An impedimetric immunosensor for the detection of autoantibodies directed against gliadins.
An immunosensor has been developed for the detection of autoantibodies directed against wheat gliadin, a protein fraction of cereal gluten which is involved in celiac disease. The immunosensor is based on the immobilization of gliadins onto gold electrodes covered with a polyelectrolyte layer of poly(4-styrenesulfonic acid sodium salt). The immobilization was monitored by quartz crystal microbalance (QCM) analysis. The antigen-antibody interaction signal was amplified by an incubation step with peroxidase-labeled immunoglobulins and subsequent peroxidase-catalyzed oxidation of 3-amino-9-ethylcarbazole (AEC). Changes in the insulating properties of the electrode layer were measured by electrochemical impedance spectroscopy (EIS) in the presence of ferri/ferro-cyanide. Impedance spectra could be fitted to a Randles equivalent circuit with high accuracy. Exposing the sensor electrodes to various antigliadin antibody concentrations resulted in proportional changes in the charge transfer resistance. A calibration graph for the detection of antigliadin antibodies was established for antibody concentrations between 10(-8) and 10(-6) M. Finally, the sensor was used for the determination of antigliadin autoantibodies of the IgG and IgA type in several human sera.
Balkenhohl
T
T
University of Applied Sciences Wildau, Biosystems Technology, Bahnhofstr. 1, 15745 Wildau, Germany.
Lisdat
F
F
D001323:Autoantibodies / Q000032:analysis*; D002446:Celiac Disease / Q000276:immunology; D017097:Electric Impedance; D005903:Gliadin / Q000276:immunology*; D006046:Gold; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D013057:Spectrum Analysis
D001323:Autoantibodies; D006046:Gold; D005903:Gliadin