Study On Non-enzymatic Electrochemical Sensors For Superoxide Anion And Hydrogen Peroxide

Reactive oxygen species (ROS) mainly refer to the highly reactive molecules of oxygen or oxygen-containing. When the concentration of ROS exceeds the normal physiological level in vivo, it will cause oxidative damage, which induces the cells to lose their normal physiological function, and leads to all kinds of diseases. Superoxide anion (O2-) and hydrogen peroxide (H2O2) are the original sources of ROS. Therefore, it is important to detect O2·- and H2O2 in the diagnosis and treatment of disease.Electrochemical sensors have been widely applied in clinical medicine, biological analysis, environmental protection, food testing and so on, due to its high sensitivity, good stability, excellent selectivity, fast response, simple equipment, easy operation, low cost, and continuous monitoring online. The modified materials on the electrode are closely related to the performance of the electrochemical sensor, thus finding suitable electrode material to improve the performance of electrochemical sensors has been a hot research. Nanomaterials can greatly improve the sensitivity, reproducibility and stability of the electrochemical sensor. A new generation of electrochemical sensor based on nanomaterials or its composite materials has become a hot research topic. Based on the above analysis, we have developed several kinds electrochemical sensors, The main research contents are as follows:(1) A novel hydrogen peroxiden on-enzymatic electrochemical sensor was fabricated by immobilizing platinum nanoparticles (PtNPs) and prussian blue (PB) onto the glassy carbon electrode (GCE) surface which has already modified with multi-walled carbon nanotubes (MWCNTs). The electrocatalytic reduction of H2O2 was studied. The results demonstrated that the synergistic effect of PB, PtNPs and MWCNTs can significantly improve the detection performance of the sensor for H2O2 at applied potential of -0.05 V. The fabricated sensor provides linear amperometric responses for H2O2 in the concentration range of 5?4205 ?M, with a sensitivity of 758 ?A·mM-1·cm2 and a detection limit of 0.30 ?M (S/N= 3).(2) A novel superoxide anion non-enzymatic electrochemical sensor was fabricated by immobilizing PtRuCu ternary alloy nanoparticle and the "ribbon like" of folded structure of graphene onto GCE surface using electrochemical methods. The morphology of the composites was characterized by the scanning electron microscopy(SEM), and the electrocatalytic reduction of O2·- was studied by CV, EIS and i-t. The results showed that the PtRuCu/ERGO/GCE presents satisfactory analytical performance with high sensitivity, wide linear range, excellent selectivity, good reproducibility and stability for detection of O2-, which attributes to the synergistic effect of ERGO and PtRuCu ternary alloy nanoparticles.(3) Directly electropolymerized PEDOT-Fe(CN)64- on the GCE modified with MWCNTs, then, the gold nanoparticles were pulse deposited on the previous modified electrode, the superoxide anion non-enzymatic electrochemical sensor based on AuNPs/PEDOT-Fe(CN)64-/MWCNTs composite was constructed. The morphology of the composites was investigated thourgh SEM, and the electrochemical behaviors of O2- on the modified electrode were investigated by CV, EIS and i-t.At the same time, the conditions to modify the electrode and to detect O2- were optimized. The results showed that AuNPs/PEDOT-Fe(CN)64-/MWCNTs composite not only effectively reduce overpotential of O2·-, but also increases the reduction current.