title: Label-free as-grown double wall carbon nanotubes bundles for Salmonella typhimurium immunoassay.
abstract: BACKGROUND
  A label-free immunosensor from as-grown double wall carbon nanotubes (DW) bundles was developed for detecting Salmonella typhimurium. The immunosensor was fabricated by using the as-grown DW bundles as an electrode material with an anti-Salmonella impregnated on the surface. The immunosensor was electrochemically characterized by cyclic voltammetry. The working potential (100, 200, 300 and 400 mV vs. Ag/AgCl) and the anti-Salmonella concentration (10, 25, 50, 75, and 100 μg/mL) at the electrode were subsequently optimized. Then, chronoamperometry was used with the optimum potential of 100 mV vs. Ag/AgCl) and the optimum impregnated anti-Salmonella of 10 μg/mL to detect S. typhimurium cells (0-10(9) CFU/mL).
  
  
  RESULTS
  The DW immunosensor exhibited a detection range of 10(2) to 10(7) CFU/mL for the bacteria with a limit of detection of 8.9 CFU/mL according to the IUPAC recommendation. The electrode also showed specificity to S. typhimurium but no current response to Escherichia coli.
  
  
  CONCLUSIONS
  These findings suggest that the use of a label-free DW immunosensor is promising for detecting S. typhimurium.
authors.affiliation: School of Agro-Industry, Mae Fah Luang University, Chiang Rai 57100, Thailand.
authors.forename: Niramol
authors.initials: N
authors.lastname: Punbusayakul
authors.affiliation: Department of Physics, Southern Illinois University Carbondale, Carbondale, IL 62901, USA.
authors.forename: Saikat
authors.initials: S
authors.lastname: Talapatra
authors.affiliation: Department of Mechanical Engineering & Materials Science, Rice University, Houston, TX 7705, USA.
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.affiliation: School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
authors.forename: Werasak
authors.initials: W
authors.lastname: Surareungchai