Development of a reagentless electrochemical glucose sensor

In this work, developing a reagentless electrochemical glucose sensor by immobilizing the wild type enzyme onto semi-conductor silicon chips as well as screen-printed carbon electrodes, was attempted. In the first immobilization procedure, the substrates were modified with nitrobenzenediazonium and glutaraldehyde. The electrodes were then put in contact with a glucose solution. The changes introduced to the surface were monitored using impedance measurements, which show that the enzyme was successfully immobilized, but its active site seems to be unavailable for glucose binding. In the second immobilization procedure, the substrates were modified with an amine terminated NTA ligand. This was done by trying to generate and reduce an in-situ diazonium moiety, after reaction with NaNO 2 . This approach failed because there was no aniline moiety in the ligand, which according to literature, is crucial. In the last immobilization procedure, the substrates were oxidized in the presence of 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and then the NTA ligand was added. Electrodes were then loaded with nickel cations. The glucokinase was tagged with a 6-histidine tail, which was expected to coordinate to Ni 2+ , thus ensuring the availability of the active site. Results indicated that the electrodes were successfully modified and showed to be sensitive to the presence of glucose