A Study on Glucose Sensing Measured by Catalyst Containing Multiple Layers of Glucose Oxidase and Gold Nano Rod

In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ((GOx/GNR)nPEI/CNT). To investigate the impact of (GOx/GNR)nPEI/CNT on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that (GOx/GNR/ PEI)2/CNT is the best layer. Its glucose sensitivity is 13.315 μAmM -1 cm -2 . When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within (GOx/GNR/PEI)2/CNT, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the (GOx/GNR/PEI)3/CNT is limited to the surface reaction and the reaction is quasi-reversible.