Development of single-wall carbon nanotubes modified screen-printed electrode using a ferrocene-modified cationic surfactant for amperometric glucose biosensor applications

The application of electrodeposited single-wall carbon nanotubes (SWCNT) as an immobilization matrix for the construction of amperometric glucose biosensor is described. The surface of an electrode was modified by addition of SWCNT and glucose oxidase (GOD), the latter of which was immobilized using 11-(ferrocenyl)-undecyltrimethylammonium bromide (FTMA); the formation and disruption of vesicles in FTMA was controlled by constant potential electrolysis. SWCNT has promotion effects on the direct electron transfer of GOD, which was immobilized with SWCNT. The cyclic voltammetric results indicated that direct electron transfer between the active center of immobilized GOD and the surface of the electrode occurred. The electron-transfer coefficient was 0.70 ± 0.3 and electron-transfer rate constant was evaluated to be 2.69 ± 0.03 s−1. This modified electrode was used to measure d-glucose concentration; a linear relationship between steady-state current and concentration was found over a range of 0.04–0.38 mM d-glucose, with a slope of 1.73 μA/mM, and the electrode retained 78.62% of its initial response after 50 cycles. The variation coefficient was 10.6% (n = 10) for samples with a d-glucose concentration of 0.04 mM. Even after 42 days, the residual activity of the modified electrode was over 94%, and it was still useful for determination of d-glucose.