Cassandra Fraser and graduate student Guoqing Zhang synthesized a new 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. The new material simplifies the imaging of oxygen-deficient regions of tumors. Such tumors are associated with increased cancer aggressiveness and are particularly difficult to treat.