Xueliang Niu

Investigation on direct electrochemical and electrocatalytic behavior of hemoglobin on palladium-graphene modified electrode

Palladium-graphene (Pd-GR) nanocomposite was acted as modifier for construction of the modified electrode with direct electrochemistry of hemoglobin (Hb) realized. By using Nafion as the immobilization film, Hb was fixed tightly on Pd-GR nanocomposite modified carbon ionic liquid electrode. Electrochemical behaviors of Hb modified electrode were checked by cyclic voltammetry and a pair of redox peaks originated from direct electron transfer of Hb was appeared. The Hb modified electrode had excellent electrocatalytic activity to the reduction of trichloroacetic acid and sodium nitrite in the concentration range from 0.6 to 13.0mmol·L-1 and from 0.04 to 0.5 mmol·L-1. Therefore Pd-GR nanocomposite was proven to be a good candidate for the fabrication of third-generation electrochemical biosensor.

Three-dimensional reduced graphene oxide aerogel modified electrode for the sensitive quercetin sensing and its application

Quercetin belongs to flavonoid drug that has favorable properties such as antiviral, anticancer, anti-allergic and anti-tumor. Therefore a sensitive method is highly required for quercetin determination. In this paper, a three-dimensional reduced graphene oxide aerogel (3D-rGA) with excellent porous framework was synthesized via one-step hydrothermal technique. The characteristics and performances of 3D-rGA were checked by SEM, TEM, BET, XRD, Raman, FT-IR, XPS and electrochemical methods, which exhibited good properties including unique porous structure, large surface area and excellent conductivity. 3D-rGA was further used as the modifier on carbon ionic liquid electrode (CILE) to construct a modified electrode, which was applied to sensitive and selective determination of quercetin. Electrochemical responses of quercetin were accelerated with a pair of symmetrical cyclic voltammetric peaks in good shape appeared and the electrochemical parameters were calculated. The sensitive oxidation response of quercetin from differential pulse voltammetry was verified. Under the selected conditions, electroanalysis of quercetin was established by plotting the oxidation peak currents against quercetin concentrations with linear regression analysis. A wider linear range from 0.1 μmol/L to 100.0 μmol/L was obtained with a detection limit of 0.065 μmol/L (3S0/S). This as-explored approach could be successfully utilized for quercetin detection in Ginkgo tablets.