Integrated optical sensors have become important in recent years since they are the only technology which allows the direct detection of biomolecular interactions. Moreover, silicon microelectronics technology allows mass production as well as the fabrication of nano-/macrosystems on the same platform by hybrid integration of sources, sensors, photodetectors and complementary metal-oxide semiconductor electronics.For the fabrication of an optical sensor nanodevice with an integrated Mach–Zehnder interferometric (MZI) configuration, the optical waveguides must have two main features: monomode behaviour and a high surface sensitivity. In this paper we present the development of a MZI sensor based on total internal reflection waveguides with nanometre dimensions. The aim is to use these sensors in environmental control to detect water pollutants by immunoassay techniques.

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The present work describes the production and characterization of monoclonal antibodies (MAbs) to the insecticide chlorpyrifos and their incorporation into several ELISA configurations. With this aim, a collection of chlorpyrifos haptens was synthesized by introducing appropriate spacers in opposite sites of the analyte molecular structure. From mice immunized with protein conjugates of these haptens, several hybridomas secreting MAbs with the ability to sensitively bind the analyte were obtained. MAbs showing the highest affinity to chlorpyrifos in homologous assays (I 50 values in the 20−220 nM range) were selected. Hapten heterology involving modifications of the moiety closer to the attachment site provided the highest improvement in sensitivity. MAbs displayed striking differences in their cross-reactivity pattern with structurally related compounds. One MAb (I 50 around 10 nM) was incorporated into other ELISA formats. No remarkable changes of assay characteristics, other than immunoreagent consumption and immunoassay procedure, were found. These ELISAs are potentially very valuable analytical tools for the rapid and sensitive determination of this insecticide. Keywords: Insecticide; chlorpyrifos; hapten design; monoclonal antibodies; ELISA; analysis