Surface Modification of CoO Nanoplates as Efficient Peroxidase Nanozymes for Biosensing Application.

Nanomaterial-based mimetic enzymes, called nanozymes, received more and more attention in recent decades; however, their lack of biocompatibility limited the biomedical applications, which could be solved by surface modification. In this work, the CoO nanoplates were modified by different functional groups, including the amino group, carboxyl group, hydroxyl group, and sulfhydryl group (NH-CoO, COOH-CoO, OH-CoO, and SH-CoO). And the modified CoO nanoplates were characterized by XRD, SEM, TEM, XPS, FTIR, TG, and the Zeta potential, verifying the successful modification of different functional groups. Their mimetic peroxidase properties and kinetics process were further studied and showed that the order of their catalytic activities was as follows: NH-CoO > SH-CoO > COOH-CoO > pure CoO > OH-CoO, and the catalysis of modified CoO nanozymes all followed Michaelis-Menten kinetics. The results indicated that the different functional groups changed their electron transfer ability, and further affected their catalytic activity. HO detection was selected as an application model system to evaluate the modified CoO nanozymes. Compared with other CoO nanozymes, a wider linear range from 0.01 to 40 mmol L and a lower detection limit of 1.5 μmol L was constructed with NH-CoO nanozymes. The results suggested that surface modification by functional groups was a robust strategy to improve the application of CoO nanozymes. The enhanced catalytic activity and good biocompatibility of modified CoO nanozymes provided valuable materials for the relative application, such as medical detection and antioxidation.