Gold nanostars may be all set to change the fields of medical diagnoses and testing for environmental contaminants, say bioengineers at the Duke University .
The researchers have revealed that their proposition is based on a comparison between all the shapes of nanoparticles studied to date, including rods, cones, cubes, and spheres.
They say that any such revolution would depend upon how light reflects off the particles, and nanostars can dramatically enhance the reflected light.
According to them, this increases their potential usefulness as a tracer, label, or contrast agent.
Since the size and shape of the nanostars affect the spectrum of reflected light, the researchers believe that such tiny particles can also be "tuned" to identify particular molecules or chemicals.
"To our knowledge, this is the first report of the development and use of gold nanostars as labels for molecular detection and description of their controlled synthesis with different sizes and shapes" said Chris Khoury, a graduate student in biomedical engineering working in the laboratory of senior researcher Tuan Vo-Dinh, R. Eugene and Susie E. Goodson Distinguished Professor of Biomedical Engineering and director of The Fitzpatrick Institute for Photonics at Duke.
For their study, the researchers used nanostars in conjunction with a phenomena known as surface-enhanced Raman scattering.
When light, usually from a laser, is shined on a sample, the target molecule vibrates and scatters back in its own unique light, often referred to as the Raman scatter. However, this Raman response is extremely weak.
When the target molecule is coupled with a metal nanoparticle or nanostructure, the Raman response is greatly enhanced by the SERS effect, often by more than a million times, Vo-Dinh said.
"We are trying to understand which type of nanostructures will give us the optimal signal so we can use them to monitor trace amounts of pollutants or detect diseases in their earliest stage" Vo-Dinh said.
"This study is the first demonstration that these nanostars can enhance the effect of SERS to produce strong and unique signatures, like 'optical fingerprints,'" the researcher added.
The researchers revealed that they chose gold was chosen for the study because it is a stable metal that does not cause immune system reactions within the body, and unlike silver, it also does not oxidize in samples.
Their study has been published on-line in the Journal of Physical Chemistry.