VEGFA and neoplasm: Likewise, Gu’s groups developed avastin antibody-functionalized Co3O4 nanozymes as target-specific peroxidase mimics for immunohistochemical staining of vascular endothelial growth factor (VEGF) in tumor tissues and the concentration of Ab-Co3O4 was 15 μg/ml, 100 μL, and the reactive time was 30 min for DAB staining (Dong et al., 2014).