Hong Yan Yue

ZnO nanowire arrays on 3D hierachical graphene foam: biomarker detection of Parkinson's disease.

We report that vertically aligned ZnO nanowire arrays (ZnO NWAs) were fabricated on 3D graphene foam (GF) and used to selectively detect uric acid (UA), dopamine (DA), and ascorbic acid (AA) by a differential pulse voltammetry method. The optimized ZnO NWA/GF electrode provided a high surface area and high selectivity with a detection limit of 1 nM for UA and DA. The high selectivity in the oxidation potential was explained by the gap difference between the lowest unoccupied and highest occupied molecular orbitals of a biomolecule for a set of given electrodes. This method was further used to detect UA levels in the serum of patients with Parkinsons disease (PD). The UA level was 25% lower in PD patients than in healthy individuals. This finding strongly implies that UA can be used as a biomarker for PD.

Synthesis of ZnO nanowire arrays/3D graphene foam and application for determination of levodopa in the presence of uric acid

Three-dimensional (3D) graphene foam (GF) was prepared by chemical vapor deposition (CVD) using nickel foam as the template. ZnO nanowire arrays (ZnO NWAs) were vertically grown on the 3D GF by hydrothermal synthesis to prepare ZnO NWAs/GF. This hybrid combines the properties of ZnO NWAs and 3D GF, which has favorable electrocatalysis and outstanding electrical conductivity. The vertically aligned ZnO NWAs grown on the GF enlarged the electroactive surface area, which was investigated from the Fe(CN)63-4+ redox kinetic study. The ZnO NWAs/GF was used as an electrochemical electrode for the determination of Levodopa (LD) in the presence of uric acid (UA). The electrochemical responses of the ZnO NWAs/GF electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results show that the sensitivity of the electrode for LD is 3.15μAμM-1 in the concentration range of 0.05-20μM and the measured detection limit of the electrode for LD is 50nM. The electrode also shows good selectivity, reproducibility and stability. The proposed electrode is succsefully used to determine LD in human plasma samples and it is potential for use in clinical research.

Effect of Hydrothermal Reaction Conditions on the Sizes and Morphologies of ZnO Nanorods

The influence factors of hydrothermal treatment on the formation process of ZnO nanorods are investigated involving with hydrothermal temperature, time and precursor concentration. The as-obtained products were characterized by Scanning Electron microscope (SEM) and X-ray diffraction (XRD), respectively. XRD result indicates that the obtained ZnO nanorods are high-quality single crystals. SEM results indicate that both the diameter and the length of ZnO nanorods increase with increasing the hydrothermal time and temperature. The precursor concentration prominently determines the morphologies of ZnO nanostructure from initial particle morphology to rod-like, and to final slice-like morphology.