Cassandra FraserCassandra Fraser directs the Transduction Project, working with many collaborators across Grounds and beyond. Disciplinary transduction, exploring ideas from many angles, is a longstanding practice and passion of hers in research, teaching and creative pursuits. Over the years she has run programs on Color, Biomaterials, Designing Matter, Metals in Medicine and the Environment, and Plastic/ity. Material, sustainability, health and design themes figure prominently. A brief online CV including links to interdisciplinary projects may be found here.

Cassandra is a Professor of Chemistry, with joint appointments in Biomedical Engineering and the School of Architecture. Before moving to Charlottesville in 1995, she conducted postdoctoral research in catalysis and bio-inspired and degradable polymers at Caltech. For her Ph.D. research at The University of Chicago, crossing organic and inorganic chemistry, she synthesized chiral bimetallic catalysts inspired by enzymes that activate and deliver oxygen in natural systems. Prior to graduate study in Chemistry, she studied religions and culture at Harvard Divinity School, earning a Master of Theological Studies degree. While in Cambridge, she worked in the Schlesinger Library on the History of Women in America, for Boston Aging Concerns, and conducted cancer research in the Laboratory of Toxicology and Department of Cellular and Developmental Biology at Harvard. Before that, she studied chemistry, art and the history of thought at Kalamazoo College. For her senior thesis on the History of Women in the Society of Friends, she conducted research at the Haverford College Quaker Collection.

Research in the Fraser laboratory at the University of Virginia is concerned with responsive materials.  Early work involved the design, synthesis, and characterization of polymeric metal complexes, metal-centered linear and star shaped polymers inspired by metalloproteins in nature. Current work is focused on luminescent boron dyes. Learn more about the Fraser Lab here.

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Boron Dyes in Solution

As solid pigments, boron dyes serve as mechanosensors. They display rare reversible mechanochromic luminescence. They change emission color when scratched or smeared but can revert back to their original color over time. In essence, they are renewable inks. Dye coated surfaces can be written on and erased many times. This is an example of mechanical > optical signal transduction. The solid state dye serves as the interactive medium. Humans have interfaced with this process in multiple ways, first in synthesizing these dyes, discovering this rare phenomenon, then characterizing and further exploring it. Likewise, the optical effects are activated when forces are applied. This can be achieved in various ways, for example, with writing, smearing, scratching or crushing. These dyes have also mediated disciplinary transduction, inspiring art folio projects, interactive design exhibits, and sound art productions. Learn more about BF2AVB, a Scratch the Surface Ink, through exhibit documentation here. Other projects are described on the Fraser Lab News page.

Mechanochromic Luminescence:  Scratched orange regions fade to blue over time.

While dye effects are activated by human intention, it is also important to note that signals also flow in the opposite direction, from the dye to humans. The optical effects are colorful, sometimes transitory–a delight to the eye. Furthermore, it was when a scientist smeared a boron dye between his fingers, curious to know if it felt greasy, that the discovery of mechanochromic luminescence was made. Then, and in fingerprint detection, another interesting use of these materials, the dye can come in direct contact with the skin. Though no toxicity has been observed (some components of the dyes even appear in sunscreens), it is important to note that these compounds and most others in the world around us have not been tested for their effects on human health and the environment.  Green chemists and concerned citizens urge otherwise.

The boron dyes also serve as optical oxygen sensors.  When embedded in a biocompatible, biodegradable polymer called poly(lactic acid) or PLA or other suitable matrices, the boron dyes exhibit another rare phenomenon, both fluorescence and rare room temperature phosphorescence. This two-color effect has been harnessed for sensing, given that the phosphorescence afterglow is sensitive to oxygen. The presence of oxygen modulates the color and intensity of light emission that is observed. This an example of chemical > optical signal transduction. Here the interactive medium is the dye-polymer material, though when administered to cells, tissues or in vivo, the entire material/biological system might be thought of as the medium through which light and oxygen move. Particularly at the molecular level, the boundaries between one material and the other can become blurred. Here too, the human interface is captured by the scientist as designer, investigator, and inventor of new technologies and the materials display compelling visual effects, emitting photons that are detected by receptors in the eye. In collaborative biomedical research, oxygen nanosensors are administered to cells, tissues and organisms, in cancer, epilepsy, brain, wound, and tissue engineering studies and more. One day these materials could find use in human medicine.

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Writing with a Nitrogen Pen: Yellow phosphorescence lights up in oxygen-free zones surrounded by background blue-green fluorescence.

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Tumor Hypoxia Imaging.  Red: oxygen rich vasculature. Blue: oxygen poor tumor.

Future research goals focus on Real World Chemistry, investigating material pathways and global systems chemistry, with an emphasis on environmental, health and societal impacts. Incorporating findings into science education and communicating to broader audiences through digital storytelling and visual media will figure prominently. Ongoing experimentation with interdisciplinary ways of working that integrate research, teaching, service and creative work, and take advantage of WallSpace, a new interspace at UVA, is also envisioned.

Teaching activities in the Chemistry Department have also included organic, inorganic, and materials chemistry courses, often with biomedical and green themes. Cassandra has been fortunate to work with outstanding students over the years.

Other Interests include writing, photography, correspondence, news, hiking, travel, spaces, lived religions/spiritual practices, and cultural exchange. Random observations of material structures and processes and encounters with people, plants and animals are ongoing fascinations, whether accidental or by design.

More Information

Story of Stuff.  The animations on this site are a good introduction to environmental, health and societal impacts of our choices regarding material uses and flows.

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