Development of Analytical Methods Using Immunological Reactions

Analytical methods using antibodies have made remarkable progress in the fields of medicine and life sciences. However, hydrophobic low molecular compounds, such as pesticides and mycotoxins in foods, have not been put into practical use because antibodies, which are proteins, are easily influenced by organic solvents using their extractions. In the authors team, antibodies for their compounds were prepared, and analytical methods were attempted to develop using them. As results, various monoclonal antibodies tolerated to organic solvents were prepared, and ELISAs for residue analyses of pesticides in garden crops and immunoaffinity columns for cleaning up mycotoxins in foods were developed. Next, surface plasmon resonance immunosensors were introduced to establish a simultaneous analysis method for several pesticides. One of the immunosensors was also applied to detect O antigen on Escherichia coli, but it was difficult to remove bacteria after signal detection because the O antigen binds to the antibody at multiple points. It was successfully removed by a physical method using a gel such as gelatin or agarose as the results of trial and error search. The sensor regeneration maintained the antibody function. This method could be applied to detection of animal cells as well as bacteria.