Sub-attomolar detection of cholera toxin using a label-free capacitive immunosensor

Biosens Bioelectron. 2010 Apr 15;25(8):1977-83. doi: 10.1016/j.bios.2010.01.020. Epub 2010 Jan 25.

Abstract

A label-free immunosensor for the direct detection of cholera toxin (CT) at sub-attomolar level has been developed based on potential-step capacitance measurements. Anti-CT antibody was adsorbed on gold nanoparticles (AuNPs) incorporated on a polytyramine-modified gold electrode. The concentration of CT was determined by detecting the change of capacitance caused by the formation of antibody-antigen complexes. By using AuNPs adsorbed to the sensing surface, the signal was dramatically increased leading to a significantly more sensitive assay. In fact, under optimum conditions the immunosensor could detect CT concentration with a limit of detection of 9 x 10(-20)M or 0.09 aM, with a dynamic range between 0.1 aM and 10 pM. Good analytical reproducibility could be obtained by injecting CT up to 36 times with an RSD of 2.5%. In addition, good performance of the developed immunosensor was achieved when applied to turbid water samples collected from a local stream that were spiked with CT.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / chemistry*
  • Antibodies, Bacterial / immunology
  • Biosensing Techniques / instrumentation*
  • Cholera Toxin / analysis*
  • Cholera Toxin / chemistry
  • Cholera Toxin / immunology
  • Conductometry / instrumentation*
  • Electric Capacitance
  • Equipment Design
  • Equipment Failure Analysis
  • Immunoassay / instrumentation*
  • Microchemistry / instrumentation*
  • Nanotechnology / instrumentation*
  • Reproducibility of Results
  • Sensitivity and Specificity

Substances

  • Antibodies, Bacterial
  • Cholera Toxin