Arrays learn to multitask

US researchers have increased the information density of microarrays without further shrinking the dimensions of the spots. Instead, they used a combinatorial approach that involves multiple usage of each spot, known as multiplexing. 

Grant Willson’s team at the University of Texas at Austin demonstrated the new technology in an assay designed to screen for potentially carcinogenic mutations in the protein p53, using 29 different test probes (each designed to detect one specific mutation), plus two probes covering different parts of the uncompromised sequence (wild type). 

Instead of attaching these 31 different probes to an equal number of spots on a microarray, the researchers used only five spots and applied each of the probes to a specific combination of these. For a quick and simple assignment, they numbered the probes and converted the numbers to 5-digit binary numbers. Thus the first sample was 00001, and the 31st one 11111. Spots were paired up with the positions of the binary number, and the binary digit determined whether given probe would be applied to a given spot. For example, probe 7, or 00111 would be present in spots 3, 4, and 5 only.  

Biotech consultant Alrik Koppenh?fer from Heidelberg, Germany, sees a bright future for such systems: ’Multiplexed arrays could be the next generation in expression profiling,’ he said. ’As an investor in the biotech industry, I would look more closely at the commercialisation of this promising technology, which could capture a fair share in a more than one-billion-dollar market.’ Michael Gross