5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized urchin-like CuCoO as an excellent artificial nanozyme for determination of dopamine.

Urchin-like peroxidase mimics 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized CuCoO nanospheres (Por-CuCoO) has been fabricated as an excellent visual biosensor. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) have been employed to characterize the composition, morphologies, and elemental analysis of the as-synthesized Por-CuCoO. The catalytic activity of Por-CuCoO was evaluated by the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) with the aid of HO, which exhibited a visual blue change with an absorption maximum at 652 nm for only 10 s. The peroxidase-like behaviors of Por-CuCoO conformed to the Michaelis-Menten equation. Electrochemistry, radical scavenger, and fluorescence probe experiments verified that electron transfer, •O radicals, and holes (h) are the important factors during the catalytic oxidation of TMB. Based on the inhibition of dopamine (DA) on TMB oxidation, the Por-CuCoO-based colorimetric biosensor has been successfully constructed for sensitive determination of DA witha detection limit (LOD) of 0.94 μΜ. In addition, colorimetry was validated to detect DA in serum samples with high sensitivity and good selectivity. 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized urchin-like CuCoO (Por-CuCoO) with excellent peroxidase activity, ascribed to the synergistic effect between •O radicals and holes (h). A fast colorimetric sensor on the basis of Por-CuCoO has been constructed to quantitatively determine dopamine concentration in human serums.