ZIF-67-derived CoO hollow nanocage with efficient peroxidase mimicking characteristic for sensitive colorimetric biosensing of dopamine.

CoO hollow nanocages (CoO HNCs) were prepared by simple calcination with ZIF-67 as the precursor. Compared with ordinary nano-sized CoO, skeletal CoO HNCs have a larger specific surface area and porosity, lead to better dispersion, which can expose more catalytic active sites, and obtain higher catalytic activity. Experiments indicate that CoO HNCs are used as a catalyst to make HO generate O. At the same time, CoO HNCs act as bridge to accelerate the electrons transfer from the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) to the dissolved oxygen and efficiently obtain blue oxidized TMB (oxTMB) at low concentration of HO. Steady-state kinetic analysis shows a lower K and a higher V value than other materials, indicating its excellent affinity and high catalytic efficiency. Based on the inhibitory effect of dopamine (DA) on TMB oxidation in the system, a sensitive, visual colorimetric biosensing method is developed. The calibration curve of DA has a good linear response at both high and low concentrations. Compared with other system, it has the unique advantage of very low detection limit, while retaining a wide detection range, and realizes the accurate detection of actual samples with different concentrations.