A salivary glucose biosensor based on immobilization of glucose oxidase in Nafion-carbon nanotubes nanocomposites modified on screen printed electrode

Due to unhealthy lifestyles, the population of diabetics is rapidly increasing, therefore, the demand of glucose meter is also increasing. However, not all the people could overcome the fear of jabbing a needle during blood glucose tests. In this regard, we report a non-invasive glucose sensing electrode composed of conductive and bio-compatible Nafion-carbon nanotubes (Nf-CNT) nanocomposite and glucose oxidase (GOx), which are sequentially coated on screen-printed electrode (SPE). The Nf-CNT nanocomposite is prepared through ultrasonication followed by drop casting it onto the SPE. Subsequently, Nf-CNT/SPEs are subjected to plasma treatment followed by drop-casting of GOx to fabricate GOx/Nf-CNT/SPE electrodes. The plasma treatment alters the hydrophobic nature of Nf-CNT/SPE, which not only exposes the surface of Nf-CNT layer, but also enables it for uniform coating of GOx. The results confirm that the mixing ratio of Nafion and CNT as well as plasma treatment time significantly affects sensing performance. The GOx/Nf-CNT/SPE subjected to 1 min of plasma treatment prior to the coating of GOx shows the best performance with a sensitivity of 99.13 μA/mMcm2 and a linear range of 20–700 μM. Moreover, the GOx/Nf-CNT/SPE electrodes are also tested under artificial saliva, which shows their high potential in the diagnosis of diabetes.