Publications (2)0 Total impact
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Article: Electrochemical immunosensors for determination of the pesticides 2,4-dichlorophenoxyacetic and 2,4,5-tricholorophenoxyacetic acids
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ABSTRACT: Two immunochemical sensors are described for detection of the pesticides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The assay monitors the competitive binding of free pesticide and pesticide-peroxidase conjugate with antibodies immobilized on a graphite electrode, by measurement of peroxidase activity in the immune complexes on the electrode surface. 5-aminosalicyclic acid and H2O2 are used as substrates. An automated potentiometric device measures changes in redox potential during the peroxidase reaction. The assay parameters were optimized to achieve detection limits of 40 ng/ml 2,4-D and 50 ng/ml 2,4,5-T (in both water and serum). The total time required to perform the assay (including electrode regeneration) was 12 min, compared to about 2 h for solid-phase enzyme immunoassays. The electrode life extends to 60 sequential measurements. The sensors therefore appear suitable for medical and ecological applications.Biosensors and Bioelectronics. -
Article: Immunosensor for the determination of the herbicide simazine based on an ion-selective field-effect transistor
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ABSTRACT: An immunosensor based on the ion-selective field effect transistor (ISFET) was developed for the express determination of herbicide simazine. Polyclonal antibodies against simazine were attached to the ISFET gate via staphylococcal protein A. Two methods of simazine detection were used — (i) competitive immune assay when native (detected) and peroxidase-labelled simazine molecules competed for binding with antibodies on the ISFET surface, and (ii) sequential saturation of antibodies, left unbound after their exposure to native simazine in investigated sample, with labelled simazine. The catalytic activity of bound peroxidase was measured in the presence of ascorbic acid and H2O2. The limit of simazine detection by competitive immune assay was 1.25 ng ml−1, the linearity was observed in the range of 5–175 ng ml−1. Sequential saturation of the antibodies led to the growth of the assay sensitivity up to 0.65 ng ml−1. Acidic treatment of the ISFETs allowed using them several times without loss of the signal amplitude. The analysis had rapid kinetics, its overall time including duration of all preparation stages was around 50 min.Analytica Chimica Acta.
