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An immunochromatographic test system based on the indirect competitive format has been developed for the rapid control of cyanotoxin microcystin-LR (MC-LR) in drinking water. To increase the assay sensitivity, a hydroquinone-based reduction of silver ions on the surface of gold nanoparticles as part of the immune complexes formed on the immunochromatographic membrane has been carried out. This stage allows for the enhancement of the colouration in test strip zones. The developed test system is characterised by an instrumental limit of detection of 0.05 ng/mL, a cut-off of 0.5 ng/mL, and a working range of the detectable concentrations of 0.08–0.42 ng/mL. The assay duration was 17 min. The applicability of the test system for MC-LR detection in drinking water is demonstrated. The assay recoveries vary from 90% to 120%. [ABSTRACT FROM AUTHOR]

Maximum permissible levels of mycotoxins in baby food may be 1% of those in ordinary food. Therefore, highly sensitive methods of mycotoxin control are in demand. To detect such low amounts, expensive instrumental methods are commonly used. Advantages of immunochromatographic analyses are their low cost and simple sample preparation; however, their sensitivity needs to be increased to contend with instrumental methods. A scheme for competitive immunochromatography with indirect labelling was implemented and developed for the detection of mycotoxin zearalenone (ZEA). Two separate reagents were used for the assay, namely free specific antibodies and antispecies antibodies conjugated with gold nanoparticles. This made it possible to simultaneously increase the sensitivity of the assay and the reliability of measurements. The instrumental detection limit of ZEA in baby food was 5 pg/mL (100 pg/g). Thus, the sensitivity attained is comparable with liquid chromatography characteristics. The duration of the analysis was 17 min. [ABSTRACT FROM AUTHOR]

The use of excessive antibiotics in medical treatment and animal breeding has led to their prevalence in the environment and foods. Thereby, rapid, cheap, and sustainable techniques are required to detect and control the potential risk related to antibiotics. Actually, immunoassays have wide applications for this purpose, and improved assay formats with enzymatic, fluorescent, nanodispersed, and other tracers have enhanced the efficiency of the technique. However, there are several shortcomings of immunoassay due to the protein nature of antibodies. Thereby, molecular imprinting technology has evolved as growing artificial analytical receptor for molecular recognition with binding properties similar to natural antibodies. Molecularly imprinted polymers (MIPs) are defined as "plastibodies" or substitutes for antibodies in immunoassays. This review gives a general overview of the application of molecular imprinting to analytical systems, its state of art, and perspective. The application of MIP-based assays in the detection of antibiotics in food and environmental samples is explored herein. [ABSTRACT FROM AUTHOR]

Arsenic is toxic, so being able to detect and monitor arsenic in aqueous environments is important. Here, we report a biosensor for As3+ (Arsenic (III)) which uses a glassy carbon electrode modified with Ag-Au alloy NPs (i.e. Silver and gold alloy nanoparticles) and loaded with an aptamer. The electrode contains apta deep trapped Ag-Au alloy NPs, and the detection method employs cyclic voltammetry and differential pulse voltammetry. Captured As3+ ions undergo electrochemical reaction, producing a significant increase in the current which is observed in the voltammetry curves. This current increase is a result of the electrocatalytic properties of the NPs. The electrode is used for the determination of As3+ in real water samples. The activity curve is linear for As3+ concentrations of 0.01µg/L to 10 µg/L, and the detection limit is 0.003 × 10−3µg/L. The operation of the biosensor is reproducible, stable, and selective, and the biosensor performs well in determining As3+ in water from natural water courses, lakes, and wells. [ABSTRACT FROM AUTHOR]

