U.S.-Japan Cooperative Ressearch: Fluorescence and Scattering Studies of Polyelectrolytes-Colloid Systems

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9315326 Dubin This award supports a two-year cooperative research project between Professor Paul Dubin, Department of Chemistry, Indiana University- Purdue University at Indianapolis, and Professor Mikiharu Kamachi, Department of Macromolecular Science, Osaka University, and Professor Yotaro Morishima, Department of Macromolecular Science, Osaka University. The joint research focuses on the complex formation between polyelectrolytes and oppositely charged colloids of two types: micelles and proteins. In the former case, there is particular interest in the critical conditions for polyelectrolyte binding, inasmuch as this system provides a unique test of theories for polyelectrolyte adsorption. The Osaka group has pioneered the use of dye- labeled polyelectrolytes to probe the electrostatic potential in the vicinity of the polyion, and these will be used to establish and understand the fundamental relationship among colloid surface charge density, polyion charge density and ionic strength at critical binding conditions. The second topic of investigation is polyelectrolyte-protein complexation, an area of considerable potential significance in bio- separations and enzyme immobilization. A key question is the conformation of the protein in the complex. Fluorescence quenching methods refined in Osaka will be used to answer this question. For both this system and the polyelectrolyte-micelle system, transport processes will be explored using dynamic and electrophoretic light scattering in Indianapolis and forced Rayleight scattering and nanosecond fluorescence spectroscopy in Osaka. ***