Functionalized surfaces for optical biosensors: Applications to in vitro pesticide residual analysis

Functionalized biosensing surfaces were developed for chemiluminescent immu noassay of pesticides. Two approaches to construct functionalized surfaces were tested: (i) pesticide is immobilized to the surface and interacts with a labeled antibody; (ii) antibody is immobilized and interacts with a labe led pesticide. As labels alkaline phosphatase and peroxidase were used with their corresponding substrates CSPD and luminol, respectively. Light produ ced by chemiluminescent substrate was detected by a thermoelectrically cool ed CCD camera or a photomultiplier. The best detection limit 0.00001 ng/ml was obtained using antibodies immobilized to dextran-enhanced surface. Comp letely renewable surface was obtained using reversible lectin-monosaccharid e interaction, one surface was used for 200 analyses without any loss of bi nding capacity. Most favorable stability and cost per analysis was achieved with molecularly imprinted polymer (MIP) instead of antibody. The function alized biosensing surfaces were prepared to detect 2,4-dichlorophenoxyaceti c (2,4-D) acid as a model pesticide. The developed concepts are, however, g enerally applicable to other pesticides and to other optical formats, e.g. optical fiber. (C) 2001 Kluwer Academic Publishers.