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Study On Nonenzymatic Glucose Sensor Modified By Ag/Ag&Pt Based On TiO2 Nanotubes

Posted on:2017-03-18Degree:MasterType:Thesis
Country:ChinaCandidate:Z LiFull Text:PDF
GTID:2308330503457513Subject:Biomedical engineering
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The blood glucose detection is of great significance in the application of food process, clinical medicine and biology. Especially accurate and fast glucose determination for diabetics can be very effective to the detection and treatment of diabetes mellitus. The glucose oxidase(GOD) analytical method owning to high sensitivity and fast current response became the most commonly used way for glucose detection in clinical trials. However, GOD is easily inactive and denatured during the immobilized process, resulting in poor stability and repeatability of enzymatic electrodes, which limited its application. The development of new type nonenzymatic sensor is bringing a new way for diabetics.Nonenzymatic glucose biosensors can avoid that problem because of direct catalyzed oxidation to glucose on the surface of electrode. Fabrication of electrode with excellent electrocatalytic oxidation property was the key to nonenzymatic sensors. In order to increasing activity and stability of constructed biosensors, these electrodes were modified by nano materials like nanotubes, nanowires, nanoflowers, nanoparticles and mesoporous structure etc. for better electronic transfer ability and catalysis owning to the increasing specific surface areas and active sites. In this paper TiO2 nanotubes were prepared via anodic oxidation and Ag nanoparticles were deposited on the nanotubes through in-situ reduction method. The decorated electrode(Ag-TiO2/(500oC))was constructed for glucose detection. It was found that Ag-NPs were remained both inside and outside of TiO2 nanotubes whose length and diameter were about 1.2 μm and 170 nm according to SEM figure, there were more Ag nanoparticles on the TiO2 nanotubes after the annealed process. As shown from the DPV results, the sensitivity of the electrode to glucose oxidation was 3.69 mA*cm-2*mM-1 with a linear range from 20 mM to 190 mM and detection limit of 24 μM(signal-to-voice ratio of 3). In addition the nonenzymatic glucose sensors exhibited good selectivity, stability, reproducibility.Nano bimetallic composite materials were welcomed in recent years because of better electronic properties which dues to synergistic effect of the two metals from each other. Synergistic effect includes electronic and geometric effect which enhances electron transport efficiency and specific surface area, which bring big promotion of conductive and catalytic property. Ag&Pt-Ti O2/(500 oC) electrodes were made via current displacement method based on Ag-TiO2/(500 oC), whose Ag nanoparticles were displaced by Pt nanoparticles, shaping into hollow Pt-Ag structure, which can be seen from SEM photo and proved by TEM figure. This electrode showed excellent oxidative activity to glucose, with a linear range from 30 mM to 210 mM, sensitivity of 4.73 mA*cm-2*mM-1 and limit detection of 19 μM(signal-to-voice ratio of 3) when the correlation coefficient was 0.993 Compared with previous Ag-Ti O2/(500 oC) electrode, Ag&Pt-Ti O2/(500 oC) electrode presented higher peak current, larger sensitivity and longer linear range. Besides, this electrode also showed anti-interference ability to Cl ions and excellent stability, selectivity and stability, providing a new way for application of nonenzymatic sensors.
Keywords/Search Tags:Ti O2 naotubes, nonenzymatic glucose sensor, Ag nanoparticles, hollow Ag&Pt nanoparticles
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