Thermodynamics and Chain Dynamics in Spin-labeled Peptide Block Copolymer Assemblies

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With this award, the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry is funding Professors Daniel A. Savin and Gail E. Fanucci of the Department of Chemistry at University of Florida to explore the self-assembly of spin-labeled, peptide containing block polymers to discover how molecular level structure and interactions can result in global morphology changes. Given the wealth of knowledge that peptide chemists have regarding protein structure, folding, and function, polymer scientists can use this toolbox and apply the same principles to synthetic polymer-polypeptide hybrid systems. From an application standpoint, peptide-based hybrid materials have shown potential as pH sensitive drug delivery vehicles and hydrogels that have advantages in terms ofbiocompatibility. Responsive materials have also been used to produce molecular actuators and switchable surfaces. The training program in the Savin and Fanucci groups integrates teaching and research in a broad range of disciplines including chemistry, physics, biochemistry and polymer science, from K-12 to postdoctoral researchers. Students gain a comprehensive understanding of polymers andbiomaterials in many areas of synthesis, characterization, morphology, spectroscopy, scattering and rheology. This multidisciplinary approach is essential not only from an educational standpoint, but also to produce well-rounded graduates who are attractive to a variety of employers in both academic and industrial settings. The team is committed to broadening participation and strongly encourages research participation by undergraduates. The outreach program continues two highly successful programs by Savin and Fanucci at the K-5 and 9-12 levels, respectively, and adds a new program aimed at mentoring local foster children at the high school level. This research is focused on utilizing site specific spin-labels as probes to characterize the local environment and monitor changes in the self-assembly and morphological transitions in peptide-based block copolymer assemblies. Macroinitiators are prepared that contain the radical spin label agent TEMPO, and aminoethylpiperazine. Copolymers are then synthesized by ring opening of N-carboxyanhydrides of amino acids. Spectroscopic tools such as electron paramagnetic resonance and Overhauser dynamic nuclear polarization NMR spectroscopy are used to provide local interrogation of end-to-end distributions, hydration, accessibility, and segmental dynamics in responsive block copolymer assemblies. This characterization is coupled with morphology characterization where light scattering and electron microscopy are used to determine critical parameters such as size, shape, aggregation number, and the average chain density at the interface of the assemblies. Results associated with this research could enable the establishment of a new analytical platform to determine local conformational, thermodynamic, and dynamic properties of polymers in assemblies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.