The paper describes the first use of silanized semiconductor core-shell quantum dots as fluorescent labels for macromolecule, C-reactive protein determination in blood plasma. The controlled synthesis of CdSe cores, with successive shells of CdS, CdZnS, ZnS and coating with transparent, stable, and inert silica shell, provides quantum dots with a narrow emission band, high quantum yield, and prolonged signal stability. Finally, the quantum dots were conjugated with specific antibodies via carboxylic groups on the silica surface. The method was further used for the immunochromatographic assay of C-reactive protein, a diagnostically important inflammatory biomarker. Assays with both the fluorescent QDs and a widely used colloidal gold label were developed in parallel and compared. The silanized quantum dots provide a more sensitive assay with a detection limit of 1 ng/mL for C-reactive protein in standard solutions, whereas the common assay has a detection limit of 10 ng/mL. The possibility of quantitative evaluation of analyte content by a portable device was demonstrated; the accuracy of the measurements was in the range of 5%–10%. The tests were used to determine C-reactive proteins in human plasma samples. The selected optimized protocol for these samples is based on a 4-fold dilution. The final working range of the assay, 4–1,200 ng/mL, covers practically all important interval of C-reactive protein values for the characterization of acute, chronic, and local inflammatory processes. Due to their high physical stability and inertness as well as intense, stable, and reproducible fluorescence, silanized quantum dots may be applied for high-sensitive assays for different analytes. [ABSTRACT FROM AUTHOR]

Food colorants are inalienable part of human life. Since ancient times, they have become firmly established and have undergone a number of changes. During this time, the attitude towards them has changed. The desire to color the food now raises questions about the various side effects of their use. With the development of methods of toxicology and obtaining data on the toxicity of food coloring, restrictions and standards for their content in food have emerged. The development of methods for the analysis of dyes in various food products is becoming increasingly in demand. Development of screening immunoanalytical methods such as enzyme-linked immunoassay and immunochromatographic one suitable for simultaneous analysis of a large number of samples at the same time allows to avoid serious costs when operating the chromatographic equipment. Reduction of the analysis time and simple sample preparation is what unites immunoassay techniques. This review shows the possibilities of modern immunoanalytical methods for analyzing samples and determining food dyes belonging to different classes. [ABSTRACT FROM AUTHOR]

Rapid non-laboratory screening of plants for pathogenic viruses crucially influences crop yields in modern agricultural technologies. The aim of this study was to develop a highly-sensitive lateral flow immunoassay (LFIA) for rapid detection of potato leafroll virus (PLRV), an infectious agent of one of the most widespread potato diseases. The proposed LFIA combines the formation of sandwich immune complexes with gold nanoparticles (GNP) as labels and silver enhancement. The enhancement stage was realized using mixture of silver lactate and hydroquinone and subsequent addition of chloride-containing buffer to stop silver reduction. LFIA with silver enhancement was 15 times more sensitive (detection limit 0.2 ng/mL; 15 min) compared with conventional LFIA (detection limit 3 ng/mL; 10 min). The enhanced LFIA detected PLRV in leaves’ extracts of infected potato in dilutions higher than enzyme-linked immunosorbent assay. [ABSTRACT FROM AUTHOR]

A gold nanoparticle (AuNPs)-catalysed chemiluminescence (CL) method is developed for the analysis of As3+cations by detecting the enhancement of the luminol–H2O2reaction by AuNPs. AuNPs of different sizes were prepared by a chemical method. The size and shape of these nanoparticles were determined by transmission electron microscopy. The various parameters of the reaction media such as the pH and the concentration of H2O2and luminol were optimised. The enhancement of the CL intensity may be as a result of energy transfer by the AuNPs or plasmon-induced enhancement. The interaction of the AuNPs with As3+amplified the CL signal. This amplified CL was used to detect As3+in real water samples. The linear region of the calibration curve from 0.3 to 4 µg/L shows that this is a suitable method for the detection of low concentrations of arsenic (III). [ABSTRACT FROM AUTHOR]

