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•A novel alternariol hapten was designed for heterologous immunoassay development.•Two quick immunoassays were optimized for alternariol analysis in fruit juices.•The direct cELISA ...could determine alternariol at trace levels in 25 min.•The lateral-flow assay allowed alternariol detection at 4 ng/mL in 15 min.
Alternariol is an emerging mycotoxin that may be present in many foods at relatively high concentrations. Therefore, sensitive analytical methods are needed to reduce human exposure to this secondary fungal metabolite. The aim of the present study was to develop alternative immunochemical methods for the rapid analysis of alternariol using novel homemade monoclonal antibodies. In this study, a direct competitive enzyme-linked immunosorbent assay for alternariol is reported for the first time, with an IC50 value and a detection limit of 0.020 ng/mL and 0.004 ng/mL, respectively. Under the optimized immunoassay conditions, alternariol could be accurately and precisely quantified in fruit juice samples in only 25 min. In addition, a nanoparticle-based lateral-flow immunochromatography assay with an IC50 value and a visual detection limit of 0.24 ng/mL and 1 ng/mL, respectively, was developed. This immunoassay was validated according to European guidelines for portable semiquantitative analytical methods. Thus, juice samples with alternariol levels above 4 ng/mL were detected by this rapid method in only 15 min, with a negligible false suspect rate.
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•MoTe2/MoSe2 flake composite films obtained by a hybrid process.•MoOy (2 < y < 3) nucleated first on Si (100) by sol–gel processing.•MoTe2/MoSe2 composite films achieved by H2 ...reduction and isothermal closed space vapor transport of the chalcogenides.•Multilayered nanocomposite MoTe2(1-x)Se2x/MoSe2 alloy films grown at 600 °C.•Out-of-plane flake-like structure confirmed by microscopy and spectroscopy.
This study describes the sol–gel processing of MoOy on Si (100) to subsequently achieve out-of-plane MoTe2/MoSe2 flake composite films by an isothermal closed space vapor transformation. The oxide precursor films have been prepared from a Mo isopropoxide solution in isopropanol and acid catalysis induced by HCl. Thermal annealing at 200, 400 and 600 °C enhanced the condensation after xerogel formation. An x-ray absorption analysis demonstrates that films condensed at 200 °C are at an intermediate chemical state between MoO3 and MoO2. To achieve MoTe2/MoSe2 composite films, the precursor oxide films were reduced in H2 and exposed to the chalcogenides by isothermal closed space vapor transport at 600 °C. The multilayered nanocomposite films grow with an out-of-plane flake-like structure and an evident integration of Se in the MoTe2 phase according to a MoTe2(1-x)Se2x alloy, with an estimation of x of 0.25. The alloy and the orientation of the flakes are consistent with the bands present in the Raman spectrum. These films are attractive for applications requiring high surface area interfaces favoring gas or ion exchange reactions with transition metal dichalcogenides.
Spirotetramata tetramic acid insecticideis rapidly metabolized or degraded to give spirotetramat-enol; so, common residue definitions include the sum of both compounds. In the present study, two ...spirotetramat-functionalized derivatives (haptens) have been designed to generate immunoreagents to these molecules for rapid immunochemical analysis. Haptens have been synthesized with alternative linker tethering sites and, for the first time, high-affinity antibodies have been generated with different specificities to these active principles. Two sensitive assays have been developed using the same antibody in different formats, and by using linker-site heterologous haptens, the selectivity of the final immunoassay could be improved. A generic immunoassay with sensitivity similar to spirotetramat and spirotetramat-enol and a specific assay of spirotetramat-enol have been developed. The described antibody and bioconjugates showed great potential for sensitive immunosensor development and analysis of this complex analyte.
El control efectivo de la calidad y seguridad de los alimentos requiere de métodos analíticos que garanticen la determinación fiable de cualquier sustancia potencialmente perjudicial para el ...consumidor que pueda estar presente en el alimento antes de su distribución y comercialización. Una de las aproximaciones analíticas que contribuye a garantizar este objetivo engloba una serie de técnicas que tienen en común la utilización de anticuerpos como elementos esenciales para la detección del analito diana, y que en conjunto reciben el nombre de métodos inmunoquímicos. Este artículo pretender aportar una visión básica de los principios bioquímicos subyacentes a estas tecnologías y cuáles son sus ventajas y limitaciones en la determinación de contaminantes químicos, residuos y aditivos en matrices alimentarias. En la última parte se comentan algunas de nuestras iniciativas en este ámbito que han dado lugar a kits rápidos disponibles comercialmente tras haber transferido la tecnología correspondiente al sector industrial.
