Construction Of Novel Nanogold Biosensor And Preliminary Investigation On DNA Damage

Recently, nanotechnology has been generally penetrated in various traditional subjects, and plays important role in nanoelectronics, nanomaterial, nanochemistry, nanobiology, nanomechanics, and so on. Therefore, this thesis was concentrated on nanogold in biosensor, electrochemistry and photochemistry. On the other hand, cancer is another hotspot, so some pharmaceutical on DNA damage was also investigated in detail. The main work could be summarized as follows:1) Based on the biocompatibility of nanogold, the immobilization of alcohol dehydrogenase on nanogold was investigated using piezoelectric quartz crystal sensor, cyclic voltammetry and electrochemical impedance spectroscopy. The Michaelis-Menten constant and maximum initial reaction rate, the binding constant of alcohol dehydrogenase with nicotinamide adenine dinucleotide was estimated.2) Nanogold was successfully immobilized on gold surface through the thiol groups of 1,6-hexanedithiol, and the existing form of thiol on gold was studied in detail by using piezoelectric quartz microbalance. A cathode peak at 0.486 V was found both on the bare gold electrode and nanoglod modified electrode. The function of different surfactants on the peak at nanogold modified electrode was investigated in detail and the probable mechanism was performed.3) Based on the earlier reports that they usually immobilized nanogold on the electrode and followed by enzyme, on the contrast, enzyme was immobilized at first, and then nanogold was adsorbed using the interaction between nanogold and enzyme to explore the function of nanogold on enzyme reaction. Four kinds of xanthine oxidase biosensor with or without nanogold and with or without Prussian blue were fabricated, and the corresponding analytical performances and Michaelis-Menten constant were studied. At the same time, the relationship between the current response and applied potential was discussed and different possible mechanism was performed.4) Using the above method, another enzyme, horseradish peroxidase was selected to further verify the action of nanogold in enzyme reaction. Similarly, the analytical performance and Michaelis-Menten constant were studied, and the influence of applied potential on current response was discussed and different possible mechanism was performed.5) In the immobilization of nanogold using 1,6-hexanedithiol, some defects were found including the odoriferous smell and hard-to-refresh. Therefore, using the special properties of chitosan, i.e., soluble in many mineral and inorganic acids and insoluble in neutral and basic solutions, chitosan/glutaraldehyde/cysteamine (CGC) membrane were first performed to immobilize nanogold. The immobilization of CGC membrane on gold surface and nanogold on CGC membrane were in situ monitored using piezoelectric quartz crystal impedance, cyclic voltammetry and electro -chemical impedance spectroscopy. Furthermore, the viscosity-average molecular weight of chitosan was firstly estimated using piezoelectric quartz crystal sensor. Nanogold was also used to immobilize human serum albumin, and its binding with purified hesperidin was monitored.6) Due to the tertiary amine structure, pentoxyverine was firstly detected by capillary electrophoresis-electrochemiluminescence (CE-ECL). The experimental conditions and the linear response range were investigated in detail. What's more, the addition of some nanogold can improve the ECL intensity to some degree. The transmission electron microscope and UV-visible spectra were used to explore the properties of nanogold before and after detection.7) Another pharmaceutical, chlorpheniramine, was also firstly detected by CE-ECL. The optimal experimental conditions, the repeatability, and the linear response range were discussed in detail. Under proper conditions, chlorpheniramine, pentoxyverine, and lidocaine can be successfully separated. Nanogold can enhance the ECL intensity without .the change of its properties. At the same time, the dialysis was used to investigate the binding of chlorpheniramine with human serum albumin.8) DNA damage by quercetin -Cu2+ was monitored in real time by piezoelectric quartz crystal impedance (PQCI) technique. In the PQCI analysis, the frequency change was caused mainly by the changes in density-viscosity of DNA solution in the damage course. The influences of DNA, Cu2+, and quercetin concentrations on the motional resistance change (Ai?m) were investigated in detail. The results showed that quercetin exhibited pro-oxidative damage at lower concentrations while anti-oxidative protection at higher concentrations. Potentiometric stripping analysis (PSA) was also used to observe the electrochemical behavior of damaged DNA. From PSA, a new peak at 0.84 V and a higher peak at 1.06 V were discovered, which suggested that more purines were exposed to the electrode surface during the damage course. In agarose-gel electrophoresis, catalase and biquinoline were found to effectively inhibit DNA damage, therefore, a possible damage mechanism was...