A novel synthesis of gold nanoparticles is reported by chemical reduction of chloroauric acid with polyethylenimine and trisodium citrate. The use of polyethylenimine and trisodium citrate provided a convenient route to produce gold nanoparticles with diameters between 3.7 and 11.8 nm. The resulting nanoparticles were characterized by ultraviolet-visible spectroscopy, transmission electron microscopy, and zeta potential measurements. Transmission electron microscopy provided imaging of the shape and size of the nanoparticles. In order to characterize the solubility of the gold nanoparticles for application as an electrochemical sensor, the zeta potential, hydrodynamic diameter, electrophoretic mobility, and surface area-to-volume ratio were determined. The gold nanoparticles were incorporated on a glassy carbon electrode to produce an amperometric sensor for the determination of arsenic. [ABSTRACT FROM AUTHOR]

In this study, male rats were intragastrically exposed to fullerene C60for 1-day and 30-day periods at daily doses of 2000 and 250 mg/kg of body weight, respectively. Fullerene was detected in organs and tissues by HPLC after the extraction from biosamples with toluene. No statistically significant differences in hematological and biochemical parameters of control and treated rats were found after single and multiple administrations. Throughout the observation periods no lethality was observed. At necropsy, no pathomorphological changes in internal organs were recorded. Fullerene was found in stomach, small intestine, liver, lungs, spleen, kidneys, and blood. The amounts of the detected fullerene in comparison to the administered doses are far smaller which is the evidence of its efficient excretion. Hence, it can be assumed that fullerene nanoparticles penetrate from the gastrointestinal tract of rats into the bloodstream and translocate into secondary organs with no pronounced toxic effect in experimental conditions studied. [ABSTRACT FROM PUBLISHER]

An immunochromatographic test system was developed for rapid detection of the levels of specific IgG antibodies toBrucella abortuslipopolysaccharide, as a tool for diagnosis of brucellosis in cattle. The pilot test strips were examined using blood sera from sick (78 samples) and healthy (35 samples) cows. The results obtained by immunochromatographic assay, using a portable optical densitometer for digital video detection, correlate well with the results obtained by immunoenzyme assay and are in agreement with the results of the disease diagnosis. The new test system allows detection of antibodies within 10 min and can be proposed as an alternative to the methods available for serodiagnosis of brucellosis. [ABSTRACT FROM PUBLISHER]

A microformat imaging technique in combination with registration of chemiluminescence by a charge-coupled device, CCD camera, were applied for the detection of the herbicide atrazine by two immunoenzyme assay formats – microplate and membrane assays. For the microplate (ELISA) case the detection limit was 95  pg  mL -1 , giving a 9.5-fold enhancement in comparison with a traditional colorimetric assay. The membrane dot blot assay allowed detection of up to 40  pg  mL -1 of atrazine (4.5-fold enhancement). Due to the application of polyelectrolyte carriers for rapid reactants separation the membrane assay may be realized in 15  min. CCD-based registration of signals assures a high reproducibility of measurements; the variation coefficient is in the range 1–7%. The effectiveness of the assays developed for controlling triazine herbicides in mineral and tap water has been demonstrated. [ABSTRACT FROM AUTHOR]

Polyclonal rabbit antibodies against nonylphenol (NP), the main product of nonionic surfactants destruction, were obtained and applied for immunoenzyme assay (ELISA). Two approaches to immunogen synthesis were compared. The first was direct coupling of a mixture of NP isomers to the carrier protein by Mannich reaction. The second was formation of amide bonds between 7-( p -hydroxyphenyl)heptanoic acid (HHA), a linear carboxylated analog of NP, and the carrier protein. Anti-HHA antibodies showed a low affinity to technical NP, whereas with Mannich synthesis it was possible to generate antibodies specific to branched NP molecules. An indirect competitive ELISA was developed based on the anti-NP antibodies. The detection limit of the analysis is 10 ng/mL, with a total duration of around 3 h. The developed ELISA can be applied for group-specific determination of nonionic surfactants and their toxic metabolites. The possibility of NP detection in environmental water matrices using the proposed ELISA without loss of sensitivity is explored. [ABSTRACT FROM AUTHOR]