Use of gold nanoparticle-labeled secondary antibodies to improve the sensitivity of an immunochromatographic assay for aflatoxin B1

We describe a sensitive method for the immunochromatographic determination of aflatoxin B1. It is based on the following steps: 1) Competitive interaction between non-labeled specific primary antibodies and target antigens in a sample and in the test zone of a membrane; 2) detection of the immune complexes on the membrane by using a secondary antibodies labeled with gold nanoparticles. The method enables precise adjustment of the required quantities of specific antibodies and the colloidal (gold) marker. It was applied in a lateral flow format to the detection of aflatoxin B1 and exhibits a limit of detection (LOD) of 160 pg · mL if detected visually, and of 30 pg · mL via instrumental detection. This is significantly lower than the LOD of 2 ng · mL achieved by conventional lateral flow analysis using the same reagents. [Figure not available: see fulltext.].