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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

Multi-analyte detection of environmentally relevant pesticides is performed by using a two-channelled surface plasmon resonance (SPR) biosensor. The special design of the SPR instrument allows the determination of several analytes (DDT, chlorpyrifos and carbaryl) via different immobilization formats. First, simultaneous pesticide monitoring is possible by flowing chlorpyrifos, carbaryl or DDT samples separately over each channel of the SPR system, wherein their corresponding recognition element was previously immobilized. The second approach is based on the multiple and combined immobilization of several analyte recognition elements on the sensing surface of one individual flow cell. In this format, the analysis time for all three pesticides varied from 40 to 60 min depending on the number of regeneration cycles. In most cases, similar detection limits were attained for the target analyte irrespective of the assay format, with sensitivity values at the nanogram per litre level (18-50 ng L(-1)). The assay reproducibility was proved through the repeated use of the same sensor surface for over more than 200 assay cycles, whereas the absence of biosensor response to non-related analytes showed the specificity and reliability of the analysis. The SPR instrument, including optics, electronics and microfluidics, is already commercialised by the company SENSIA, SL.

ElsevierMarch Iborra, MDC.; García Narbón, JV.; Sánchez, Á.; Arnau Vives, A.; Jiménez Jiménez, Y.; García, P.; Manclus Ciscar, JJ.... (2015). High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors. Biosensors and Bioelectronics. (65)