The beacons, created by researchers from Rice University's Center for Biological and Environmental Nanotechnology, are activated by proteases, whose expression is altered in such illnesses.
"The idea is to develop a 'smart' nanostructure that is dark in its original state but lights up very brightly in the presence of enzymatic activity associated with a particular disease process," says study lead author Jennifer West. "Other groups have used targeted nanostructures including quantum dots for molecular imaging, but they have never been able to adequately solve the problem of clearly distinguishing between the 'cancer is here' signal and the background light which arises from nanostructures not specifically bound to their molecular targets."
The new beacons use quantum dots, which give off light in the near-infrared spectrum. Gold nanoparticles are tethered to the quantum dots to inhibit their luminescence. The tether holds the nanoparticles close enough to prevent the quantum dots from giving off light. The idea is for the tether to be cleaved to expose light in the presence of disease biomarkers.
In their test system, the Rice researchers used a peptide tether that is cleaved by the enzyme collagenase. This dimmed the light by 70% until the nanostructures were exposed to collagenase.
Ultimately, the researchers hope to pair a series of quantum dots to an index of linker proteases.
The research is reported in the journal Biochemical and Biophysical Research Communications.