The device combines a method of amplifying small samples of the pathogen’s genetic material with a computer chip that rapidly responds to them – offering speedy results for healthcare workers in the developing world.
1. Biological engineer Dan Luo came up with a way method to amplify very small samples of a pathogen’s DNA, RNA, or proteins.
His team assembled DNA into a Y shape. Attached to the base of the Y is an antibody designed to lock onto a pathogen. At the same time, another Y is tagged to lock onto a different part of the pathogen molecule. When the targeted pathogen is present, many double-Ys linked together by a pathogen molecule are formed (pictured).
And, attached to one of the Y’s arms is a molecule that will chain up with other similar molecules when exposed to UV light. This way, double-Ys links to other double-Ys, forming long chains that clump up into larger masses. These chains won’t be created without the presence of the targeted pathogen.
2. Meanwhile, electrical and computer engineer Edwin Kan designed a computer chip that quickly responds to these amplified samples.
The new chip measures both the mass and charge of molecules that fall on it. The large clumps of Y-DNA have a much larger mass and charge than single molecules, triggering the detector. (Accordingly, lower masses and charges indicate the absence of the pathogen.)
The new chip uses CMOS technology, which is compatible with common electronic devices. A detector might, for example, be controlled and powered by a cellphone.
Together as a handheld device, these innovations will report in half an hour what would normally require transporting the sample to a lab and waiting days for results. Just 30 minutes!
The work is supported by the Bill & Melinda Gates Foundation as part of the Grand Challenge program to develop “point-of-care diagnostic.” The foundation distributed $25 million to 12 teams – each working on different aspects of a practical, low-cost testing kit.
Via Cornell University.
Image: Luo Lab