High-affinity anti-abrin-a monoclonal and polyclonal antibodies were used to develop a sandwich immunochromatographic assay and silver enhancement technology was used to further increase the sensitivity. Using a matrix of double distilled water or soybean milk with added abrin-a, the visual detection limit was found to be 10 ng mL(-1). The detection limit was 0.1 ng mL(-1) for abrin-a, an increase in sensitivity of 100-fold when the silver enhancement technology was employed. The assay was portable and very simple to perform and the detection was completed within 20 min without complicated handling procedures. There was no significant cross-reactivity with several homologous toxins and associated agglutinin. The assay reagents could be stored for 12 weeks at 4°C without significant loss of activity. These characteristics make the strip assay to be an ideal candidate for the development of a rapid toxin detection kit.
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