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U of Toronto Team Develops Next-Gen POC Pathogen Identification Chip


A team of researchers at the University of Toronto has developed the next-generation of a chip-based platform for the identification of infection-causing bacteria.

And while Xagenic, a Canadian molecular diagnostics firm, is commercializing an earlier version of the same platform, the firm could also sell the newer, higher-throughput chip in the future, according to Shana Kelley, chief technical officer at Xagenic and a professor at the University of Toronto.

In a paper published this month in Nature Communications paper Kelley and colleagues describe the development of an integrated circuit that was able to detect bacteria at concentrations found in patients presenting with a urinary tract infection.

A specific highlighted achievement was the ability of the integrated circuit to accommodate a panel of multiple nucleic acid biomarkers, Kelley told BioArray News.

"This was a much, much more multiplexed version of the technology than we had been able to put forward before," Kelley said. "That was the big advance."

According to the paper, Kelley's lab created distinct columns of connected biosensors, and then arrayed rows of channels containing electrochemical solution perpendicular to the columns. Using the resulting two-dimensional array of electrodes they programed transient, solution-based circuits. Samples flown through the channels therefore could be analyzed using multiple sensors, while those same sensors retained shared contacts.

The approach "allows a much higher level of multiplexing than was attainable previously using a small set of contacts," the authors wrote. In the validation study, they used the new multiplexed chips to assess multiple pathogens connected with urinary tract infections, as well as antibiotic-resistance markers, using 30 probes per sensor.

For Kelley's lab, which specializes in devising devices that measure biological activity, the new chip is an improvement over earlier generations of the same platform that measured one bacterium at a time, rather than multiple, different bacteria in each sample.

"To do this higher level of multiplexing, we had to come up with a strategy where we basically didn't want to have to contact every single sensor individually because the chip starts to get big and the contacts get complicated," said Kelley. "That is the real innovation here," she said. "We made a transient circuit by connecting two solutions, and then we can reuse our contacts over and over again, so it really simplifies things."

Kelley's lab is ultimately focused on developing devices that are quick enough and portable enough to be used at the point of care. She said that devices such as the one featured in Nature Communications could be used to quickly identify infections, as well as drug-resistance markers, that would allow physicians to treat their patients more effectively. Currently physicians for the most part rely on culture, which can take several days.

"Timing is an advantage," said Kelley. "We are aiming to complete an assay while a patient is still with a physician, where they can get a test result and be treated appropriately according to those results," she said.

'Down the Path'

According to Kelley, the device featured in Nature Communications is about "three generations beyond" the platform being commercialized by Xagenic. She said that Xagenic might commercialize the newer device, but it is "pretty far down the path with the original chip at the moment."

Xagenic was founded in 2010. The firm received $2.2 million in seed funding at that time from a number of investors (BAN 10/19/2010). Last year, it raised $10 million in Series A financing, and earlier this year, it raised an additional $990,000 (1/31/2012)

The company is commercializing its Amplified Redox Assay, or Aura, platform, which is based on the microelectrode arrays developed in Kelley's lab. Though Kelley serves as CTO for Xagenic, she stressed that they are different entities with different aims.

"We do completely new things at UT that we don't have time to do at Xagenic," said Kelley. Xagenic is "very much focused on commercialization," and "getting one lead product out the door."

To accomplish that, the firm plans to conduct a clinical trial of a pathogen detection assay next year, with the ultimate goal of US Food and Drug Administration clearance. Assuming it achieves this goal, Xagenic intends to introduce a menu of different tests to market. Kelley declined to discuss the content of the firm's planned assays.

Xagenic's interest in the multiplexed POC infectious disease testing market is matched by a number of competitors. Akonni Biosystems, for instance, sells an array-based, point-of-care system called TruSentry that it claims enables the detection of infectious microorganisms and drug-resistant variants; Boulder, Colo.-based InDevr offers pathogen-detection tests on its point-of-care AmpliPhox system; and Newcastle, UK-based QuantumDx is also developing a biochip-based POC device for HIV, tuberculosis, and warfarin sensitivity testing, to name a few (BAN 10/25/2011).

Kelley said that Xagenic's "key differentiator" is that its system supports direct detection, meaning no enzymes are required to conduct the assay.

"That is really a huge advantage when you look at rolling out a product where you want to have room temperature stability," she said. "It's easier to do that if you don't have anything biological interfering with the assay."

She also said she believes such tests will transform the infectious-disease testing landscape, away from larger, centralized labs, and toward the field.

"We are going to be taking reference labs out of the equation," said Kelley. "There are a lot of groups out there thinking about how to bring POC technologies to the market," she said. Kelley added that larger labs are aware of the changes and "are already thinking about how they can be part of the ecosystem once testing shifts out of the big labs and into the physician's office."