Shape-dependent enzyme-like activity of Co 3 O 4 nanoparticles and their conjugation with his-tagged EGFR single-domain antibody.

In this study, Co3 O4 nanopolyhedrons, nanocubes, nanoplates and nanorods were synthesized and characterized. Furthermore, the peroxidase- and catalase-like activities of these Co3 O4 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 Co3 O4 nanopolyhedrons synthesized via coprecipitation method (Co3 O4 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 Co3 O4 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 Co3 O4 NHs (Co3 O4 nanoprobes) were successfully applied to the detection of EGFR expression in NSCLC tissues.