Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12951-022-01536-0/MediaObjects/12951_2022_1536_Fig1_HTML.png)
Characterizations of modified ZnO2 NPs. a Schematic illustration of modified ZnO2 NPs synthesis. b TEM images of ZnO2, ZnC and ZnCM NPs. c Zeta potentials of different NPs. d SDS-PAGE gel analysis of Cat (lane 1: positive control, PC, of free Cat; lane 2: ZnCM NPs). e Concentration changes of dissolved O2 from ZnC and ZnCM NPs under different pH values. f Percentage changes of released Zn2+ ion from ZnC and ZnCM NPs under different pH values