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one-step immunochromatographic method for the detection of the diphtheria toxin in different water samples (phosphate buffer, milk, and human nasopharyngeal swab) was developed using a conjugate of monoclonal antibodies labeled with colloidal gold. The detection limit of diphtheria toxin was 10 ng/ml, the time of the analysis was 15 min. The use of silver to enhance the reaction sensitivity and scanning equipment to evaluate the immunochromatography results decreased the detection limit to 1.25 ng/ml. [ABSTRACT FROM AUTHOR]

A method of simultaneous analysis of staphylococcal enterotoxins using hydrogel-based microarrays (biochips) has been developed. The method allows simultaneous quantitative detection of seven enterotoxins: A, B, Cl, D, E, G, and I in a single sample. The development of the method included expression and purification of recombinant toxins, production of panels of monoclonal antibodies (mAbs) against the toxins, and design and manufactoring of an experimental biochip for the screening of mAbs and selection of optimal pairs of primary and secondary antibodies for each toxin. The selected mAbs have high affinity toward their targets and no crossreacthity with unrelated enterotoxins. Finally, a diagnostic biochip was designed for quantitative analysis of the toxins, and the analytical protocols were optimized. The sensitivity of the detection reached 0.1-0.5 ng/ml, depending on the type of enterotoxin. The evaluation of the resulting biochip using spiked food samples demonstrated that the sensitivity, specificity, and reproducibility of the proposed test system fully satisfy the requirements for traditional immuno analytical systems. The diagnostic biochips manufactured on reflecting metal-coated surfaces shortened the time of analysis from 17 to 2 h without loss of sensitivity. The method was successfully tested on samples of food and biological media. [ABSTRACT FROM AUTHOR]