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New biosensor provides improved infection detection

Biotech researchers develop rapid, cost-cutting method to identify bacteria in wounds

For several years, researchers have been trying to formulate the best way to quickly detect an infection in open wounds without relying on time-consuming tests. Bacterial infection numbers among the world’s leading causes of death, and thus it must be quickly detected to proceed with effective antibiotic treatment. Anita Shukla, assistant professor of engineering and molecular pharmacology, physiology and biotechnology, worked with Roya Sheybani, former Hibbitt Engineering Post-Doctoral Fellow, to develop a sensor that could perform this kind of rapid identification of wound bacteria.

Previous attempts at developing such infection detection biosensors have resulted in lengthy identification times, insufficient sensitivity to bacteria and dependence on unwieldy equipment that makes sensors difficult to wear, according to the article.

Some sensors measure the acidity of the wound, while others monitor the number of bacteria that attach themselves to the sensor, Shukla said.  “Typically with these kinds of sensors, (researchers) are using just one approach,” she added. Their research couples the two factors to provide more information, as acidity alone does not provide much information about the wound.

A shift in acidity could just be a response to a body change, but “when you couple it with an attachment sensor, it very specifically tells you that bacteria are attaching, and the pH can tell you a little more about what kind of bacteria these are.”

The sensor’s method for detecting bacteria is “very effective,” said Darius Rackus, a PhD student at the University of Toronto who was cited in the researchers’ article. “(The sensor) is measuring two very different things,” Rackus said. In addition to monitoring the presence of bacteria in the wound through cell attachment, the sensor can also offer information about the growth of these bacteria through the pH measurement, Rackus added.

To monitor bacterial cell attachment, the sensors measure how easily current passes through the tissue, Sheybani said.  In the wound,  “a small alternating current can be applied across the electrodes through a range of frequencies,” allowing the researchers to observe how much bacteria hinders the current, Sheybani said. “The presence of bacteria in the solution and their subsequent attachment to the sensor surface causes a shift in the measured impedance,” and these measured values are correlated to bacteria concentration, she added.

Though the device is a significant advancement in the field of biotechnology, its use could be limited at this level of development. The device was built on glass, but to measure bacteria in a live wound, it would need to work on a more flexible substance, Shukla said. Most of the processes used to create the sensor can be applied to soft materials like bandages, she added. “Our hope and our hypothesis is that we won’t run into major issues, but you never know — there could be problems in transferring it to a more biomedically relevant substrate.”

The sensor may not be ready for testing in animals just yet, Rackus said. But hopefully, the sensor will be embedded in soft materials and can progress to live testing, Shukla said.

Shukla and Sheybani attempted to limit the sensor’s cost. “You can imagine that would be important for using it in a setting where you can’t really afford expensive equipment,” Shukla said. “The goal eventually is to also make the sensor output completely wireless so that you don’t even need to carry around any special equipment.”


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