Journal
BIOSENSORS & BIOELECTRONICS
Volume 25, Issue 8, Pages 1977-1983Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2010.01.020
Keywords
Label-free immunosensor; Attomolar; AuNPs; Cholera toxin; Capacitance
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Funding
- VR (The Swedish Research Council)-SIDA
- Thailand Research Fund, Center of Excellence for Innovation in Chemistry (PERCH-CIC)
- Ministry of Education
- Trace Analysis and Biosensor Research Center (TAB-RC)
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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. (c) 2010 Elsevier B.V. All rights reserved.
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