Functionalized multi-walled carbon nanotubes/polyvinyl alcohol membrane coated glassy carbon electrode for efficient enzyme immobilization and glucose sensing

Enzyme catalyzed reactions have been considered to be friendly and thus “green” for the environment. The two main requisites for developing an enzyme based amperometric sensor for biomedical as well as industrial applications are a robust support for the enzyme and an efficient conduit for electron conduction. Keeping in view the aforementioned requirements, we designed an electrode using selectively functionalized multi-walled carbon nanotube dispersed in polyvinyl alcohol (PVA-MWCNT) matrix. Glucose oxidase (GOx) enzyme was immobilized on this electrode and glucose concentration was monitored to determine the efficiency of the (PVA-MWCNT) membrane coated glassy carbon electrode. The load of GOx immobilized on the membrane achieved was as high as 3.98 × 10−9 mol/cm2. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used as an analytical tool to show immobilized GOx enzyme. The electron transfer rate constant (ks) of the modified glassy carbon electrode obtained by cyclic voltammetry measurements was 1.58 s−1 which shows a rapid electron transfer process and high sensitivity of 8.67 mA mM−1 cm−2 indicating a better response as compared to the values reported till now. This is the first report of such high load of enzyme on functionalized PVA which contributes to the enhanced electron conduction leading to the detection of glucose over a wider linear range of 0.1-20.0 mM. Detection limit of the electrode for glucose is 0.15 mM.