To protect human health and assure a safe food supply, monitoring food for contaminants is essential. In particular, mycotoxins are widely found and associated with known toxic effects. Changes in agricultural practices and implementation of global food monitoring regulations have resulted in decreased contamination. Nevertheless, mycotoxins and especially aflatoxin, continue to be a significant problem. A number of commercially available immunoassays are widely used for monitoring because they are accurate, easy to use, rapid and low cost. We have been exploring the use of single domain heavy chain antibodies (VHH) as an alternative to the classic polyclonal or monoclonal antibodies used in commercial kits. These are a unique antibody found in camelids and sharks. The binding domain is smaller and less complex than in conventional antibodies making it more amenable to cloning techniques. The engineered antibodies, known as VHHs, have affinities to their antigens that are similar to the corresponding IgG. The VHHs have additional advantages such as thermal stability, stability toward chaotropic agents, improved water solubility and ease of genetic manipulation. These characteristics have made VHH a viable agent in clinical diagnostics and therapeutics. However, there have been few reports of the development of VHH for small molecules, in particular food contaminants. We have developed alpaca-derived VHH for mycotoxins, pesticides and flame retardants. Stringent panning strategies have led to selection of VHH that had similar sensitivity and cross reactivity patterns to the existing polyclonal and monoclonal antibody assays. The versatility of the VHH has been demonstrated by their use in classical ELISA as well as in a microfluidic biosensor driven by a smart phone and an impedance biosensor. We also demonstrated the ease of genetic manipulation by fusing the VHH to an enzyme resulting in a faster, simpler, one-step assay. Recombinant VHHs have proven to be an excellent alternative to existing antibody technology and should prove valuable for the next generation of mycotoxin immunoassay.

Application of nanobodies, sensors and other immunochemical techniques for the analysis of mycotoxins and other small molecules

251st National Meeting (2016)

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