A simple mixture of four commercially available compounds can be used to detect several biomolecules at the same time, say Swiss scientists.

Kay Severin at the Federal Polytechnic School of Lausanne (EPFL) and colleagues have developed a multicomponent indicator displacement assay (MIDA) that can be used as selective and sensitive detector for biomolecules.

Indicator displacement assays (IDAs) work on the basis of an analyte molecule binding to a receptor and displacing an indicator molecule, causing a change in its optical properties. In MIDAs, several receptor-indicator combinations are used simultaneously. The bound and free molecules are different colours, so each analyte gives rise to a characteristic ultraviolet-visible spectrum that can be used to identity and quantify the analyte.

The MIDA developed by Severin's team used a simple rhodium complex as the receptor, combined with three commercially available dyes as indicator molecules.  The researchers used this system to detect the biologically important molecules adenosine triphosphate, cyclic adenosine monophosphate and pyrophosphate in the same solution. 

'The assay is very easy to perform,' said Severin, 'it just requires mixing of commercially available substances and a low-tech analysis method, such as UV/Vis spectroscopy.'

Severin plans to develop MIDAs for the detection of other biologically interesting molecules. He also hopes to extend the study to a real-world application, such as monitoring the activity of an enzyme.

Edward Morgan