Direct electron transfer from glucose oxidase immobilized on polyphenanthroline-modified glassy carbon electrode

This study reports direct electron transfer (DET) from immobilized glucose oxidase (GOx) via grafted and electropolymerized 1,10-phenanthroline monohydrate (PMH). The layer of poly-1,10-phenanthroline (PPMH) was gained via electrochemical deposition, which was used to create the PPMH-modified GC-electrode (PPMH/GC-electrode). Further, the GOx was immobilized on the PPMH/GC-electrode. The effect of surface-modification by the PPMH on the electron-transfer between enzyme and electrode-surface and some other electrochemical/analytical-parameters of newly designed enzymatic-electrode were evaluated. The PPMH/GC-electrode showed superior DET to/from flavine adenine dinucleotide cofactor of GOx, while some redox-compounds including ferrocene and K3[Fe(CN)6] were completely electrochemically inactive on the PPMH/GC-electrode. It was also found that the resulting GOx/PPMH/GC-electrode functioned as a “direct response type” glucose-biosensor. The biosensor showed excellent selectivity towards glucose and demonstrated good operational-stability. According to our best knowledge, this study is the first scientific report on electrochemical-polymerization of PMH on the GC-electrode in non-aqueous media followed by its application in the design of glucose-biosensor. -

Keywords: Surface-modification; Phenanthroline; Glucose oxidase; Biosensor; Electron transfer; Electrocatalysis