Plasma thiol-functionalized carbon nanotubes decorated with gold nanoparticles for glucose biosensor

Abstract

For the first time, MWCNTs were thiol functionalized using dielectric barrier discharge plasma in the presence of H2S/He at room temperature and atmospheric pressure. At the optimum plasma conditions, maximum amount of 0.57wt.% thiol groups was formed on the surface of MWCNTs. The deposition-precipitation method was used to decorate MWCNTs with Au-nanoparticles. TEM, FE-SEM, FTIR, Raman, Ellman reagent method, XRD and cyclic voltametry were used to characterize the samples.A glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on the Au/MWCNTs hybrid. The redox process of the GOx/Au/MWCNTs hybrid electrode was shown to be reversible and surface-controlled process in 0.1M phosphate buffer solution at pH 7.0. The charge transfer coefficient and charge transfer rate constant for electron transfer between GOx and the electrode surface were calculated as 0.48 and 1.13s−1, respectively. The GOx/Au/MWCNT-modified electrode exhibited a linear behavior in the range of 0.4–4.0mM glucose with detection limit of 3.0μM and sensitivity of 23.1μA/mMcm2. The modified electrode retained more than 58% of its initial faradic current value after 50 days.