A new material that couples a light-emitting dye with a biopolymer has been shown to simplify the imaging of oxygen-deficient regions of tumors, which are associated with increased cancer aggressiveness and are particularly difficult to treat. The light-emitting material serves as an oxygen nanosensor, representing a class of new research tools that may also be used to diagnose and detect diseases and to plan treatment strategies. Chemists at the University of Virginia developed the technology and collaborated with cancer researchers at the UVA Cancer Center and Duke University Medical Center to determine possible applications. The material, which combines “green” chemistry with nanotechnology, is based on poly(lactic acid) — a biorenewable, biodegradable polymer that is safe for the body and environment. It’s also easy and inexpensive to fabricate in many forms, including films, fibers, and nanoparticles. The material is useful for medical research as well as environmental research, sustainable design, and green products, say its developers. Guoqing Zhang, a UVA chemistry doctoral candidate, and Cassandra Fraser, a UVA chemistry professor, 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, ultimately creating a calibrated, colorful glow that allows visualization of even minute levels of oxygen. The biomaterial displays its oxygen-sensitive phosphorescence at room or body temperature, making it ideal for use in tissues. The technology is described online in Nature Materials.

The material is being used in preclinical studies to gain insight into cancer biology and treatment response, which could be useful for drug development and testing. Eventually the material could be used as an injectable nanosensor, potentially providing continual data on oxygen levels, biological processes, and therapy responsiveness. “The method developed here holds great promise for being able to perform measurements of tumor hypoxia cost-effectively,” says study co-author Mark Dewhirst, a professor of radiation oncology, pathology, and biomedical engineering at Duke.

Source: Laser Focus World

Posted August 26th, 2009 under Tech Transfer

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