LAWRENCE — In architecture, a whispering gallery is an arch or vault that projects sound so that a person at one end can hear someone else whispering from the other side.
In science, whispering gallery mode resonators are tiny glass beads that trap laser light and are proven to detect biological clues that indicate diseases in the human body. But tests using the innovative sensors can be complicated and expensive.
Now, with a $340,000 grant from the National Science Foundation, Robert Dunn, professor of chemistry at the University of Kansas, is leading research to simplify tests using whispering gallery mode resonators.
“Early detection of biomarkers has always been a challenge,” Dunn said. “Oftentimes, it takes a lot of extra chemistry to develop a signal that’s detectable. We really wanted a technique that could work without all the extra chemistry involved in labeling things and also be able to detect multiple biomarkers of different types.”
Employing sensitive fluorescent markers, Dunn’s innovation reduces the complexity of microsphere sensors that conventionally have been used to see biomarkers for disease. His “label-free” technique could make tests less complicated, less time-consuming and less expensive. Also, his method allows for easy testing of a range of markers of a disease at once.
“We don’t have to bind labels onto the proteins or the antibodies as is often done,” said the KU researcher. “Our labels are built right onto the sphere. We can specifically tag those spheres with recognition elements like antibodies or complementary RNA. In our approach, we can tag different recognition sites on different-sized spheres. So when we’re doing this as an imaging approach, once we see a sphere light up we can tell by its size what tag we put on it, and it tells us which element we’ve detected.”
Indeed, video of the light-trapping microspheres from Dunn’s laser lab resembles special effects from an avant-garde film. But for Dunn and his collaborators, the visuals hold the potential to save lives.
Dunn is focusing his technique on detection of ovarian cancer, which affects 21,000 women every year in the U.S. and has a high fatality rate.
“The most frustrating aspect is that ovarian cancer remains one of the most treatable cancers if it’s diagnosed early, before the disease has time to spread from the ovaries,” said Dunn.
Eventually, Dunn hopes his research will lead to an easy-to-use test that could be carried out in a doctor’s office during a routine visit, with instant results. A doctor could place a drop of blood on a glass slide containing the microspheres, then place the slide into an inexpensive device that would analyze the blood for signs of ovarian cancer — and a host of other diseases — using a laser no more robust than one in a CD player.
“Since we don’t have to use labels, there’s not a lot of chemistry involved,” Dunn said. “It also uses an optical approach. Optics are pretty easy to miniaturize and make cheaper. A CD player in your computer uses a diode laser that costs 10 or 15 bucks. So one can easily envision this becoming a very small and cheap device once we get all the details worked out.”