Biotest, quantitative

Principle Biosensors consist of paper matrixes and tissue enzyme preparations, often the pure enzyme AChE or AChE-containing cells. As seen in Fig.l, main scheme of the preparation technology and procedure includes (i) the preparation of same kinds of biotests-biosensors, which are paper matrixes impregnated with tissue preparation of AChE and covered by polymer film. (ii) biochemical reactions of the AChE activity with and without inhibitors tested and (iii) the photometric analysis of the samples for quantitative estimation of the biochemical reactions. 

The quantitative estimation of biotests reaction can be expressed in terms of optical density (D) or in terms of factor of reflection coefficient (Kref) ... 

The use of the 96-cells plate and microplate photometers represents a convenient and fast way of quantitative photometric analysis of reactions of the chemical tests and biotests made on the basis of paper materials. The firm microplate photometers are supplied with the necessary software and systems of scanning a plate which carry out not only one-wave, but also the multiwave photometric analysis, that will enable us to increase the accuracy of the analysis. 

The problem of toxic subjects detection in the tested objects can be solved by two options chemical analysis, for revealing separate toxics, or their products, and biotesting with the result of the tested samples toxicity degree indication without identification of the agent. Qualitative and quantitative chrmical/analytical methods allow with the higher accuracy and, in some cases, rapidly detect presence of the separate toxics or their products in the tested objects. It is important for the regular detection of the different pollutions of any agents in the tested objects. 

Nendza, M., Seydel, J.K. (1988) Quantitative structure-toxicity relationship for ecotoxicologically relevant biotest systems and chemicals. Chemosphere 17, 1585-1602. 

Biotests for the detection and quantitative measurement of C. measure one of the following 1. stimulation of cell division in tissue cultures, e.g. in tobacco or soybean callus tissue 2. enlargement of cells in the leaf disc test, often with bean or radish leaves 3. inhibition of the loss of chlorophyll from detached leaves 4. promotion of seed germination in the dark. 

Oat coleoptie last Arena test a biotest for the quantitative determination of auxins, which is carried out as follows. The tip of the coleoptile is cut off, and the cotyledon within it is removed by pulling on its base. An agar block with the test substance is set on one side of the coleoptile stump. Auxin diffuses into the side of the coleoptile covered by the agar and, due to the one-sided stimulation of growth, causes it to bend. The angle of the bend is a function of the auxin concentration. 

The performance of an earlier Biotest RCS air sampler was studied by Clark et al. where they found that this device was inefficient for sampling particles less than 5 pm and the effective sampling rate given by the manufacturers was incorrect. For this reason the authors advised that caution should be exercised in using this sampler for quantitative assessment of micro-organisms in air. 

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