A
new type of electronic sensor that might be used to quickly detect and classify
bacteria for medical diagnostics and food safety has passed a key hurdle by
distinguishing between dead and living bacteria cells.
Conventional
laboratory technologies require that samples be cultured for hours or longer to
grow enough of the bacteria for identification and analysis, for example, to
determine which antibiotic to prescribe. The new approach might be used to
create arrays of hundreds of sensors on an electronic chip, each sensor
detecting a specific type of bacteria or pinpointing the effectiveness of
particular antibiotics within minutes.
"We
have taken a step toward this long-term goal by showing how to distinguish
between live and dead bacteria," says Muhammad Ashraful Alam, Purdue
University's Jai N. Gupta Professor of Electrical and Computer Engineering.
"This is important because you need to be able to not only detect and
identify bacteria, but to determine which antibiotics are effective in killing
them."
Findings
are detailed in a research paper appearing this week in Proceedings of the
National Academy of Sciences. The paper was authored by doctoral student Aida
Ebrahimi and Alam. The droplet sensor evolved from a device originally designed
to detect small concentrations of negatively charged DNA molecules in research
that began about four years ago, Ebrahimi says.
"We
did not anticipate that the sensor could be used to tell live and dead bacteria
apart — it was a chance observation that eventually led us to this elegant way
of measuring cell viability," she says.
Posted by Dr. Tim Sandle