Immunochemical methods for mycotoxin analysis: from radioimmunoassay to biosensors

Abstract

Immunochemical methods have been used in diagnosis of diseases both for humans and animals for many years. However, wide application of these methods for analytical purpose was not initiated until the nineteen fifties when Yalow developed a radioimmunoassy for insulin1). In addition to the specific antibody, the modern immunochemical methods use a sensitive marker for the analyte and a good method to separate the bound and free analyte in the specific antigen (Ag) and antibody (Ab) interaction. The assay systems became a new highly sensitive, specific and simplified versatile tool for the analysis of many biologically active substances, including low molecular contaminants such as mycotoxin. In the last four decades, new approaches to make sensitive markers have been made. For example, by conjugating the enzymes to the Ag or Ab to amplify the signal, more sensitive and versatile enzyme-immunoassay systems have been developed. With the availability of sensitive instruments, more fluorescence-tagged markers are now being used. Simplified and effective methods for the separation of free and bound species are now available. In addition to using animals for Ab production, monoclonal Ab technology was introduced. Such developments have led to a wide application of immunoassays for the analysis of contaminants in foods and agricultural products. Recent development of novel separation techniques and sensitive detection systems have led to the development of several immunochemical based biosensors. Thus, a new dimension of immunoassay system is now emerged. Whereas many types of immunoassays are now available for mycotoxins, most approaches are based on the competition of binding between unlabeled toxin in the sample and labeled toxin in the assay system for the specific binding sites of Ab molecules. Because of limited space, this review will focus only on important developments and applications of immunoassays for mycotoxins. For details, the readers should consult the original papers and recent reviews both on the overall analytical methods2-9) and immunoassays for mycotoxins10-18).