Type of Document Dissertation Author Spano, Justin URN etd-05182011-112402 Title Solid-State NMR Studies of Polymeric and Biomembranes Degree PhD Department Chemistry Advisory Committee
Advisor Name Title Wi, Sungsool Committee Chair Dorn, Harry C. Committee Member Madsen, Louis A. Committee Member Morris, John R. Committee Member Yee, Gordon T. Committee Member Keywords
- relaxation time
- antimicrobial peptide
- reverse osmosis
- solid-state NMR
Date of Defense 2011-05-04 Availability unrestricted AbstractThe objective of this dissertation is to demonstrate different applications of ssNMR, with particular emphasis on uses in polymeric and biosciences. First, dynamics investigations on two polymers will be discussed: (1) disulfonated poly(arylene ether sulfone)s /poly(ethylene glycol) blends (BPS-20_PEG), which are under development as chlorine-resistant reverse osmosis (RO) membrane alternatives to aromatic polyamide (PA) technology, and (2) poly(arylene ether sulfone)s modified with 1,4-cyclohexyl ring units to improve processability. Simple cross-polarization magic-angle-spinning (CPMAS) experiments compared the chlorine tolerance of BPS-20_PEG and PA. Techniques capable of detecting motional geometries and rates on timescales from nanoseconds to seconds, including relaxation time measurements, were applied. Correlations were established between relaxation time and water permeability for the RO membranes, and between relaxation time and polydispersity in the 1,4- cyclohexyl ring modified polymer.
Next, 31P and 2H static ssNMR experiments evidencing the formation of toroidal pores and thinned bilayers in oriented zwitterionic and anionic phospholipid bilayers, (biomembrane mimetic systems), by the antimicrobial peptides (AMPs) magainin-2 and aurein-3.3, will be mentioned. The toroidal pore geometries induced by magainin-2 were different than those produced by aurien-3.3. The most prominent features were observed in 2H spectra, implying greater interaction of the peptides with hydrophobic lipid acyl chains.
Following this, a new two-dimensional homonuclear dipolar recoupling MAS experiment, capable of correlating long range 13C-13C spin pairs in a uniformly/ extensively 13C-labeled biomolecule, will be introduced. This technique was demonstrated on 13C-labeled versions of Glutamine and Glycine-Alanine-Leucine. Experiments involving the recoupling of all 13C-13C spin pairs, and experiments with selective recoupling using Gaussian or cosine-modulated Gaussian pulses, were demonstrated.
Finally, work using static 1H- 13C CP ssNMR to selectively detect interfacial water around hydrophobic C60 will be recounted. This project exploited the distance limitation of CP, and 1H spin-lattice relaxation times, to separate the influence of bulk and interfacial water on the spectra. Results indicated that the tumbling of interfacial water is slowed by a factor of 105 compared to bulk water, providing it with a solid-like character, and allowing the hydration shell to be stable at temperatures above the freezing point of water.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Spano_Justin_D_2011.pdf 4.69 Mb 00:21:43 00:11:10 00:09:46 00:04:53 00:00:25 Spano_Justin_D_2011_Copyright.pdf 215.32 Kb 00:00:59 00:00:30 00:00:26 00:00:13 00:00:01
If you have questions or technical problems, please Contact DLA.