July 8, 2009 — When University of Virginia chemistry professor Cassandra Fraser and her research team crossed a light-emitting dye with a corn-based polymer, they discovered a material with some very unusual properties.
The biomaterial developed in Fraser's lab not only has bright fluorescence when exposed to ultraviolet light, but afterwards it also has vivid phosphorescence – a green afterglow – when in an oxygen-free or very low-oxygen environment.
The material exhibits this oxygen-sensitive phosphorescence at room temperature and even at body temperature. It is biodegradable and it senses even extremely low levels of oxygen, which makes it particularly useful.
"Many materials can sense oxygen, but they aren't as well-suited to sense oxygen at very low levels," explains Fraser.
Convinced that this material could have important biomedical applications, Fraser partnered with Richard Price, an associate professor of biomedical engineering at U.Va., to conduct some exploratory research. Encouraging preliminary results helped Fraser and Price obtain $30,000 in seed funding from U.Va.'s nanoSTAR Institute for further investigation.
Low levels of oxygen in the body – called "hypoxia" – can lead to tissue damage and cell death and have been linked to cardiovascular disease, stroke, cancer and diabetes.
"The crux of it all is that cells need oxygen to survive," Price said.
When oxygenation levels fall, cells can respond by dilating blood vessels or even growing new blood vessels. Price's lab is particularly interested in finding out how hypoxia can lead to new blood vessel growth.
"Cassandra's material has the potential to tell us, in very exquisite detail, a lot of things about tissue oxygenation that we didn't necessarily know before," Price said.
With Fraser's material and Price's expertise in vascular models, the pair is attempting in vivo imaging of the features of the vascular system. By injecting nanoparticles of Fraser's material into a live mouse model and obstructing the flow of oxygen in particular areas, Price hopes to obtain very precise measurements about the way that oxygen depletion affects surrounding tissue and stimulates new blood vessel growth.
Fraser notes that their results have impressed a number of other investigators and are opening up promising new lines of research in cancer, cardiology, diabetes and tissue engineering areas.
"The nanoSTAR seed grant and the chance to put these ideas together has really catalyzed not only our project, but other projects too," Fraser said. "If all goes really well, we'll have NIH grants in all these different areas, with teams of people at U.Va. and outside collaborators."