Delayed Addition of Template Molecules Enhances the Binding Properties of Diclofenac-Imprinted Polymers.

It has been reported that in the molecular imprinting technique, the use of preformed oligomers instead of functional monomers increases the stability of the non-covalent interactions with the template molecule, providing a sharp gain in terms of binding properties for the resulting imprinted polymer. Based on this theory, we assumed that the delayed addition of template molecules to a polymerization mixture enhances the binding properties of the resulting polymer. To verify this hypothesis, we imprinted several mixtures of 4-vinylpyridine/ethylene dimethacrylate (1:6 mol/mol) in acetonitrile by adding diclofenac progressively later from the beginning of the polymerization process.

Direct vs Mediated Coupling of Antibodies to Gold Nanoparticles: The Case of Salivary Cortisol Detection by Lateral Flow Immunoassay.

Stable and efficient conjugates between antibodies and gold nanoparticles (GNP-Ab) are sought to develop highly sensitive and robust biosensors with applications in medicine, toxicology, food safety controls, and targeted drug delivery. Several strategies have been proposed for directing the antibody attachment to GNPs thus preserving antibody activity, including covalently coupling the antibody to a polymer grafted on GNP surface and exploiting the high affinity of bioreceptors as mediators for the binding. Both approaches also allow for shielding GNPs with a protective layer that guarantees the robustness of the conjugate.

Multiplex Lateral Flow Immunoassay: An Overview of Strategies towards High-throughput Point-of-Need Testing.

Simultaneous measurement of different substances from a single sample is an emerging issue for achieving efficient and high-throughput detection in several fields of application. Although immunoanalytical techniques have well-established and prevailing advantages over alternative screening analytical platforms, one of the incoming challenges for immunoassay is exact multiplexing. Lateral flow immunoassay (LFIA) is a leading immunoanalytical technique for onsite analysis, thanks to its simplicity, rapidity, and cost-effectiveness.

Silver and gold nanoparticles as multi-chromatic lateral flow assay probes for the detection of food allergens.

In this study, we report the simultaneous use of gold and silver nanoparticles to set a multicolor multiplex lateral flow immunoassay (xLFIA). Silver nanoparticles (AgNPs), spherical in shape and characterized by a brilliant yellow color, were obtained by a new viable one-step synthetic protocol. AgNPs were stable over time and acceptably robust to conditions used for fabricating LFIA devices.

Colour-encoded lateral flow immunoassay for the simultaneous detection of aflatoxin B1 and type-B fumonisins in a single Test line.

A multiplex Lateral Flow Immunoassay was developed based on the use of a single Test line and multicolour gold nanoparticles (GNPs) as signal reporters. Red and blue GNPs were linked to antibodies directed towards two different analytes and included in a typical lateral flow immunoassay configuration, in which the Test line was formed by the mixture of two antigens. As a result of the immunoreactions occurring at the Test zone, diverse combinations of red and blue GNPs labels were captured.

A versatile and sensitive lateral flow immunoassay for the rapid diagnosis of visceral leishmaniasis.

Visceral leishmaniasis (VL) is a zoonotic infectious disease with a severe impact on humans and animals. Infection is transmitted by phlebotomine sand flies, and several domestic and wild mammals act as reservoirs for the infection, so the prompt detection of infected hosts is crucial to preventing and controlling the spread of the disease and its transmission to humans. A rapid and portable tool for VL diagnosis based on the lateral flow immunoassay (LFIA) technology is described herein.

Evidence of an Important Role of Photochemistry in the Attenuation of the Secondary Contaminant 3,4-Dichloroaniline in Paddy Water.

The secondary pollutant 3,4-dichloroaniline (DCA) is produced by the biological degradation of several herbicides, including propanil in paddy fields. The enzymatic hydrolysis of propanil yields DCA with almost quantitative yield. DCA undergoes rather fast photodegradation in paddy water, mostly by direct photolysis.

A lateral flow immunoassay for straightforward determination of fumonisin mycotoxins based on the quenching of the fluorescence of CdSe/ZnS quantum dots by gold and silver nanoparticles.

