Fabrication of electrochemical bio-sensors for the detection of glucose and hydrazine using ZnO nanonails grown by the thermal evaporation process

摘要

Well-crystallized zinc oxide nanonails have been synthesized in a large quantity via a thermal evaporation method using the metallic zinc powder without the use of any metal catalyst or additives. The detailed structural and optical characterizations confirmed that the as-synthesized nanonails are single-crystalline with the wurtzite hexagonal phase, grown along the [0001] direction and possessing a good optical properties. For applications point of view, the as-grown ZnO nanonails were used as supporting matrixes for enzyme immobilization, glucose oxidase (GOx), to construct efficient glucose biosensors. The ZnO nanonails have a high surface area and presenting themselves as an efficient electron conducting tunnel, so the GOx attached to the surfaces of ZnO nanonails had more spatial freedom in its orientation, which facilitated the direct electron transfer between the active sites of immobilized GOx and electrode surface. A high sensitivity, 24.613 μA cm~(-2) mM~(-1), with a response time less than 10s was achieved from the fabricated glucose biosensor. The biosensor shows a linear range from 0.1 to 7.1 mM with a correlation coefficient of R= 0.9937 and the detection limit of 5 μM. Moreover, the detection of hydrazine was performed in a phosphate buffer (pH 6.6). The peak current increases linearly with the concentration of hydrazine from 0.01 to lmM. This work demonstrates that the ZnO nanostructures can be utilized as an efficient electron mediator to fabricate efficient biosensors.