Bioinspired Surface Modification of Graphene-Based Hybrids as Nanozyme Sensors for Simultaneous Detection of Dopamine and Uric Acid

Development of hybrid nanozymes with high catalytic efficiency is of critical importance for enzyme mimics in biological catalytic fields. Herein, we reported a polydopamine (PDA) surface modification-assisted pyrolysis strategy for preparing CoO nanoparticles/N-doped carbon sheets/reduced graphene oxide composites (CoO/N-CS-rGO). In this strategy, PDA with abundant amines and imines could serve as an eco-friendly N-contained precursor and a connecting agent between GO matrix and CoO. Due to the superior conductivity of N-CS-rGO, synergistic catalysis between CoO nanoparticles (NPs) and N-CS-rGO, and intrinsic oxidase-like characteristic, the CoO/N-CS-rGO was used as an ultrasensitive signal amplification platform for simultaneously analyzing dopamine (DA) and uric acid (UA) in a neutral solution. Significantly, the fabricated electrochemical sensor showed ultrahigh sensitivities of 1378 μA mM–1 for DA and 1393 μA mM–1 for UA. The linear range of 0.5–110 μM for DA and 1–125 μM for UA could be obtained by this sensor. Furthermore, the stability and selectivity of the CoO/N-CS-rGO-based hybrid biosensor were evaluated. The results showed that the biosensor performed good stability and brilliant selectivity against interfering analytes. Also, the CoO/N-CS-rGO/GCE was adopted to monitor two analytes in human serum samples with high accuracy. This work provides an efficient PDA-assisted synthetic strategy to prepare hybrid nanomaterials and shows broad prospects for biosensing, biotechnology, and clinical diagnosis.