Saturday, 4 January 2014

Microfluidic chip sorts 'good' bacteria from 'bad' bacteria

Sometimes the difference between harmless and harmful bacteria is miniscule. For example, with Escherichia coli, the difference between E. coli O157:H7 and less harmful strains are detectable only at the molecular level.

Determining whether or not bacteria are harmful usually requires growing cultures from food or infected patients. This is a time-consuming process that must be carried out in a laboratory. To overcome this, Scientists at Arizona State University's Department of Chemistry and Biochemistry, in the College of Liberal Arts and Sciences, have developed a new device that could significantly speed up the identification process for harmful bacteria and other microorganisms. The team, led by Professor Mark A. Hayes, hopes to create handheld, battery-operated devices that could deliver answers in minutes, instead of days.

Identification takes place within a microscopically small channel in a chip made from glass or silicone polymer. The microchannel features saw-tooth shapes that allow researchers to sort and concentrate microbes based on their unique electrical properties. The phenomenon that makes this work is called dielectrophoresis, which involves an applied voltage that exerts force upon the bacteria. The technique is based on the fact that different bacterial strains possess subtle, but telltale differences in the proteins and other molecules that they express on their surface.

Based on the work so far, the research team plan to create cheap, portable devices that would enable point-of-care or field based analysis.

The new technology has been described in the journal Analytical and Bioanalytical Chemistry, in a paper titled "Differentiation of Escherichia coli serotypes using DC gradient insulator dielectrophoresis".

Posted by Tim Sandle