Amperometric immunosensor for nonylphenol determination based on peroxidase indicating reaction.
ABSTRACT Novel immunosensor for nonylphenol (NP) determination has been developed by immobilization of specific antibodies together with horseradish peroxidase on the surface of carbon screen-printed electrode. The signal of the immunosensor is generated by the involvement of NP accumulated in the peroxidase oxidation of mediator (Methylene Blue, hydroquinone or iodide). This results in the increase of the signal recorded by linear-sweep voltammetry. The sensitivity of the detection depends on the nature of mediator, its concentration and incubation period. Cross-selectivity of the response toward readily oxidized phenolic compounds has been determined. The immunosensor developed makes it possible to detect from 20 microgL(-1) to 44 mgL(-1) of NP with detection limit 10 microgL(-1) of NP.
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ABSTRACT: The development of express method for detection of endocrine-disrupting chemicals (EDC) such as alkylphenols is required for ecological monitoring. Several attempts have been made to produce antibodies against 4-nonylphenol (NP) in recent years. This work describes the production of new antibodies against NP and also summarizes the characterization of antibodies obtained earlier. Three approaches used to produce alkylphenol-specific antibodies are compared; these are based on: 1. omega-(4-hydroxyphenyl)nonanoic or omega-(4-hydroxyphenyl)heptanoic acid NP derivatives designed to mimic the linear NP isomer; 2. 4-aminophenol, which potentially mimics various substituted phenolic compounds with different side-chain structures at position 4 of the benzene ring; and 3. a mixture of branched NP isomers, conjugated to the carrier protein via a benzene ring by the Mannich reaction, and expected to be the closest mimic of NP structure by preserving its natural alkyl moiety.Fluorescence polarization immunoassays based on different combinations of antibody and labeled antigen for screening detection of NP were developed and structural aspects of assay sensitivity and specificity were investigated. The assays based on the antisera raised against omega-(4-hydroxyphenyl)nonanoic acid and NP conjugate via Mannich reaction are capable of express detection of NP with detection limit of 7 microg mL(-1 )and assay dynamic range of 18-300 microg mL(-1).Analytical and Bioanalytical Chemistry 03/2004; 378(3):634-41. · 3.66 Impact Factor
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ABSTRACT: A range of monoclonal antibody-based competitive immunoassays in the format of microtitre plate ELISA and dipstick tests for quantitative and semi-quantitative detection of 4- n -nonylphenol in water was developed. A simple visual dipstick test was based on changing of spot colour from green to brown in the presence of 4- n -nonylphenol at concentrations within the range 10-100 ng mL(-1). Two different detection systems were used for quantitative immunoassay. Application of enhanced chemiluminescence (ECL) resulted in an increase of the sensitivity of ELISA when compared to conventional colorimetric detection. Thus a detection limit of 0.06 ng mL(-1 )of 4- n -nonylphenol was achieved with IC(50) 2.0 ng mL(-1). The tests developed were applied to natural and spiked water samples.Analytical and Bioanalytical Chemistry 05/2003; 375(8):1017-9. · 3.66 Impact Factor
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ABSTRACT: It has been hypothesized that recent adverse trends in humans are linked to an increased exposure to potential endocrine disrupting agents. These include widely used compounds that mimic the action of sex hormones, including bisphenol A, phthalates and parabens. Since the chemical structure is not sufficient to determine whether a chemical will act as an oestrogen, there is a need for assays that can determine whether a compound interferes with the endocrine systems. The Environmental Protection Agency has recently suggested a testing scheme, composed of an initial screening followed by a more comprehensive investigation of chemicals that are positive in the screening. The screening will use several short-term assays to screen many thousands of compounds for potential endocrine disrupting properties. However, none of these tests determines compound-induced effects on the expression of endogenous genes, which is the cause of the adverse effects. We propose to use a precise quantification of the expression levels of endogenous oestrogen-regulated genes to test whether a chemical has oestrogenic properties, and describe how an endogenous gene expression assay can be established and conducted. Furthermore, different applications of such an assay are discussed: in cell cultures; in experimental animals; or, optimally, directly in blood samples from exposed humans.Andrologia 10/2000; 32(4-5):271-8. · 1.75 Impact Factor