We describe in detail the different steps involved in the construction of a carbon nanotube field-effect transistor (CNTFET) based on a network of single-walled carbon nanotubes (SWCNTs), which can selectively detect human immunoglobulin G (HIgG). HIgG antibodies, which are strongly adsorbed onto the walls of the SWCNTs, are the basic elements of the recognition layer. The nonspecific binding of proteins or other interferences are avoided by covering the nonadsorbed areas of the SWCNTs with Tween 20. The CNTFET is a reagentless device that does not need labels to detect HIgG.
