Session: Advances in Electrochemistry:

Domoic acid is a heterocyclic amino acid neurotoxin and the principal toxin associated with amnesic shellfish poisoning (ASP) produced by certain species of marine algae. It can accumulate in high concentrations in the shellfish tissues when the toxic phytoplankton is present in the surrounding waters. Ingestion of domoic acid contaminated shellfish leads to ASP, which is characterized by both gastrointestinal and neurological symptoms, including severe headache, seizures, tremors, and either temporary or permanent memory loss.

The detection of domoic acid is done through an enzymatic immunoassay that uses magnetic beads to support the immunoreaction and screen-printed electrodes as suitable detectors of the enzymatic product.

The immunological reaction is performed in solution, in which the domoic acid, antigen, and domoic acid labeled with horseradish peroxidase are incubated with the rabbit IgG domoic acid antibody. Subsequently, the antibody-antigen complex is captured by the anti-rabbit IgG modified magnetic beads. Then, the magnetic beads are deposited onto the electrode surface with the help of a magnet placed under the screen printed electrode. Finally, the analytical signal is obtained by amperometric detection of the product enzymatically generated from the mixture of H₂O₂and 3,3,5,5-tetramethylbenzidine (TMB).

The use of magnetic beads provides the capability to preconcentrate the sample and avoid poisoning of the electrode surface through nonspecific absorptions.

The experimental conditions of the magneto-immunological assay have been optimized and a calibration curve has been obtained between 0-2 ng/mL domoic acid, with the ability to detect down to 100 pg/mL.

Daniel Izquierdo-Bote

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