Figure 5.

Schematic illustration of the label-free immunosensors using single-walled carbon nanotubes (SWCNTs). SWCNTs were grown directly on the platinum electrode surface. Upon the covalent attachment of the antibodies on the SWCNTs, a current response is recorded from the intrinsic electro-activity of the antibodies. As the antigens are bound with the antibodies, the electrochemical responses change. The current height at the peak oxidation potential (∼0.5 V vs. Ag/AgCl) increases or decreases depending on the concentration of the bound antigens.