A novel glucose biosensor based on immobilization of glucose oxidase into multiwall carbon nanotubes–polyelectrolyte-loaded electrospun nanofibrous membrane

Nanofibrous glucose electrodes were fabricated by the immobilization of glucose oxidase (GOx) into an electrospun composite membrane consisting of polymethylmethacrylate (PMMA) dispersed with multiwall carbon nanotubes (MWCNTs) wrapped by a cationic polymer (poly(diallyldimethylammonium chloride) (PDDA)) and this nanofibrous electrode (NFE) is abbreviated as PMMA–MWCNT(PDDA)/GOx–NFE. The NFE was characterized for morphology and electroactivity by using electron microscopy and cyclic voltammetry, respectively. Field emission transmission electron microscopy (FETEM) image reveals the dispersion of MWCNT(PDDA) within the matrix of PMMA. Cyclic voltammetry informs that NFE is suitable for performing surface-confined electrochemical reactions. PMMA–MWCNT(PDDA)/GOx–NFE exhibits excellent electrocatalytic activity towards hydrogen peroxide (H2O2) with a pronounced oxidation current at +100 mV. Glucose is amperometrically detected at +100 mV (vs. Ag/AgCl) in 0.1 M phosphate buffer solution (PBS, pH 7). The linear response for glucose detection is in the range of 20 μM to 15 mM with a detection limit of 1 μM and a shorter response time of ∼4 s. The superior performance of PMMA–MWCNT(PDDA)/GOx–NFE is due to the wrapping of PDDA over MWCNTs that binds GOx through electrostatic interactions. As a result, an effective electron mediation is achieved. A layer of nafion is made over PMMA–MWCNT(PDDA)/GOx–NFE that significantly suppressed the electrochemical interference from ascorbic acid or uric acid. In all, PMMA–MWCNT(PDDA)/GOx–nafion–NFE has exhibited excellent properties for the sensitive determination of glucose like high selectivity, good reproducibility, remarkable stability and without interference from other co-existing electroactive species.