When it comes to nanosensors for medical diagnostics, gold nanoparticles are often the first choice for enabling early disease detection. This is due to gold nanoparticles’ ability to detect biomarkers at very low concentrations. They undergo intense color changes when in the presence of certain targets.
Just last year, researchers from London Centre for Nanotechnology at Imperial College London used gold nanoparticles and plasmonics to create a biosensor capable of detecting minute amounts of a biomarker.
Now, in research led by Professor Warren Chan of the University of Toronto’s Institute of Biomaterials and Biomedical Engineering (IBBME), gold nanoparticles’ capabilities have been exploited again to create a simple but highly sensitive diagnostic tool for detecting diseases.
The typical design for other gold nanoparticle-based biosensors involves DNA strands being attached to the particles. In these methods, the gold nanoparticles clump together when in the presence of a target gene turning the sample blue.
In contrast, the method developed by the University of Toronto team involves submerging the gold nanoparticles into a DNA-based enzyme (DNA-zyme) solution. When the DNA-zyme and gold nanoparticle solution comes into the presence of the disease gene, the DNA-zyme effectively cuts the DNA from the gold nanoparticles, which turns them a bright red color.
“It’s like a pair of scissors,” said IBBME PhD student Kyryl Zagorovsky in a press release. “The target gene activates the scissors that cut the DNA links holding gold particles together.”
While the London researchers employed the increasingly popular method of plasmonics with their gold nanoparticle biosensor to boost the signal for the sensor, the Canadian team found that their method resulted in a biosensor capable of detecting very low concentrations of DNA without requiring a boost to the signal. In addition to it being very sensitive, the researchers claim that the device can also test for numerous diseases in parallel.
While high-sensitivity and multiple-target capabilities are desirable, the underlying aim was to make sure the device was simple. “There’s been a lot of emphasis in developing simple diagnostics,” said Chan in the release. “The question is, how do you make it simple enough, portable enough?”
The researchers have definitely ticked this box by demonstrating that the testing solution can be made into a powder form so that it can be easily transported and won’t degrade over time. In this powder form the researchers believe that a test could be developed around the technology that would be sold as on over-the-counter test for detecting HIV or malaria.
Chan notes: ““We’ve now put all the pieces together.”
Photo: University of Toronto