An Oxygen Insensitive Amperometric Glucose Biosensor Based on An Engineered Cellobiose Dehydrogenase: Direct versus Mediated Electron Transfer Responses

Abstract

AbstractCellobiose dehydrogenase (CDH) is capable of oxidizing cellobiose and related carbohydrates and generating electrical current at carbon‐based electrodes through direct electron transfer (DET) or mediated electron transfer (MET) mechanisms. As a result, CDHs have been utilized as biocatalysts in biosensors and biofuel cell anodes. A novel engineered ascomycetous Class II CDH with enhanced glucose activity was tested as a bioelectrocatalyst for application to DET or MET‐based glucose biosensors with the electrode component amount selection optimized for maximum current in 5 mM glucose solutions. The optimised DET biosensor showed a similar sensitivity and 3‐fold lower KM,app when compared to non‐optimised DET sensor based on the same engineered CDH. The optimized MET biosensor had a similar KM,app to non‐optimized MET biosensor. However, it showed 15‐fold improvement in jmax and 17‐fold improvement in sensitivity over the DET biosensor. The sensor signals are not affected by the presence of oxygen, although operation in artificial serum results in 43 % and 28 % lower sensitivity for the DET and MET sensors, respectively. While no individually tested potential interferent breaches a mean absolute relative difference of 20 % of the current, the cumulative co‐operative effect in complex media, such as artificial serum, decreases the glucose oxidation current signal.