Researchers in the chemistry department at the University of Virginia (Charlottesville) and in the radiation oncology department at Duke University Medical Center (Durham, NC) have invented a light-emitting biomaterial that they hope will improve tumor imaging.
The oxygen nanosensor couples a light-emitting dye with a biopolymer, simplifying the imaging of oxygen-deficient regions of tumors, which are associated with heightened cancer aggressiveness and are particularly difficult to treat.
The new material is based on polylactic acid, a biorenewable, biodegradable polymer. Safe for the body and the environment, the material is also easy and inexpensive to fabricate in the form of films, fibers, and nanoparticles. University of Virginia scientists Guoqing Zhang and Cassandra Fraser synthesized the material by combining a corn-based biopolymer with a dye that is both fluorescent and phosphorescent. The phosphorescence appears as a long-lived afterglow that is only evident under low oxygen or oxygen-free conditions.
Zhang devised a method to adjust the relative intensities of short-lived blue fluorescence and long-lived yellow phosphorescence, producing a calibrated colorful glow that allows visualization of minute levels of oxygen. The biomaterial displays oxygen-sensitive phosphorescence at room or body temperature, making it suitable for use in tissues.
Cancer researchers at Duke University realized that the new material could be useful for real-time and extended-time spatial mapping of oxygen levels in tumors. This is important because hypoxia—or insufficient oxygen in tumors—is a major source of resistance to radiation and chemotherapy treatment.
“The method developed here holds great promise for being able to perform measurements of tumor hypoxia cost-effectively,” says study coauthor Mark Dewhirst, a professor of radiation oncology, pathology, and biomedical engineering at Duke. “This kind of tool could greatly increase our knowledge about methods to eliminate tumor hypoxia, which could lead to more effective treatments.”
