Immunosensors for Pesticide Analysis in Food and the Environment, and Enzymatic Biosensors for Sweat Ions Control during Sport Practice

Abstract

Over the past two decades, a wide collection of monoclonal antibodies to pesticides and other low-molecular weight contaminants has been produced at the “Grupo de Inmunotecnología” of the “Instituto de Bioingeniería” (I³BH) at the “Universidad Politécnica de Valencia” (UPV, España). Using these monoclonal antibodies and suitable assay conjugates as specific immunoreagents, immunosensors were developed for the analysis of pesticide residues in environmental and agri-food matrices. Surface Plasmon Resonance (SPR) and Piezoelectric Quartz Crystal Microbalance (QCM) were used as transduction principles. Both types of immunosensors were based on competitive immunoassays in the conjugate-coated format.

SPR immunosensors were developed for contaminants belonging to different chemical families: N-methylcarbamate (Carbaryl), organophosphorus (Chlorpyrifos) and organochlorinated (DDT) insecticides, the metabolite 3,5,6-trichloro-2- pyridinol (TCP), the fungicide Thiabendazole (TBZ) and the plasticizer compound Bisphenol A (BPA). Most of the SPR immunosensors achieved an extremely high sensitivity, which allowed their application to the direct analysis of vegetable or packed food samples, and even water samples, at European regulatory levels.

Piezoelectric QCM immunosensors for carbaryl, TCP and BPA were also developed. Despite being less sensitive than SPR immunosensors, QCM immunosensores also allowed the precise and accurate determination of the target compounds in fruit juices at European regulatory levels.

Enzymatic biosensors for the determination of the alkaline Na⁺ and K⁺ ions in sweat were also developed, with the aim of providing a new tool to prevent heat stroke during intensive sport or physical activity. Sweat concentrations of the ions were were determined by enzymatic reactions where they act as activators. The products of the enzymatic reactions were optically detected by visible (Na⁺) and UV (K⁺) absorbance measurement, using a miniaturized portable device with appropriate LEDs as light sources and photodiodes as sensor elements. A sweat Na⁺ concentration over 150 mM (3500 mg/l) could be considered as an alarm level of excessive effort.