Study On Disposable Glucose Oxidase Bienzyme Biosensors

Diabetes mellitus is a common and frequently-occurring disease, which seriously menaces the healthy of the human beings. Presently, there are about fifty million diabetic people in our country. Therefore, the diagnosis and treatment of diabetes mellitus is an important task. Glucose is one of the most essential chemical substances in human body. When a total of partial lack of insulin happens, one will suffer from diabetes mellitus, characteristic of high glucose content in blood and urine. So, for the diabetic preventment and treatment, the inspect and monitor of blood sugar timely is an absolutely necessarily way. Besides, glucose also exists extensively in medicament, foods, beverage, feeds and even the environmet we lives. Therefore, glucose analysis and detection has great significance. In this paper, the nanoparticles were used in the fabrication of biosensors. Combining self-assembled monolayers (SAMs) and sol-gel technology, this thesis concerns three research sections:First, the gold nanoparticles (AuNPs) were electrodeposited on the indium tin oxide (ITO) electrode surface, and then the glucose oxidase (GOD) was immobilized on the AuNPs/ITO electrode to fabricate the GOD/Cys/AuNPs/ITO electrode. The prepartion conditions of the enzyme electrode were optimized. The immobilized GOD exhibited direct electrochemical behavior toward the glucose. The heterogeneous electron transfer rate constant (ks) was evaluated to be 3.7 s-1. The calibration range of glucose content was from 0.04 mM to 4.8 mM. The apparent Michaelis-Mentien constant (KMapp) value of GOD immobilized on the electrode surface was found to be 12.07 mM. The electrode maintained 85% of its original current response after 30 days.Second, sol-gel method was applied for fabrication of GOD-Cys-SG/AuNPs/ITO electrode. The dirct electron transfer between GOD and AuNPs/ITO electrode surface was realized. The electrochemical behaviors of the electrode were studied and it was used to detect the glucose contentration. The ks was evaluated to be 3.7 s-1 and the calibration range of glucose content was from 0.04 mM to 4.8 mM. The KMapp value of GOD immobilized on the electrode surface was found to be 12.07 mM. The current response only reduced 8% of its original current after 30 days.Third, on the basis of SAMs and sol-gel methods for fabrication of GOD biosensors, the GOD-HRP-Cys-SG/AuNPs/ITO bienzyme electrode was fabricated with sol-gel method. The sol-gel method is easy to control the content of the two enzymes, thus optimize the prepartion conditions. The electrocatalytial ability was enhanced largely and the the calibration range of glucose content was from 0.02 mM to 3.2 mM. The current response only reduced 10% of its original current response after 30 days. The biezyme electrode shows high sensitivity, excellent reproducibility and high selectivity.Due to its good conductive properties and low cost, AuNPs modified ITO electrode is a good substrate to immobilize GOD enzyme. It is ezsy and the biosensors can be manufactured in large. Three kinds of disposable biosensors were fabricated using ITO electrode as the substrate.