Chemical Engineering; Canada Research Chair in Advanced Targeted Delivery Systems

Accurate Diagnosis without Delay:
Testing for Infection using a Lab-on-a-Chip

By Katie Webb, CBB Biographer Frank Gu
January 4, 2013

Current technology provides doctors with two options for the diagnosis of infections. The first of these is the traditional culturing of samples in a laboratory setting, a method that provides accurate results, but at the cost of delaying treatment. The alternative is a single marker test (such as a sample dipped in a solution which changes colour based on the presence of a single type of pathogen) which can provide immediate results and allow treatment to begin in a more timely fashion, but leads to an increased number of false positive and negative diagnoses.

Frank Gu, member of the Centre for Bioengineering and Biotechnology, and his colleagues are working to provide a viable alternative. Using a parallel screening method and lab-on-a-chip technology, Gu is working towards the creation of a test which can simultaneously and almost instantaneously distinguish between different types of fungal, yeast, and bacterial infections. This type of test uses a single sample to examine the presence of multiple types infections, based on the emergence of a pattern of molecules. It does so by examining the concentration of a number of different types of biomarkers within a single sample placed in a lab-on-a-chip and immediately providing an output that tells the test provider which biomarkers are present and absent. This in turn will allow physicians to determine, based on the specific pattern of present biomarkers, what type infection a patient has.

The key, Gu says, is determining which biomarkers (individually and in combination) are the most relevant indicators of each type of infection, and at what threshold (or concentration) those markers become a relevant to demonstrating a probable infection instead of being part of the normal ecosystem. Collaboration with medical professionals has allowed Gu and his colleagues to effectively investigate these key determinates and begin work on a catalogue of infections based on their distinguishing biomarkers and the thresholds at which these biomarkers demonstrate infection. This in turn, has given them the ability to discriminate between biomarkers that are useful indicators when included for testing and at what threshold they should test positively to indicate presence of infection.

Gu and colleagues have applied this new testing method to the world of optometry in efforts to minimize eye infections in contact lens wearers. Since taking a sample of infected tissue from the eye is invasive and uncomfortable, Gu has created a nanotechnology based sensor that has been used to coat the inside of contact lens cases and, using a simplified output version of the above tests, turns colour signalling the need to change lenses when unhealthy levels of pathogens are found. Using such a technology assists wearers in deciding when contact lenses should be replaced in a way which both optimizes their economy and prevents transmission of infections from contaminated contact lenses.

Gu’s research has capitalized on new developments in nanotechnology to provide a quick and accurate alternative to testing for infection applicable to both home and medical use. His method of parallel screening for multiple contaminates promotes improved quality of care by providing not only a way to visualize the presence of an infection, but by assisting in determining the type of infection and allowing for immediate action.

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University of Waterloo

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