Multi-residue detection of benzodiazepines by ELISA based on class selective antibodies

A molecularly imprinted polymer based chemiluminescence array sensor for one-step determination of phenothiazines and benzodiazepines in pig urine

The residues of phenothiazines and benzodiazepines in foods of animal origin are dangerous to consumers. For inspection of their abuses, this study for the first time reported on the use of a chemiluminescence array sensor for the simultaneous determination of four phenothiazines and five benzodiazepines in pig urine. Two molecularly imprinted polymers were coated in different wells of a conventional 96-well microtiter plate as the recognition reagents. After sample loading, the absorbed analytes were initiated directly by using an imidazole enhanced bis(2,4,6-trichlorophenyl)oxalate-hydrogen peroxide system to emit light. The assay process consisted of only one sample-loading step prior to data acquisition, so one test was finished within 10 min. The limits of detection for the nine drugs in the pig urine were in a range of 0.1 to 0.6 pg/mL, and the recoveries from the fortified blank urine samples were in a range of 80.3 to 95%. Furthermore, the sensor could be reused six times. Therefore, this sensor could be used as a simple, rapid, sensitive and reusable tool for routine screening for residues of phenothiazines and benzodiazepines in pig urine.

Production of monoclonal antibody against clonazepam for immunoassay of benzodiazepine drugs in swine tissues

The objective of the present study was to produce a generic monoclonal antibody for immunoassay of residues of benzodiazepine drugs in swine tissues. Clonazepam was used to synthesize a hapten that was coupled to bovine serum albumin as an immunogen for the production of monoclonal antibody. Results showed that the obtained monoclonal antibody was able to recognize five benzodiazepine drugs simultaneously (clonazepam, flunitrazepam nitrazepam, diazepam, and oxazepam). The cross-reactivities were in the range of 24-100% and the limits of detection were in the range of 0.2-1.5 ng mL(-1) depending on the drug. Then a competitive indirect enzyme-linked immunosorbent assay was developed to determine the residues of five benzodiazepines in swine tissues (muscle, liver and kidney). The recoveries of five analytes from the fortified blank samples were in the range of 74.5-96.5% with coefficients of variation lower than 16.7%. Therefore, this immunoassay could be used as a rapid and simple method for the screening of residues of five benzodiazepine drugs in animal-derived foods.

Parts per trillion detection of 7-aminonitrazepam by nano-enhanced ELISA

It is challenging to detect 7-aminonitrazepam (7-ANZP) residue in animal tissues simply and sensitively by the enzyme-linked sorbent immunoassay (ELISA) method. This paper demonstrates that utilizing a bioconjugate of gold nanoparticles and enzyme-labeled antibody as a signal probe increases the sensitivity of a traditional ELISA for 7-ANZP by nearly 20 times. The sensitivity of this ELISA for 7-ANZP was 5.6 pg/mL in buffer, and the limit of detection (LOD) of 0.18 μg/kg for 7-ANZP in urine could be achieved after the urine samples were simply hydrolyzed and diluted by buffer. This simple and sensitive method has potential application for improving the sensitivity of ELISA methods against various small molecules.

Multiplex bioanalytical methods for food and environmental monitoring

Recent advances in miniaturization of analytical systems and newly emerging technologies offer platforms with greater automation and multiplexing capabilities than traditional biological binding assays. Multiplexed bioanalytical techniques provide control agencies and food industries with new possibilities for improved, more efficient monitoring of food and environmental contaminants. This review deals with recent developments in planar-array and suspension-array technologies, and their applications in detecting pathogens, food allergens and adulterants, toxins, antibiotics and environmental contaminants.

A simple, sensitive, rapid and specific detection method for Bisphenol A based on Fluorescence Polarization Immunoassay

A rapid, sensitive, specific and simple method based on Fluorescence Polarization Immunoassay (FPIA) was developed for the quantitative detection of Bisphenol A in water. 4, 4-Bis (4-hydroxyphenyl) valeric acid (BHPVA) was selected as the hapten to produce the immunogen. Fluorescein-labeled Bisphenol A derivatives (tracers) with different structures were synthesized and purified by thin layer chromatography. Based on the polyclonal antibody and tracers, an optimized FPIA method was developed with a detection limit (10% inhibition) of 2 μg L(-1) and a linear working range of 20 to 800 μg L(-1). FPIA was suitable for screening a large number of samples. The recoveries of fortified Tai lake water samples ranged from 91.85 to 102.78%, and tap water samples ranged from 90.36 to 96.01%. The coefficients of variation were all less than 20%. This FPIA method, which did not require a complicated cleanup process, proved to be very useful for the screening of Bisphenol A in environmental water samples.