Shape-dependent enzyme-like activity of Co3O4 nanoparticles and their conjugation with his-tagged EGFR single-domain antibody

In this study, Co 3 O 4 nanopolyhedrons, nanocubes, nanoplates and nanorods were synthesized and characterized. Furthermore, the peroxidase- and catalase-like activities of these Co 3 O 4 nanoparticles (NPs) were studied and influence of the exposed crystal planes was explored. According to their morphology and peroxidase-like activity, dimercaptosuccinic acid (DMSA) modified Co 3 O 4 nanopolyhedrons synthesized via coprecipitation method (Co 3 O 4 NHs) were selected as a proper candidate for the immunohistochemical (IHC) detection of epidermal growth factor receptor (EGFR) expression in non-small cell lung cancer (NSCLC) tissues. Bivalent cobalt ions were coupled to the carboxyls on the surface of the obtained Co 3 O 4 NHs so as to chelate the hexahistidine residues (His-Tags) at the C-terminal of EGFR single-domain antibodies (EGFR sdAbs). Finally, the as-obtained EGFR sdAbs-binding Co 3 O 4 NHs (Co 3 O 4 nanoprobes) were successfully applied to the detection of EGFR expression in NSCLC tissues.