Gold nanoparticles based sandwich electrochemical immunosensor

In this report we have used gold nanoparticles (AuNPs) to covalently attach an antibody (Ab 1) using a spacer arm. The AuNPs/Ab 1 modified gold electrode was used for a sandwich electrochemical immunoassay. The detection was done using cyclic voltammetry and impedance measurements using Horse Radish...

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Bibliographic Details
Published in:Biosensors & bioelectronics 2010-05, Vol.25 (9), p.2016-2020
Main Authors: Ahirwal, Gautham Kumar, Mitra, Chanchal K.
Format: Article
Language:English
Subjects:
Animals
Antibodies
Antigen-Antibody Complex
Benzidines
Biological and medical sciences
Biosensing Techniques
Biosensor
Biosensors
Biotechnology
Chromogenic Compounds
Electric Impedance
Electrochemical immunoassay
Electrochemical Techniques
Fundamental and applied biological sciences. Psychology
Gold
Gold nanoparticles
Horseradish Peroxidase
Humans
Immunoassay - methods
Immunosensor
Metal Nanoparticles
Methods. Procedures. Technologies
Serum Albumin - immunology
Tetramethylbenzidine (TMB)
Various methods and equipments
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Summary:In this report we have used gold nanoparticles (AuNPs) to covalently attach an antibody (Ab 1) using a spacer arm. The AuNPs/Ab 1 modified gold electrode was used for a sandwich electrochemical immunoassay. The detection was done using cyclic voltammetry and impedance measurements using Horse Radish Peroxidase (HRP) as enzyme label on secondary antibody (Ab 2) and 3,3′, 5,5′-tertramethyl benzidine (TMB) as an electroactive dye. The cyclic voltammetric experiments showed three clear peaks at potentials 154 mV, −33 mV and −156 mV. There was an increase in the both anodic and cathodic current values for the peak at potential −33 mV, when H 2O 2 was added and the other peaks observed at potential 154 mV and −156 mV resulted due to the oxidation and reduction of TMB. The detection limit of this electrode was 2 ng/mL or 10 pg/5 μL of the analyte. The electrochemical impedance spectroscopy studies demonstrate that the formation of antigen–antibody complexes increases the series resistance and thus confirms the assembly on the electrode. This study showed that AuNPs was efficient in preserving the activity and orientation of the antibody and it can form a major platform in many clinical immunoassays.
ISSN:0956-5663
1873-4235
DOI:10.1016/j.bios.2010.01.029