PhD student Kyryl Zagorovsky and Professor Warren Chan of the University of Toronto’s Institute of Biomaterials and Biomedical Engineering (IBBME) have created a rapid diagnostic biosensor according to a Feb. 28, 2013 news item on phys.org,
A diagnostic “cocktail” containing a single drop of blood, a dribble of water, and a dose of DNA powder with gold particles could mean rapid diagnosis and treatment of the world’s leading diseases in the near future. …
The recent winner of the NSERC E.W.R. Steacie Memorial Fellowship, Professor Chan and his lab study nanoparticles: in particular, the use of gold particles in sizes so small that they are measured in the nanoscale. Chan and his group are working on custom-designing nanoparticles to target and illuminate cancer cells and tumours, with the potential of one day being able to deliver drugs to cancer cells.
But it’s a study recently published in Angewandte Chemie that’s raising some interesting questions about the future of this relatively new frontier of science.
Zagorovsky’s rapid diagnostic biosensor will allow technicians to test for multiple diseases at one time with one small sample, and with high accuracy and sensitivity. The biosensor relies upon gold particles in much the same vein as your average pregnancy test. With a pregnancy test, gold particles turn the test window red because the particles are linked with an antigen that detects a certain hormone in the urine of a pregnant woman.
(Until now, I’d never thought about how a pregnancy test actually works and always assumed it was similar to a litmus paper test of acid.) The University of Toronto’s Feb. 28, 2013 news release, which originated the news item, describes the technology in more detail,
Currently, scientists can target a particular disease by linking gold particles with DNA strands. When a sample containing the disease gene (e.g., Malaria) is present, it clumps the gold particles, turning the sample blue.
Rather than clumping the particles together, Zagorovsky immerses the gold particles in a DNA-based enzyme solution (DNA-zyme) that, when the disease gene is introduced, ‘snip’ the DNA from the gold particles, turning the sample red.
“It’s like a pair of scissors,” said Zagorovsky. “The target gene activates the scissors that cut the DNA links holding gold particles together.”
The advantage is that far less of the gene needs to be present for the solution to show noticeable colour changes, amplifying detection. A single DNA-zyme can clip up to 600 ‘links’ between the target genes.
Just a single drop from a biological sample such as saliva or blood can potentially be tested in parallel, so that multiple diseases can be tested in one sitting.
But the team has also demonstrated that [it] can transform the testing solution into a powder, making it light and far easier to ship than solutions, which degrade over time. Powder can be stored for years at a time, and offers hope that the technology can be developed into efficient, cheap, over-the-counter tests for diseases such as HIV and malaria for developing countries, where access to portable diagnostics is a necessity. [emphases mine]
I think the fact that the testing solution can be made into powder is exciting news. Medical technologies can be wonderful but if they require special handling and training (e.g., a standard vaccine is in a solution which needs to be refrigerated [that's expensive in some parts of the world] and someone who is specially trained has to administer the injection) then they’re confined to the few who have access and can afford it.
Here’s a citation and a link to the researchers’ paper,
A Plasmonic DNAzyme Strategy for Point-of-Care Genetic Detection of Infectious Pathogens by Kyryl Zagorovsky, and Dr. Warren C. W. Chan. Angewandte Chemie International Edition DOI: 10.1002/anie.201208715 Article first published online: 10 FEB 2013
Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
This article is behind a paywall.
ETA Mar. 1, 2013 10:42 am PST: I made a quick change to the title. Hopefully this one makes more sense than the first one did.