Carbon fiber nanoelectrodes modified by single-walled carbon nanotubes

Microelectrode voltammetry has been considered to be a powerful technique for single biological cell analysis and brain research. In this paper, we have developed a simple method to get highly sensitive carbon fiber nanoelectrodes (CFNE) modified by single-walled carbon nanotubes (SWNTs) on the basis of our previous work. The electrochemical behavior of SWNTs/CFNE was characterized by potassium ferricyanide, dopamine (DA), epinephrine (E), and norepinephrine (NE) using cyclic voltammetry (CV). Compared with CFNE, SWNTs/CFNE has a much larger available internal surface area per external geometric area, which is supported by SEM images. The modified electrodes show very high sensitivity and favorable electrochemical behavior toward these neurotransmitters. The peak current increases linearly with the concentration of DA, E, and NE in the range of 1.0 x 10(-7)-1.0 x 10(-4), 3.0 x 10(-7)-1.0 x 10(-4), and 5.0 x 10(-7)- 1.0 x 10(-4) M, respectively. The CV detection limit (S/N = 3) of DA, E, and NE is 7.7 x 10(-9), 3.8 x 10(-8), and 4.2 x 10(-8) M, respectively. The modified electrode exhibited almost the same electrochemical behavior after 15 days, indicating that SWNTs/CFNE is pretty stable and has good reproducibility.