Fabrication And Properties Of Single-use Glucose Biosensor Enhanced By Nanoparticles

Diabetes meliitus is a common and frequently occurring disease, which seriously menaces the healthy of the human being .Therefore, the diagnosis and treatment of diabetes meliitus is a heavy responsibility for the biomedical engineering field of the world. Long term clinic investigation indicates that diabetes mellitus and the intercurrent disease could be controlled if blood glucose is controlled in the natural physiological range. The electrochemical glucose biosensor is the major technique for glucose analyses in clinical practice, for the advantages of glucose biosensors are obvious: high specificity, short time, simplicity and low cost of analysis, etc.The portable devices provide a convenient and rapid method for the patient to measure the blood glucose at any moment and everywhere. But the portable blood glucose devices on sale are usually test-paper type devices based on the colorimetry, which are not precise enough. So, it is very necessary to prepare new single-use glucose biosensor with hight sensitivity.In the present thesis, water-soluble polymer (Polyacryamide) layer was used to embed . glucose oxidase (GOD). The effect of the Polyacryamide concentration on the response of enzyme electrodes was discussed., and the solubility of the Polyacryamide was investigated by determining the response electric current of remained GOD in the electrode. 2% Polyacryamide solution is chosen as immobilizing material . The response electric current of the biosensor without nanoparticles linearly rises with the increasing concentration of glucose in the range of 50-400mg/dl .The response sensitivity is 69nA/(mmol/L).Nanoparticles have the excellent characteristics such as the surface effect, the volume effect, etc, which have been used to improve the response sensitivity of the long term biosensor. But its response is unstable after several times use . Nanoparticles was introduced into the single-used glucose biosensor, which showed high sensitivity enhanced by nanoparticles andavoided the unstability of the performance resulting from the leakage of GOD. As a result, at the linear range 50-400mg/dl, the response current of Au nanoparticles enhanced glucose biosensor obviously increases; and the response sensitivity is 112nA/(mmol/L), that is 1.0 times than that without nanoparticles. The effect of the amount of hydrophilic Au nanoparticles added on the response of enzyme electrodes was investigated, and the addition of lOul nanoparticles is considered as the best.Ag nanoparticles enhanced biosensors were studied by the addition of different size particles. The performance of sensor enhanced by 20nm Ag nanoparticles is better. The response sensitivity is 82nA/ (mmol/L).But its performance is poor compared with that enhanced by hydrophilic Au nanoparticles. The addition of nanoparticles decreases the working-potential.The effect of the nanoparticles on the activity of GOD was investigated. The hydrophilic Au nanoparticles show better results on keeping the activity of GOD compared with the Ag nanoparticles. The effect of the Ag nanoparticles on the activity of GOD is related to the particle size. The smaller nanoparticles, the better GOD activity. In addition, the effect is related to the oxidation of Ag nanoparticles, and the oxidized Ag nanoparticles hasn't obvious enhanced effect on GOD activity.