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

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 0.57 wt.% 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. ose 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 0.1 M 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 1.13 s−1, respectively. The GOx/Au/MWCNT-modified electrode exhibited a linear behavior in the range of 0.4–4.0 mM glucose with detection limit of 3.0 μM and sensitivity of 23.1 μA/mM cm2. The modified electrode retained more than 58% of its initial faradic current value after 50 days.