Facile Synthesis of MnO2 Nanoflowers/N-Doped Reduced Graphene Oxide Composite and Its Application for Simultaneous Determination of Dopamine and Uric Acid.

Xuan Wan,Guangli Li,Quanguo He,Jun Liu,Yonghui Xia,Shihui Yang,Zhaotian Cai,Yabing Ye

doi:10.3390/nano9060847

Abstract

This study reports facile synthesis of MnO2 nanoflowers/N-doped reduced graphene oxide (MnO2NFs/NrGO) composite and its application on the simultaneous determination of dopamine (DA) and uric acid (UA). The microstructures, morphologies, and electrochemical performances of MnO2NFs/NrGO were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), respectively. The electrochemical experiments showed that the MnO2NFs/NrGO composites have the largest effective electroactive area and lowest charge transfer resistance. MnO2NFs/NrGO nanocomposites displayed superior catalytic capacity toward the electro-oxidation of DA and UA due to the synergistic effect from MnO2NFs and NrGO. The anodic peak currents of DA and UA increase linearly with their concentrations varying from 0.2 μM to 6.0 μM. However, the anodic peak currents of DA and UA are highly correlated to the Napierian logarithm of their concentrations ranging from 6.0 μM to 100 μM. The detection limits are 0.036 μM and 0.029 μM for DA and UA, respectively. Furthermore, the DA and UA levels of human serum samples were accurately detected by the proposed sensor. Combining with prominent advantages such as facile preparation, good sensitivity, and high selectivity, the proposed MnO2NFs/NrGO nanocomposites have become the most promising candidates for the simultaneous determination of DA and UA from various actual samples.

Highlights

Dopamine (DA) and uric acid (UA) often coexist in the biological fluids, such as blood serum, urine, and extracellular fluids, which play a vitally significant role on the regulation of human physiological functions and metabolic activities [1]
PThhyesiccarlyCsthaalrlainraezasttirouncture of MnO2 nanoflowers was characterized by X-ray diffraction (XRD)
All of the results indicate that the proposed MnO2 nanoflowers (MnO2NFs)/N-doped reduced graphene oxide (NrGO)/glassy carbon electrodes (GCEs) featured wider linear detection ranges and a lower LOD for the electrochemical oxidation of DA and UA

Summary

Introduction

Dopamine (DA) and uric acid (UA) often coexist in the biological fluids, such as blood serum, urine, and extracellular fluids, which play a vitally significant role on the regulation of human physiological functions and metabolic activities [1]. The DA levels in biological matrixes generally vary from 0.01 μM to 1 μM. The response signals of DA are often susceptible to interferences from endogenous biomolecules i.e., ascorbic acid (AA) and UA. It remains a great challenge for the fast and precise detection of DA. The abnormal concentration of UA in physiological fluids likely leads to several disorders including pneumonia, hyperuricemia, and gout [8].

Methods

Results

Conclusion