited from kapok fibers, these bovine serum albumin-functionalized NiCo2O4@MnO2/C (BSA-NiCo2O4@MnO2/C) micromotors with dual oxidase/peroxidase-like activity can move forward quickly in aqueous solutions via a bubble recoil mechanism, which can not only enhance the colorimetric sensing performance, but also improve the removal efficiency toward Cu2+ ion by enhancing the mass transfer both in the detection and catalytic degradation systems. Moreover, the unique 3D hierarchical architecture assembled by core-shell NiCo2O4 @MnO2 nanosheets and C microtubes can provide more accessible reactive sites and thus dramatically facilitate such detection process. In combination with the autonomous motility, intrinsic oxidase/peroxidase-like activities and precisely tuned hierarchical architecture, these automatic micromachines not only are able to detect Cu2+ selectively and sensitively with the limit of detection of 2.0 nM, but also quickly remove Cu2+ from wastewater with maximal adsorption capacity of 161.8 mg g−1. Furthermore, these micromotors exhibit excellent catalytic activity for the degradation of tetracycline hydrochloride. This multifunctional mobile platform will provide a new and promising strategy for the simultaneous detection and decontamination of poisonous metal ions and other pollutants in aqueous samples.