Developing New Soft-Bonded Light-Reversible Polymer Bio-Materials

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The long-term objective of this proposed research program is the development of new bio-inspired and bio-sourced polymer materials that are self-assembled non-covalently from aqueous solution to form stable bio-films and structures, and that also respond to mild stimuli (such as light) to effect local reversible structural transitions. An overarching goal lies in understanding how these photo-reversible bio-materials interact at real biological interfaces, and then exploring the extent of control one can gain over this interface for a variety of bio-medical or bio-engineering applications. These new polymer assemblies will mimic real biological tissue in their soft, wet, compliant tune-ability, and the light-responsive shape-changing azo dyes incorporated in small amounts mimic our rhodopsin/retinal systems that enable vision, to provide a direct opto-bio communication interface. From a practical standpoint these new polymers are of interest as smart' surfaces for signaling, sensing, and controlling adjacent biological activity, due to the combination of mild visible photochemical functionalities, and their inherent soft, wet bio-compatibility. From the standpoint of fundamental science, these new materials and their study ideally will enable us to contribute to basic understanding of biological function at the interface between living tissue/cells and artificial media, and communication between them, from a chemical and materials perspective. Built from water-soluble and bio-sourced components, when self-assembled together these new materials can form insoluble, stable, and strong polymeric materials. This controlled solubility transition to stability permits promising natural polymers to be incorporated for the first time (silk and other proteins, chitosan and other polysaccharides), to retain their desired properties yet prevent their ready solubility in water, and thus be applied as improved cell culture media, and eventually in vivo as biocompatible coatings for implants. This proposal represents the first expansion of our research from more simple artificial mimics of bio-polymers, into real bio-sourced superior natural polymers. This will enable us to develop entirely natural (ie: FDA-approved, even edible) polymeric assemblies for in vivo biomedical applications, that are completely soft-bonded together, to thus retain their biocompatibility and low toxicity. This could further allow soft-bound chemical cargo for delivery to be readily and gently loaded and released. The long-term vision of this research program lies in the development of new bio-inspired and bio-mimetic materials that can be self-assembled from aqueous solution and respond to light, understanding how they interact with real biological interfaces, and then exploring the extent of control over this interface for biomedical applications, now using nature as the inspiration for both the soft organic materials, and for light as the communication medium.