Carbon nanotube based electrochemical immunosensors for high-sensitive detection of E. coli

This paper outlines the fabrication and characterization of an immunosensor based on electrochemical, biological, and nano-material techniques to achieve high sensitive detection of Escherichia coli (E.coli). The working electrode consists of E.coli antibody/antigen/horse-radish peroxidase (HRP) labeled antibody immobilized on plasma-functionalized multiwalled carbon nanotube (pf-MWCNT) film. Immunosensors were characterized by cyclic voltammetry using 10 mM K₃Fe(CN)₆/3 M KCl and 3, 3´, 5, 5´-tetramethylbenzidine (TMB). This immunosensor shows very high sensitivity to E. coli O157:H7 and detection limit as low as 0.031 ng/ml. This is 100 times lower than that achievable with standard spectrophotometric enzyme-linked immunosorbent assay (ELISA) using the same immunochemicals.