Cellobiose dehydrogenase/ epoxy-graphite composite with aryl diazonium reduction for lactose detection

Abstract

Milk is an important ingredient in our day to day diet bacause of the high quality nutrients in it. In the dairy industry including cheese fermentation processes, there is a need to control the release of lactose into wastewater streams. There are methods adopted to recover the lactose and to transform the lactose into energy through renewable energy (RE) pathways. These methods however are expensive and require certain skill to operate them. In this study, in-house electrode, which is simple and can be applied after one day of fabrication were investigated. The method was by using graphite-epoxy composite electrode, surface modified with cellobiose dehydrogenase (CDH) enzyme using aryl diazonium. These designed composite electrodes were tested on its capability as biosensor for sensitivity on detecting the lactose as well as its capability as an anode in enzymatic fuel cell (EFC) on long term electrochemical stability in generating electricity from lactose oxidation. The results showed that the CDH-Aryl diazonium modified on surface of fabricated graphite-epoxy electrodes had Michaelis Menten constant Km for CDH (0.65 – 0.75 mM) comparable to available commercial electrodes reported in the literature (0.7 mM). They are also conductively sensitive with the current intensity 86% more with the above mentioned electrodes when modified with embedded multi-walled carbon nanotube (MWCNT) and gave a high reproducibility signal (63% more than fabricated electrodes without MWCNT). In addition to the above, its performance stability in continuous mode operation for 25 days, recorded almost consistent in current detection (19.2 ± 3.8 µA/ cm2). Hence, these fabricated electrodes give alternative for a sensitive lactose detector which is cheap and simple to fabricate.