Gluocose And Superoxide Anion Electrochemical Biosensor Research

Diabetes and aging, the two general healthy problems in the world, have received great attention. Therefore, the detection of the glucose in blood and the reactive oxygen species in vivo become much urgent and important. The electrochemical method because of its easy preparation, low cost, high sensitivity, excellent selectivity, stability and reproducibility, has wide applications in the biosensors. Since the characteristics of the electrochemical biosensors greatly rely on the materials modified on the electrodes, in order to improve the performance of the biosensor, developing suitable electrode materials is one of the most interesting projects. The previous studies have shown that some noble metal nanomaterials, like platinum, gold and palladium, not only possess good biocompatibility, but also can catalyze the electrochemical performance of the bimolecules. With the increasing study of the carbon nanotubes, various kind of carbon nanomaterials have been also applied in the electrochemical biosensors. Based on these facts, we have carried out several studies in glucose and superoxide anion electrochemical biosensors using different nonomaterial modified electrodes. Moreover, the morphology and electrochemical characteristics of these nanomaterials have been discussed through the traditional methods. The main points of this thesis are as follows:(1) By direct polymerization of ionic liquid on the outside wall of the carbon nanotubes (CNTs), the platinum nanoparticles were dispersed on the surface of CNTs and PtNPs/PIL-CNTs nanoohybrids were obtained and applied in the construction of glucose amperometric sensors. The morphology of the nanohybrids was investigated thourgh the Transmission electron microscopy (TEM), and the catalytic activity of this nanocomposite toward H2O2 oxidation was evaluated by cyclic voltammetry (CV) and amperometry (i-t). It can be found that PtNPs and CNTs have synergies effect toward the catalytic oxidation of hydrogen peroxie. Based on this, we successfully constructed a new glucose amperometric biosensor and directly applied this sensor to the detection of the concentration of the glucose in the human blood.(2) Based on the fact that chitosan can only dissolve in acidic environment, a uniform nanoporous gold film (NPGF) has been obtained by square wave voltammetry deposition method in the solution of chlorauric acid and chitosan and then applied in the fabrication of the third-generation superoxide anion biosensor. The morphology and the composition of the NPGF were studied by scanning electron microscopy (SEM) and energy dispensive spectroscopy (EDS). And the direct electrochemical reaction of superoxide dismutase on this modified electrode was investigated by CV and electrochemical impedance spectroscopy (EIS). The results show that the large surface area and better catalytic activity of the NPGF have significantly enhanced the direct electron transfer between the superoxide dismutase and the electrode. The resulted biosensor exhibits excellent characteristics.(3) The hollow nitrogen-doped carbon microsphere (HNCMS) was synthesized by using silica as the template and dopamine as the resource of carbon and nitrogen. Then palladium was deposited on the HNCMS to prepare PdNPs/HNCMS catalyst which were successfully applied in the glucose nonenzymetic biosensor. The morphology and the composition of the NPGF were studied by TEM and EDS. The catalytic activity of this nanocomposite toward glucose oxidation was evaluated by CV and i-t. The results show that this material can not only shift negatively the oxidation potential of glucose, but also make the direct oxidation of glucose carry out easily. On the other hand, we investigated the oxidation current of glucose as well as different interferents under different potentials. The obtained nonenzymetic glucose electrochemical biosensor has good selectivity and high sensitivity, which make the possibility for commercialization of the nonenzymetic biosensor.