Guoqing Zhang (Grad ’10), a chemistry doctoral student at UVA, was experimenting with a sunscreen compound when he made a startling discovery. As he crushed crystals under an ultraviolet lamp, the green-blue-emitting material suddenly glowed yellow. When smeared on a surface, after a few minutes, the yellow regions reverted to green-blue.

“You’ve got to see this!” he hurried to tell his adviser, chemistry professor Cassandra Fraser. “It’s self-healing,” Fraser observed. “It can be written and rewritten.”

Fraser and Zhang have since created other color combinations and methods for “fixing” the colors for varying lengths of time. They even have a way to create a negative image—a material that turns dark in scratched areas.

Guoqing Zhang and Cassandra Fraser

Fraser and Zhang are working with groups as diverse as visual artists and materials engineers, business partners and high school students to imagine the possibilities for their very visual discovery. They even started a new company, Luminesco, with the idea that these compounds could be used as high-tech “mechanosensors” as well as possibly in forensic and security applications.

In the lab, Fraser and Zhang continue to work toward fabricating light-emitting biomaterials and chemicals for a variety of practical uses. This past year, they also reported a new nanosensor that simplifies the imaging of oxygen-deficient regions of tumors. Cancer researchers are now testing it at UVA and Duke.