Imagine a test that could tell you instantly whether or not you had a case of strep throat, or just a bad cold. No doctors. No waiting. No hassle.
That’s the idea behind research from UT Austin’s Ellington Lab, published in the journal Nature Nanotechnology. The so-called “DNA walker” developed by Cheulhee Jung, Peter Allen and Andrew Ellington isn’t the first ever created – DNA walkers are fairly common in nanotechnology – but its mechanics are different than any other ever devised.
Typical walkers have a linear progression, but the Ellington Lab walker meanders and uses a method that recycles its catalyst – meaning that it can self-assemble its pathway, navigate a particle in any direction and mark corresponding areas that share a structure with its catalyst. Previously developed walkers typically have single, precisely-planned tracks, like a train.
“Ours is more like a fur ball, where you have a larger ball displaying thousands of strands of DNA, this carpet of DNA is what our walker walks on,” says study co-author Peter Allen. “It is a little more random than a locomotive, but it has a pretty clear inclination to stay on that surface and do its little walking job.”
Allen, who now a professor of chemistry at the University of Idaho, says that with each step in that little walking job, a walker tags strands of DNA that match its catalyst with a fluorescent dye. The walker takes around 35 steps per walkabout, though Allen says that number’s likely to grow as the research becomes more robust.
The walker research has long-term benefits for preventative healthcare – like tagging cancerous cells – but Allen also sees a more practical application in diagnosing maladies.
“It takes a somewhat sophisticated process right now to get some information after that, but if we could encode the intelligence of that test into the DNA that builds this walker system, we could make it much easier for a person to read it as opposed to a trained lab scientist who would have to run numerous steps," Allen says.
Allen and the Ellington Lab envision a “dipstick” test similar to a pregnancy test.
A patient provides a sample for, say, strep. That sample would then provide the catalyst for a walker, which would contain a protocol to mark only strep-infected areas. All of this would be interpreted by the internal circuit and, ideally, could deliver an easily interpreted readout like a pregnancy test. That application, Allen says, is much closer to fruition.
“People are interested in using DNA origami and DNA nanomachines to build more sophisticated systems for drug delivery,” Allen says. “And I think that’s really interesting for a sort of first-stage prototype of something that may well be really important in 10 or 20 years. But I think the near-term applications are all going to be diagnostic."
