NMR studies of RGD-functionalized hydrogels

PMSE 190

Charles V. Rice, rice@ou.edu, Shawn M. Carter, scarter@ou.edu, and Kevin J. Meyer, kmeyer@ou.edu. Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Room 208, Norman, OK 73019
Using High-Resolution Magic-Angle-Spinning (HRMAS) NMR spectroscopy, the LCST of a NiPAAm hydrogel was found to involve a two-stage process, in which the enthalpy, entropy, and Gibbs free energy were positive values, and significantly greater in the second stage. (Rice, C. V. Biomacromolecules 2006, 7, 2923) The values are dramatically lowered upon the addition of salts (150 mM NaCl and 150 mM CaCl2). The addition of hydrophilic acrylic acid in the polymer backbone at 1, 2.5, and 5% raises the phase transition temperature. When RGDC is added to an acrylamide hydrogel at 2.5%, we are able to make spectral assignments with the standard suite of NMR pulse sequences. These data will be used to evaluate changes in structure and dynamics as a function of percent incorporation, pH, and salt concentration.