"When one bacterium gets attached, it's hanging out there like a little hotdog, and it changes the drag tremendously, slowing down the rate of rotation by a factor of four," said Kopelman. "If the bacterium grows even a tiny bit, the drag increases even more, and we can monitor that nano-growth by observing changes in the rate of rotation."
"The method can detect growth of as little as 80 nanometers, making it far more sensitive than even a powerful optical microscope, which has a resolution limit of about 250 nanometers," said graduate student Paivo Kinnunen, one of the paper's lead authors, who is
also working at Life Magnetics while completing his studies. (While the AMBR sensor does not require a microscope, one was used in the current study to confirm results).
The U-M group demonstrated that the sensor not only can monitor the growth of a single bacterium throughout its life cycle and over multiple generations, but it can also determine when an individual bacterium stops growing, in response to treatment with an antibacterial drug, for instance.
"You can basically tell, within minutes, whether or not the antibiotic is working," said Kinnunen.
In the near future, "we expect it will be possible to make the determination even quicker," said graduate student Irene Sinn, the paper's other lead author. "This is something we are actively working on."
The device also can be used for monitoring the growth and drug susceptibility of other types of cells, said Kinnunen. "The sensor is very sensitive to small changes in growth, so this method can be applied to any applications in the microscale or nanoscale where there are small changes in size. That includes the growth of yeast and cancer cells as well as bacteria."
The technology could have far-reaching implications, said McNaughton.
"At Life Magnetics we are very excited and optimistic about leverag
|Contact: Nancy Ross-Flanigan|
University of Michigan