“…In recent years, the electrochemical immunoassays have been developed based on nanomaterials, such as colloid gold (Xiao & Yu, 2010), nano-SiO 2 (Tang, Su, Tang, Ren & Chen, 2010;Wu, Chen & Liu, 2009), nano-TiO 2 (Wang, Ruan, Kanayeva, Lassiter & Li, 2008), nano-Ag (Loyprasert et al, 2008), carbon nanotube (Diakowski, Xiao, Petryk & Kraatz, 2010), Fe 3 O 4 nanoparticles (Huang et al, 2010), and nano-Pt (Huang, Wen, Jiang, Shen & Yu, 2008), all of which have attracted considerable interest in biosensor development. Among the nanomaterials mentioned above, gold nanoparticles, which have good characteristics of easy preparation, good biocompatibility and relatively large surface, are widely used to immobilize DNA (Li, Feng, Dong & Tang, 2010;Zhang, Wang & Xu, 2010), cell (Yan, Chen & Ju, 2007), cytochrome (Bonk & Lisdat, 2009;Li et al, 2009), and enzyme (Kim, Kang, Shim & Moon, 2008;Wang, Wang, Di & Tu, 2008) in the field of biological studies. Recently, gold nanoparticles have been used to immobilize the antigen or antibody onto the electrode surface to manufacture the electrochemical immunosensors (Valera, Muñiz & Rodríguez, 2010;.…”