New biosensor detects bacterial growth

Researchers at the University of Michigan have recently invented a new type of biosensing device that allows the measurement of bacterial growth and drug sensitivity without the use of a microscope. The results were published in the January 15 issue of the Journal of Biosensors and Bioelectronics.

Scientists call this device an "AMBR sensor," which uses a magnetic bead that rotates asynchronously in a magnetic field. Any material attached to this bead will reduce its rotational speed. In this study, the researchers attached rod-shaped E. coli to magnetic beads and then detected them with an AMBR sensor.

"When a single bacterium is attached... it will greatly hinder the magnetic beads, slowing down the rotation rate of the magnetic beads to the original quarter," explains Professor Raoul Kopelman who led the study. "If bacteria grow up a little longer, The barrier force will continue to increase and the speed will change accordingly, so we can measure this nanoscale growth change of bacteria."

Using the same principle, the device can also be used to detect the susceptibility of bacteria. When bacteria stop growing under the influence of drugs, the magnetic bead speed changes, so researchers can know in a matter of minutes whether the drug has an effect on the bacteria.

"In this way, we can detect changes in bacterial growth as small as 80 nanometers, which is far better than an optical microscope - the resolution of the microscope is about 250 nanometers," said the first author of the article, Paivo Kinnunen. This method can be applied to any micron or nano size change detection."

Researchers say that this new type of bio-sensing device will help speed up the treatment of bacterial infections.