In 2013, quinoxyfen was included in the list of priority hazard pollutants of the European Water Framework Directive due to its toxicity to aquatic organisms. However, few analytical methods for the ...analysis of this fungicide have been reported and no rapid immunochemical methods have been published so far. In the present study, immunoreagents for quinoxyfen analysis were generated for the first time and an enzyme-linked immunosorbent assay was developed. Two carboxylated derivatives of quinoxyfen were designed on the basis of the minimum energy conformation of the target compound. Active esters of those novel compounds were prepared using N,N′-disuccinimidyl carbonate, and purified for covalent coupling to proteins. Matrix-assisted laser desorption mass spectrometry of the prepared bioconjugates showed optimum hapten-to-protein molar ratios. Moreover, high-affinity antibodies specific of quinoxyfen were raised. As proof of concept, an immunoassay was evaluated using a heterologous conjugate, which afforded sensitivity values in the low nanomolar range. Moreover, excellent recoveries and coefficients of variation were obtained from the analysis of environmental water samples fortified with quinoxyfen. A limit of quantification of 60 μg/L was determined. The prepared bioconjugates and antibodies could be valuable immunoreagents for the development of a variety of rapid immunosensors for quinoxyfen determination in environmental samples.
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•Quinoxyfen is a priority hazard pollutant in the European Water Framework Directive.•Functionalized derivatives were synthesized for covalent conjugation to proteins.•Bioconjugates and high-affinity antibodies specific of quinoxyfen were prepared.•A sensitive immunoassay (LOQ = 60 μg/L) was optimized and developed.•Precision and accuracy of the method were verified with environmental water samples.
•In-house developed immunoassays have been employed for multiresidue analysis of fungicides in wine.•Evidence of widespread contamination of commercial wines by fungicides was observed.•Results show ...a relationship between fungicide occurrence and geographical origin.•Wineries should adopt measures aimed at reducing fungicide residues in wines.•Setting up of specific maximum residue limits for pesticides in wines is suggested.
Azoxystrobin, boscalid, cyprodinil, fenhexamid, and pyrimethanil are new generation fungicides extensively employed in order to combat diseases affecting vineyards worldwide. Owing to their physico-chemical characteristics, residues of these compounds on grapes are transferred to must and wine. In this study, a survey of the occurrence of these fungicides in international wines was carried out by using rapid antibody-based assays. Results are discussed as a function of wine type and sample geographical origin. 44.4% of the samples contained at least one of the targets (>10μgL−1). Fungicide residue occurrences were 22.4%, 19.2%, 18.8%, 6.8%, and 1.2% for pyrimethanil, boscalid, fenhexamid, cyprodinil, and azoxystrobin, respectively, while residue contents higher than 100μgL−1 were found in 8.4% of the samples. This study shows that contamination of commercial wines with pesticides is an issue of worldwide relevance with potential implications for consumer health and international trade.
Early warning systems for monitoring toxic events may benefit from the availability of monoclonal antibodies enabling the sensitive and specific detection of anatoxin‐a, a cyanotoxin involved in ...numerous cases of animal poisoning resulting from toxic algal blooms in freshwaters. Through the synthesis of three functionalized derivatives of anatoxin‐a, we have succeeded in generating the first‐ever reported immunoreagents (bioconjugates and antibodies) suitable for the development of immunoanalytical approaches aimed at rapid and onsite detection of this harmful cyanotoxin.
Three functionalized derivatives, or haptens, of anatoxin‐a were synthesized. One of these derivatives allowed the production of the first‐ever reported immunoreagents (bioconjugates and antibodies) suitable for the point‐of‐care detection of this harmful cyanotoxin.
Nowadays, instrumental methodologies and rapid bioanalytical techniques complement each other for the analysis of toxic chemical compounds. Fluxapyroxad was commercialized a few years ago as a ...fungicide and today it is being used worldwide to control a variety of pests. In the present study, the development of monoclonal antibody-based immunochemical methods for the analysis of this chemical in food samples was evaluated for the first time. Novel haptens were synthesized and protein bioconjugates were prepared. High-affinity and specific monoclonal antibodies to fluxapyroxad were generated from two haptens with alternative linker tethering sites. Haptens with linker site heterology and a structurally heterologous hapten with a minor modification of the molecule conformation and volume but with a significant alteration of the electronic density of the pyrazole moiety were evaluated for immunoassay development. Direct and indirect competitive immunoassays were characterized and optimized, showing IC50 values for fluxapyroxad of 0.14 and 0.05 ng mL-1, respectively. The combination of two heterologies was particularly adequate in the indirect format. The two developed immunoassays showed excellent recoveries and coefficients of variation in fluxapyroxad-fortified plums and four varieties of grapes. Finally, a good correlation was found between the indirect immunoassay and UPLC-MS/MS when fruit samples with incurred residues of fluxapyroxad were analyzed. These monoclonal antibody-based immunochemical methods hold great promise for fluxapyroxad monitoring.
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