Redox-active thionine–graphene oxide hybrid nanosheet: One-pot, rapid synthesis, and application as a sensing platform for uric acid Original Research Article

In this paper, we fabricate a sensitive and stable amperometric UA amperometric biosensor using nanobiocomposite derived from thionine modified graphene oxide in this study. A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs) through π–π stacking has been demonstrated. Various techniques, such as UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemistry have been utilized to characterize the formation of the T–GOs. Due to the synergistic effect between thionine and graphene oxide, the nanosheets exhibited excellent performance toward H2O2 reduction. The incorporation of thionine onto graphene oxide surface resulted in more than a twice increase in the amperometric response to H2O2 of the thionine modified electrode. The as-formed T–GOs also served as a biocompatible matrix for enzyme assembly and a mediator to facilitate the electron transfer between the enzyme and the electrode. Using UOx as a model system, we have developed a simple and effective sensing platform for assay of uric acid at physiological levels. UA has been successfully detected at −0.1 V without any interference due to other electroactive compounds at physiological levels of glucose (5 mM), ascorbic acid (0.1 mM), noradrenalin (0.1 mM), and dopamine (0.1 mM). The response displays a good linear range from 0.02 to 4.5 mM with detection limit 7 μM. The application of this modified electrode in blood and urine UA exhibited a good performance. The robust and advanced hybrid materials might hold great promise in biosensing, energy conversion, and biomedical and electronic systems.