Using light to diagnose the presence of viruses or other invaders in the body isn’t new. Typically, the tests use a probe molecule that locks onto a gene known to belong to the villain. The combination of the two changes the frequency of light emitted by the target, and the change can be seen and quantified by an optical microscope.
However, the tests can be cumbersome and time-consuming: usually, the target gene has to be replicated into a batch big enough to show a detectable signal. That’s expensive and takes time.
To avoid all that, researchers at Stanford University created a method that sets up rows of silicon squares measuring a few hundred nanometers on a side. A nanometer is one billionth of a meter.
The group affixed strands of assorted DNA to the tops of the blocks, immersed the array in a neutral solution, then laid a different probe atop each block. The probes grabbed onto their respective targets when the target strands of DNA passed by.
The connection shifted the light frequency emitted by each target strand, allowing the microscope to “see” the shift and affirm the presence of a particular kind of tissue.
Importantly, the method can reveal the amount of target DNA the probes find, giving doctors a clue about how much of the offender is present in the body.
In theory, an array of the nanoboxes could scan for more than 10,000 separate conditions within a few minutes, once they’re seeded with the right markers, the developers said.
In addition, the tiny squares could have uses outside of medicine, such as detecting the presence of specific strains of algae in polluted waters.
The developers have organized a for-profit company to commercialize their discovery.
TRENDPOST: Because the nanoboxes can do their detecting outside the body, clinical trials aren’t needed to bring the method into clinical or other scientific uses, which should happen within four years.
Stanford University’s silicon wafers that can snag and signal the presence of DNA from specific organisms.
Photo: Stanford University