Glucose sensor based upon nanoscale multilayered redox polymers

The authors have fabricated glucose sensors using alternately stacked layers of glucose oxidase (GOX) and polycationic osmium charge mediators. A gold surface was functionalized with negatively charged carboxyl groups using mercaptoundecanoic acid (MUA). The cationic charge mediator was then electrostatically bound to the negatively charged surface, followed by binding of the anionic enzyme. This process was repeated to create a multilayered structure. Current responses were evident upon glucose addition using both cyclic voltammetry and chronoamperometry. Chemical or photochemical crosslinking were utilized to stabilize the multilayer structure and increase the current response. Chemical crosslinking was accomplished via exposure to glutaraldehyde. Photochemical crosslinking was performed using a film composed of an acrylate modified osmium derivative (Os(bpy)z(poly(vinylpyridine))-acrylate) and an acrylated-PEG poly(ethylene glycol) modified GOX. This film was placed in solution with a photoinitiator, 2,2´dimethoxy-2-phenyl-acetophenone (DMPA), allowed to hydrate and exposed with 365 nm UV light to induce crosslinking. PEG was also grafted to the surface of these films to improve biocompatibility. Finally, arrays of these films were generated using micro-contact printing techniques (μCP)