Presidential Young Investigator Award

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This research involves exploiting the biodegradability, chirality, and spatial order of biopolymers for the construction of important new materials. The bacterial polyesters, cellulose, and lysozyme have been selected for this work. Poly(hydroxybutyrate-co-hydroxyvalerate), PHBV, derived from bacterial fermentation is being used to obtain materials which have identical compositions but differ in the crystalline lattice structure, crystalline perfection, spherulite size, and percent crystallinity. Synthetic analogues of bacterial polyesters are being synthesized by carrying out a ring-opening polymerization of enantiomerically pure n-alkyl lactones. PHBV is being blended with other polymers to develop different morphologies. The microbial degradability of these samples will then be studied using variable biological environments. In this way, fundamental relationships between polymer structure, morphology, and degradability will be established. Cellulose derivatives will be used to form liquid crystalline polymeric materials where the cholesteric pitch will be highly sensitive to external signals. By synthesizing cellulose derivatives which have photo- and electroresponsive groups attached at controlled sites along the chain, relationships between polymer design, the aplied external signal, and the optical rotatory properties of the material will be established. This concept will be extended to other chiral biopolymer based systems to explore the effects of chain dynamics on response time. The insertion of photo- and electroresponsive groups at selective sites of the protein lysozyme will be used to initiate research into the modulation of enzyme conformation, and therefore activity. The goal of this work is to explore methods which allow enzymes to essentially be turned on and off in response to external signals which alter the spatial arrangements at protein catalytic sites. These proteins may provide novel routes for the transmission of light and electrical signals.