Single-Walled Carbon Nanotube Films (SWNTs) for Biosensing Applications

Amperometric biosensors were constructed by a two step procedure. In the fist step, a thin SWNT film was formed on a glassy carbon electrode surface by solution casting of a dispersed SWNT solution.  The SWNT film was then coated with a redox polymer/enzyme hydrogel. The influences of (i) the SWNT solution dispersed by different surfactants (water, Triton X-100, Sodium cholate); (ii) different redox polymers (PVP-OS, Fc-C6-LPEI, Fc-C3-LPEI), and (iii) enzymes (GOx, HRP) on the electrochemical and enzymatic response were investigated by cyclic voltammetry, constant potential amperometry,  and electrochemical impedance spectroscopy. The results showed that, for the three redox polymer/GOx based biosensors, the type of surfactant used to form the initial SWNT film was a critical factor in determining whether the sensors produced a significant increase (～2.5 mA/cm²) or decrease (～0.1 mA/cm²) of the enzymatic response to glucose.