Analytical Sciences

A Glyco-chip for the Detection of Ricin by an Automated Chemiluminescence Read-out System

Maria HUEBNER, Klaus WUTZ, Agathe SZKOLA, Reinhard NIESSNER, and Michael SEIDEL

Chair of Analytical Chemistry and Institute of Hydrochemistry, Technical University of Munich, Marchioninistr. 17, Munich, Germany

The plant toxin ricin is a lectin that binds to D-galactose or lactose moieties by multivalent interactions. In the present work, this avidity was used to develop a novel sandwich glyco-immunoassay using a carbohydrate microarray. For realization, 6-azidohexyl-lactose was immobilized on an alkyne silane surface by Cu(I) catalyzed click chemistry. This procedure is fast, and prevents any nonspecific binding on the microarray surface. Ricin binds via its B-chain to the lactose moieties, and is detected by the biotinylated anti-ricin A-chain. By adding a horseradish peroxidase-labeled streptavidin, a chemiluminescence signal can be generated. This method is described as a sandwich-type glyco-immunoassay. The signal on the glyco-chip can be regenerated for at least 10 measurements. The limit of detection was estimated to be 80 ng mL⁻¹. The assay was carried out on the automated microarray readout platform MCR 3. In this way, it took 20 min for one measurement, including regeneration of the chip surface.

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