Bacteria visualized with remarkable clarity thanks to new technique

Shaopeng Wang
Shaopeng Wang is a researcher in the Biodesign Center for Bioelectronics and Biosensors. He is the corresponding author of the new study.

An escalating arms race between disease-causing bacteria and the antibiotic weapons humans have designed to fight them, continues. Disturbingly, pathogenic microbes are often outwitting our best efforts, developing resistance to many mainline antibiotics. Overuse of broad-spectrum antibiotics in medicine and agriculture is driving bacterial resistance to these life-saving tools.

In a new study, researchers at the Biodesign Center for Bioelectronics and Biosensors outline an innovative means for studying bacteria. The new method involves a novel form of microscopy called Electrical Impedance Microscopy (EIM). By applying a low frequency electrical potential to a sample, the technology is able to image not only bacterial colonies but individual bacteria with startling resolution. The method is based on the fact that bacterial cells respond to electrical fields in particular ways, based on cell size and shape, internal structure and conductivity. 

The simple imaging approach can be used to identify resistant bacteria associated with disease, delivering accurate results more rapidly at lower cost. The method also avoids the laborious sample preparation steps common with existing assays, which often rely on enzymes and primers.

Fenni Zhang
Fenni Zhang is an assistant research professor in the Biodesign Center for Bioelectronics and Biosensors. She is the project lead for the current study.

The study highlights the use of EIM to monitor the response of E. Coli cells to two different antibiotics. Corresponding author Shaopeng Wang emphasizes the power of EIM for ferreting out fine details of bacterial responses, including the ability to rapidly pinpoint cells displaying resistance:

“Our research focus is on developing new imaging capabilities to address challenging issues in biomedical research and the healthcare industry,” Wang says. “This paper reports our development of a simple, label-free optical imaging method for visualizing individual bacterial responses to antibiotics.”

“Fenni Zhang, a postdoc in our group, who was recently promoted to assistant research professor, is the technical lead of the project,” Wang says. “We dedicate this paper to Prof. NJ Tao, who supervised the project and edited the early draft of the paper.”

The research recently appeared in the journal ACS Sensors. The special issue of the journal was in commemoration of Tao, who co-authored the study and directed the Center for Bioelectronics and Biosensors prior to his death earlier this year.

Richard Harth