Team:Washington/Design

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Design of Paper Platform for Yeast Biosensors

After learning about the problems that Washington State faces in regards to marine biotoxins and the enormous cost of performing toxin screening in the local shellfish industry, we wanted to develop a paper-based biosensor for detecting small molecules, which could later be applied to detecting shellfish toxins. To do this, we first decided to develop a paper platform to house biosensing yeast.

After talking with experts in the shellfish industry (as described in our Integrated Human Practices page), we developed a set of criteria that our device should meet. First, the device should be small and portable (no larger than 4cm by 5cm) so that it could be used as a point-of-care diagnostic test. Secondly, it should be cheap and easy to manufacture (no more than $5 per test strip), without complex machinery or inaccessible materials. Third, it must have a barrier that protects the yeast from the non-sterile outside conditions, while containing the yeast to prevent spread of genetically engineered organisms into the environment. Lastly, it must be fast (less than three hours), as traditional lab-based detection methods often take 24 to 48 hours. While the testing time is a property of the biological detection pathway, the other conditions can be met by the paper device itself.

We constructed the device by cutting strips of heavy-duty filter paper and taping a 1mm sheet of PDMS polymer to either side to act as the yeast containment area. This basic device was then autoclaved to ensure sterility, and media and biosensing cells were added to the yeast containment area. A target molecule in solution could then travel up the paper to reach the yeast. After testing our device with a cell lysis assay and our theophylline detection pathway, we can clearly show that our device is functional.

This platform is both simple and generalizable, and could be functionalized with a wide variety of yeast biosensors. Such technology, if developed into a commercial product, could therefore have a significant impact on industry, making detection of toxins, pathogens, environmental contaminants, heavy metals, and other molecules much easier and more affordable.

With any disposable device, many environmental concerns should be taken into account. It is important that engineered yeast are not able to grow in the environment after a consumer has disposed of the device housing them. Thus, any yeast biosensor in our finished product should have a biological killswitch. Additionally, as we develop our device, we hope to integrate biodegradable materials to cut down on waste.

Demonstration of a Functional Prototype

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