Investigation On Electrochemical Biosensors Based On Four Kinds Of Carbon-Nanocomposite Materials

Preparation of carbon-nanocomposite materials with excellent properties in construction of high selective and sensitive electrochemical biosensor has already become one of the research subjects for analysts. In this thesis, four kind’s novel electrochemical biosensors were fabricated based on carbon-nanocomposite materials with excellent properties, after which the electrochemical and electrocatalytic behaviors of the hemoglobin (Hb), glucose oxidase (GOD) and horseradish peroxidase (HRP) were studied in details and the new methods for determination of glucose and H2O2were developed. These studies not only can provide the basis for design new electrochemical biological sensing interface and the biological molecular devices, but also expand the scope of carbon-nanocomposite materials applications in the field of bio-electrochemistry. The thesis was divided into three chapters and the main contributions are as follows:1. A review on the application of carbon-nanomaterials in electrochemical biosensors and the research progress of biocatalysis electrochemical biosensor was presented, and the content of the dissertation was proposed with97referenees.2. A novel H2O2biosensor based on the designed carboxyl functionalized polystyrene/graphene-carbon nanotube-Nafion composite film (PS/GE-CNT-Nafion) was fabricated and the direct electrochemistry and electrocatalysis of Hb at the composite film was investigated. The results showed that the biosensor displayed a pair of well-defined, quasi-reversible redox peaks with the formal potential (E0) of-0.249V (vs. SCE), and the electron transfer rate constant (ks) was estimated to be6.2s-1. The proposed biosensor exhibited an electrocatalytic activity to the reduction of H2O2, and the peak currents were linearly related to H2O2concentration in a wider linearity range from5.0×10-7to1.4×10-3M, with a detection limit of2.0×10-1M (S/N=3). The sensitivity and the apparent Michaelis-Menten constant (KMapp) were determined to be59μA·mM-1and8.3×10-3M, respectively. 3. A novel glucose biosensor based on the designed titanium carbide-Au nanoparticles-fullerene composite film modified electrode (TiC-AuNPs-C60/GCE) was fabricated and its biosensing for glucose were investigated. The results showed that the biosensor displayed a pair of well-defined, quasi-reversible redox peaks with the E0of-0.484V (vs. SCE), and the ks was estimated to be4.4s-1The proposed GOD biosensor exhibited an electrocatalytic activity to the reduction of glucose, and the currents of glucose reduction peak were linearly related to glucose concentration in a wider linearity range from5.0×10-6to1.6×10-4M, with a detection limit of2.0×10-6M (S/N=3). The sensitivity and KMapp were determined to be1.5×102μA·mM-1·cm-2and6.2×10-5M, respectively.4. Polyvinylpyrrolidone-graphene-poly-p-phenylenediamine composite materials (PVP-GE-PpPD) were prepared through in situ reduction reaction and a novel glucose biosensor based on GOD biocatalyzed deposition of Au nanoparticles (AuNPs) on the designed template was described. The studies showed that the oxidation peak currents of AuNPs were linearly related to glucose concentration in a wider linearity range from5.0×10-1to2.0×10-4M, with a detection limit of2.0×10-7M (S/N=3). The sensitivity was determined to be3.4×102μA·mM-1·cm-2.5. Graphene-carbon nanotube-Nafion/gold-platinum alloy nanoparticles (GE-CNT-Nafion/AuPt NPs) was prepared by in situ reduction reaction and electrochemical deposition, and a novel H2O2biosensor based on HRP induced deposition of polyaniline (PANI) on the designed composite film was fabricated. The studies showed that the biosensor displayed a pair of well-defined redox peaks of PANI, and the reduction peak currents of PANI measured by square wave voltammetry were linearly related to H2O2concentration in a wider linearity range from5.0×10-7to1.0×10-4M, with a detection limit of1.7×10-7M (S/N=3). The sensitivity was determined to be3.7×102μA·mM-1. The biosensors were constructed by using biocatalytic reaction for inducing the accumulation of nanoparticles had a simple, good selectivity and sensitivity.