A lateral flow immunoassay (LFIA) was developed for the determination of fumonisin mycotoxins. The fluorescence of CdSe/ZnS quantum dots (QDs), observed at excitation/emission wavelengths of 365/525 nm, is suppressed by the addition of silver nanoparticles (SNPs) or gold nanoparticles (GNPs) because SNPs overlap the excitation bands of the QDs, and GNPs overlap the emission bands. The fluorescence of the QDs is recovered upon addition of fumonisins, allowing for the sensitive detection in "positive mode" of the target mycotoxin by monitoring the changes of the QDs fluorescence intensity.

Affinity Capillary Electrochromatography of Molecularly Imprinted Thin Layers Grafted onto Silica Capillaries Using a Surface-Bound Azo-Initiator and Living Polymerization.

Molecularly imprinted thin layers were prepared in silica capillaries by using two different surface polymerization strategies, the first using 4,4'-azobis(4-cyanovaleric acid) as a surface-coupled radical initiator, and the second, S-carboxypropyl-S'-benzyltrithiocarbonate as a reversible addition-fragmentation chain transfer (RAFT) agent in combination with 2,2'-azobisisobutyronitrile as a free radical initiator. The ability to generate imprinted thin layers was tested on two different polymerization systems: (i) a 4-vinylpyridine/ethylene dimethacrylate (4VP-EDMA) in methanol-water solution with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a template; and (ii) methacrylic acid/ethylene dimethacrylate (MAA-EDMA) in a chloroform solution with warfarin as the template molecule. The binding properties of the imprinted capillaries were studied and compared with those of the corresponding non-imprinted polymer coated capillaries by injecting the template molecule and by measuring its migration times relative to a neutral and non-retained marker.

Screening of a Combinatorial Library of Organic Polymers for the Solid-Phase Extraction of Patulin from Apple Juice.

Patulin is a water-soluble mycotoxin produced by several species of fungi. Governmental bodies have placed it under scrutiny for its potential negative health effects, and maximum residue limits are fixed in specific food matrices to protect consumers' health. Confirmatory analysis of patulin in complex food matrices can be a difficult task, and sample clean-up treatments are frequently necessary before instrumental analyses.

Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling.

A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis.

Mycotoxin detection.

Mycotoxins are toxic metabolites of certain fungi that growth on a variety of crops, pre-harvest, during and post-harvest. Because of their toxicity, maximum admissible levels of mycotoxins are regulated worldwide and monitoring of their occurrence in several commodities is mandatory for assuring food safety and consumers' health protection. Analytical methods for mycotoxins include immunochemical-based techniques that principally apply for routinely controls and rapid, on-site detection, and chromatographic-based techniques that provide sensitive, accurate and selective determination of known mycotoxins, besides identification of new or modified compounds through tandem mass spectrometric detectors.

Man-Made Synthetic Receptors for Capture and Analysis of Ochratoxin A.

Contemporary analytical methods have the sensitivity required for Ochratoxin A detection and quantification, but direct application of these methods on real samples can be rarely performed because of matrix complexity. Thus, efficient sample pre-treatment methods are needed. Recent years have seen the increasing use of artificial recognition systems as a viable alternative to natural receptors, because these materials seem to be particularly suitable for applications where selectivity for Ochratoxin A is essential.

Peptide-based affinity media for solid-phase extraction of Ochratoxin A from wine samples: Effect of the solid support on binding properties.

A suitable sample clean up is a key point in the development of an analytical method. Peptide-based affinity media have recently gained attention in the selective extraction of defined target analytes from complex samples. In this paper we investigated the thermodynamic and kinetic binding properties of different stationary phases (Amberlite IRC-50, Lewatit CNP105, Toyopearl CM-650 M, porous silica gel beads and micrometric glass beads) functionalized with a hexapeptide sequence binding the Ochratoxin A.

Comparison of binding behavior for molecularly imprinted polymers prepared by hierarchical imprinting or Pickering emulsion polymerization.

