Publications (71) View all
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Article: Optimization of a lateral flow immunoassay for the ultrasensitive detection of aflatoxin M1 in milk.
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ABSTRACT: A high sensitive immunoassay-based lateral flow device for semi-quantitatively determine aflatoxin M1 (AFM1) in milk was developed. Investigation and optimization of the competitor design and of the gold-labelling strategy allowed the attainment of the ultra-sensitive assessment of AFM1 contamination at nanograms per litre level (LOD 20ngL(-1), IC50 99ngL(-1)), as requested by European regulations. A one order of magnitude detectability enhancement in comparison to previously reported gold colloid immunochromatographic assays for this toxin was obtained. Direct detection of the target toxin in milk could be obtained by acquiring images of the strips and correlating intensities of the coloured lines with analyte concentrations. The one-step assay can be completed in 17min, including a very simple and rapid sample preparation, which allowed the application of the assay to milk samples which differ in fat and protein contents. Although imprecise (mean RSD about 30%), the method proved to be accurate and sensitive enough to allow the correct attribution of sample as compliant or non-compliant according to EU legislation in force. Agreeing results to those of a reference ELISA were obtained on 40 milk samples by matrix-matched calibration in pasteurized milk.Analytica chimica acta 04/2013; 772:75-80. · 4.31 Impact Factor -
Article: A LATERAL FLOW IMMUNOASSAY FOR THE RAPID DETECTION OF OCHRATOXIN A IN WINE AND GRAPE MUST.
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ABSTRACT: A one-step lateral flow immunoassay was developed for semi-quantitatively detecting ochratoxin A (OTA) in wines and grape musts. Matrix-matched calibration curves carried out in blank wines showed a detection limit of 1 g l-1 and IC50 of 3.2 g l-1. Relative standard deviations for intra- and inter-day precision were in the 20 - 40% range. A simple treatment of samples, which only included dilution with sodium bicarbonate and polyethylene glycol (4% w/v) for red and white wines and the further addition of ethanol (12% v/v) for grape musts, was established. The developed assay allowed OTA detection in 5 minutes and proved to be accurate and sensitive enough to allow the correct attribution of samples as compliant or non-compliant according to EU legislation. Agreeing results to those of a reference chromatographic method were obtained on 38 wines and 16 musts. Although some lateral flow devices aimed at detecting OTA have been previously described, this is the first assay capable to measure the toxin in wine and grape must, which represent a major source of OTA dietary intake. Analytical performances of the method are comparable or better than previously reported assays showed. In addition, the assay, including sample treatments, is extremely simple and rapid, and can be effectively regarded as a one-step assay virtually usable anywhere.Journal of Agricultural and Food Chemistry 11/2012; · 2.82 Impact Factor -
Article: An innovative approach to molecularly imprinted capillaries for polar templates by grafting polymerization.
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ABSTRACT: Molecularly imprinted polymers have been successfully used as selective stationary phases in capillary electrophoresis. Notwithstanding, this technique suffers from several drawbacks as the loss of molecular recognition properties in aqueous media and the lack of feasibility for imprinted systems directed towards highly polar templates soluble in aqueous environments only. Thus, the preparation of imprinted polymers for highly polar, water-soluble analytes, represents a challenge. In this work, we present an innovative approach to overcome these drawbacks. It is based on a surface molecular imprinting technique that uses preformed macromonomers as both functional recognition elements and cross-linking agents. A poly-2-hydroxyethyl-co-methacrylic acid linear polymer was grafted from the surface of silica capillaries. The grafted polymer was exhaustively esterified with methacrylic anhydride to obtain polyethylendimethacrylate-co-methacrylic acid linear chains. Then, as a proof of concept, an adequate amount of a very polar template like penicillin V was added in a hydro-organic mixture, and a thin layer of imprinted polymer was obtained by cross-linking the polymer linear chains. The binding behaviour of the imprinted and non-imprinted capillaries was evaluated in different separation conditions in order to assess the presence of template selectivity and molecular recognition effects. The experimental results clearly show that this innovative kind of imprinted material can be easily obtained in very polar polymerization environments and that it is characterized by enhanced molecular recognition properties in aqueous buffers and good selectivity towards the template and strictly related molecules.Journal of Molecular Recognition 06/2012; 25(6):377-82. · 3.31 Impact Factor -
Article: A rational route to the development of a competitive capillary electrophoresis immunoassay: assessment of the variables affecting the performances of a competitive capillary electrophoresis immunoassay for human serum albumin.
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ABSTRACT: Affinity capillary electrophoresis is a powerful analytical tool to extract quantitative information about the binding properties of different interacting systems. The use of LIF detection makes the technique suitable for screening strong binding interactions. The non-equilibrium electrophoretic separations of pre-equilibrated mixtures of ligand and receptor are generally used for such strong molecular interactions allowing the assessment of capillary electrophoresis immunoassays, mostly in competitive formats. As the analytical performances of the assay strongly depend on the preservation of the binding properties during the separation, a rational route to assay development has to be followed to get the best conditions. The paper describes the steps followed to set-up a competitive immunoassay for human serum albumin (HSA) by using a labeled protein (HSA-FITC) and an anti-HSA polyclonal antiserum. A labeling degree of around 1 of the HSA-FITC conjugates is needed to get narrow electrophoretic peak while the titration curve is used to define the optimal antiserum dilution. An antiserum-labeled protein affinity constant of 1.34×10(7) M(-1) was measures in the selected separation conditions. Furthermore, in order to maximize the assay competition between the labeled and unlabelled HSA a short pre-incubation step of the antiserum with the unlabelled HSA (the analyte) was introduced to promote a sharp increase in assay sensitivity.Talanta 05/2012; 94:65-9. · 3.79 Impact Factor -
Article: Lateral-flow immunoassays for mycotoxins and phycotoxins: a review.
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ABSTRACT: Natural toxin (for example mycotoxin and phycotoxin) contamination of food is of safety and economic concern, so much effort is devoted to the development of screening methods which enable the toxins to be continuously and widely monitored in food and feed. More generally speaking, rapid and non-instrumental assays for detection of a variety of food contaminants are generating ever-increasing scientific and technological interest because they enable high-throughput, economical, on-site monitoring of such contaminants. Among rapid methods for first-level screening of food contaminants, lateral-flow immunoassay (LFIA), also named immunochromatographic assay or immune-gold colloid immunoassay, has recently attracted scientific and industrial interest because of its attractive property of enabling very rapid, one-step, in-situ analysis. This review focuses on new aspects of the development and optimization of lateral-flow devices for mycotoxin and phycotoxin detection, including strategies for management of matrix interference and, particularly, for investigation of the improvements achieved by signal-enhancing strategies or by application of non-gold nanoparticle signal reporters.Analytical and Bioanalytical Chemistry 04/2012; · 3.78 Impact Factor
