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Screening methods for mammalian toxicity Print
If you cannot use QSAR methods then rapid screening test may help you to decide whether you will need to have animal tests.  These tests are not all validated and can only be used for registration in limited case but they can give you a rapid indication of whether your chemical may be toxic and this will allow you to decide whether to continue with more expensive animal testing.

 

This page will provide guidance about the tests available and will also report some research into further developing rapid screening methods using lab on a chip technology.

 

 


Lab on a chip screening tests

There are different types of micro-screening tests. Some are whole cell based, using mammalian or yeast cells and other are based on substrate affinity to specific compounds (i.e. imprinting polymers, immunoassays, electrochemical assays, enzyme-based biosensors and amperometric sensors)

  

Develop a micro-scale chip for an easy toxicity screening

Developing a microfluidic device is a big challenge. The aim is an easy and low cost system for screening toxicity for chemical manufactures (see flowchart).

 

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A prototype microfluidic chip using fluorescent yeasts for rapid detection of toxic compounds was developed. Using glass-glass or glass-PDMS micro devices. Below are pictures of both types of microfluidic devices. The cells are adapted well in the microfluidic system and exposed to potential hazardous chemicals. In case of toxicity, the yeasts would release fluorescence and the chemcals can be assessed for its toxicity. Detection of fluorescence emission is carrying on under light and fluorescent microscope.

 

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The reporter used in the prototypes micro-screening, consisted of recombinant yeasts with a fusion of the DNA damage-inducible promoter from an endogenous DNA repair gene, RAD54, with a gene encoding a yeast enhanced green fluorescent protein (yEGFP). The yeast are kindly supplied by Gentronix (www.gentronix.co.uk) which express a yeast enhanced GFP under the control of a copy of the promoter from the native yeast gene RAD54. The yeast Saccharomyces cerevisiae containing fluorescent markers are ideal candidates for the microfluidic screening systems as fluorescence is emitted without the need to add any reagents. There is a good number of different toxicity screening methods using recombinant yeasts, almost all using 96 well plates, microplate readers and its robotics. 

 

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The microfluidic devices are either of multiparallel channels or micro-chambers. You can see below pictures of both types of yeasts inside the channels and chambers with ligh and fluorescent miscrocopy. Multiparallel channels offer more possibilities to screen different compounds with diffrent concentrations at the same time, although in micro-chambers the yeasts are very easy to be immobilised.

 

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Last Updated ( Thursday, 18 December 2008 )
 
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