The aim of this study was the evaluation of the binding performances and selectivity of molecularly imprinted beads prepared toward several penicillins (i) by hierarchical bulk polymerization in the pores of template-grafted silica microbeads (hMIPs) and (ii) by Pickering emulsion polymerization in the presence of template-decorated silica nanobeads (pMIPs). 6-Aminopenicillanic acid was chosen as the common fragmental mimic template. Both approaches produced micron-sized polymeric beads with good recognition properties toward the target ligands whereas the selectivity pattern appeared quite different.

A multiplex chemiluminescent biosensor for type B-fumonisins and aflatoxin B1 quantitative detection in maize flour.

A multiplex chemiluminescent biosensor for simple, rapid and ultrasensitive on-site quantification of aflatoxin B1 and type B-fumonisins in maize samples has been developed. The biosensor integrates a multiplex indirect competitive lateral flow immunoassay (LFIA) based on enzyme-catalyzed chemiluminescence detection and a highly sensitive portable charge-coupled device (CCD) camera, employed in a lensless "contact" imaging configuration. The developed assay requires a simple extraction of the analytes from maize flour samples followed by their detection with a 30 min assay time.

Determination of ochratoxin A in Italian red wines by molecularly imprinted solid phase extraction and HPLC analysis.

An extraction method based on molecularly imprinted polymer prepared through a mimic template approach was used for the determination of ochratoxin A in 17 red wines from different geographical regions of Italy. Sample loading (wine sample diluted 1:1 with 1% v/v aqueous solution of PEG 8000), washing (2 mL water/acetonitrile 4:1 v/v), and elution (2 mL of acetonitrile/acetic acid 98:2 v/v) conditions allowed the optimization of the extraction method, capable of preconcentrating ochratoxin A below the maximum permitted level of 2 ng/mL. Under optimized conditions, recoveries of ochratoxin A from spiked samples ranged from 88 to 102% with sample volumes up to 20 mL.

Optimization of a lateral flow immunoassay for the ultrasensitive detection of aflatoxin M1 in milk.

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 20 ng L(-1), IC50 99 ng L(-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.

A lateral flow immunoassay for the rapid detection of ochratoxin A in wine and grape must.

A one-step lateral flow immunoassay was developed for semiquantitatively detecting ochratoxin A (OTA) in wines and grape musts. Matrix-matched calibration curves carried out in blank wines showed a detection limit of 1 μg L(-1) and IC(50) of 3.2 μg L(-1).

An innovative approach to molecularly imprinted capillaries for polar templates by grafting polymerization.

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.

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.

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.

Lateral-flow immunoassays for mycotoxins and phycotoxins: a review.

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.

A connection between the binding properties of imprinted and nonimprinted polymers: a change of perspective in molecular imprinting.

In the current paradigm for molecular imprinting, the imprinted binding sites exist as a consequence of the polymerization process around templates, and the properties of nonimprinted polymers (NIPs) have largely been overlooked. Thus, nothing can be affirmed a priori concerning the binding properties of NIPs. We propose an alternative view where the imprinting effect is due to the presence of a template molecule that enhances the pre-existing binding properties of a polymer.

Binding behaviour of molecularly imprinted polymers prepared by a hierarchical approach in mesoporous silica beads of varying porosity.

One of the most interesting methods for preparing molecularly imprinted polymers with controlled morphology consists in filling the pores of silica beads with an imprinting mixture, polymerizing it and dissolving the support, leaving porous imprinted beads that are the "negative image" of the silica beads. The main advantage of such an approach consists in the easy preparation of spherical imprinted polymeric particles with narrow diameter and pore size distribution, particularly indicated for chromatographic applications. In this approach it has been shown that the resulting morphology of polymeric beads depends essentially on the porosity and surface properties of the silica beads that act as microreactors for the thermopolymerization process.

Development of a quantitative lateral flow immunoassay for the detection of aflatoxins in maize.

An immunoassay-based lateral flow device for the quantitative determination of four major aflatoxins in maize has been developed. The one-step assay has performance comparably with that of other screening methods, as confirmed by the intra- and the inter-day precision of the data (RSD 10-22%), and can be completed in 10 min. Quantification was obtained by acquiring images of the strip and correlating intensities of the coloured lines with analyte concentration by means of a stored calibration curve carried out by diluting aflatoxins in the extract from a blank maize sample.