A strip liposome immunoassay for aflatoxin B1

A technique has been developed for the preparation of aflatoxin B-1 (AFB(1))-tagged liposomes encapsulating a visible dye. These liposomes have several useful potential analytical applications, one of which is demonstrated. A simple plastic-backed nitrocellulose strip is the basis for an assay for detecting AFB(1). Samples containing aflatoxin B-1 are allowed to migrate by capillary action along the strip into a zone containing immobilized antibodies; then aflatoxin B-1-tagged, dye-containing liposomes are allowed to migrate into the same area, filling any remaining antibody sites. The liposomes that bound to the antibody zone exhibit an intense purplish pink color whose optical density is inversely proportional to the aflatoxin concentration in the sample. The device is capable of detecting aflatoxin B-1 at levels down to 20 ng and could serve as a rapid procedure for visual screening of agricultural and food samples for AFB(1) or, with densitometry, as an inexpensive quantitative assay.