Browsing by Author "Fabich, H. T."
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Item Magnetic resonance analysis of capillary formation reaction front dynamics in alginate gels(2011-09) Maneval, James E.; Bernin, D.; Fabich, H. T.; Seymour, Joseph D.; Codd, Sarah L.The formation of heterogeneous structures in biopolymer gels is of current interest for biomedical applications and is of fundamental interest to understanding the molecular level origins of structures generated from disordered solutions by reactions. The cation-mediated physical gelation of alginate by calcium and copper is analyzed using magnetic resonance measurements of spatially resolved molecular dynamics during gel front propagation. Relaxation time and pulse-field gradient methods are applied to determine the impact of ion front motion on molecular translational dynamics. The formation of capillaries in alginate copper gels is correlated to changes in translational dynamics.Item Microbial and algal alginate gelation characterized by magnetic resonance(2012-10) Fabich, H. T.; Vogt, Sarah J.; Sherick, Matthew L.; Seymour, Joseph D.; Brown, Jennifer R.; Franklin, Michael J.; Codd, Sarah L.Advanced magnetic resonance (MR) relaxation and diffusion correlation measurements and imaging provide a means to non-invasively monitor gelation for biotechnology applications. In this study, MR is used to characterize physical gelation of three alginates with distinct chemical structures; an algal alginate, which is not O-acetylated but contains poly guluronate (G) blocks, bacterial alginate from Pseudomonas aeruginosa, which does not have poly-G blocks, but is O-acetylated at the C2 and/or C3 of the mannuronate residues, and alginate from a P. aeruginosa mutant that lacks O-acetyl groups. The MR data indicate that diffusion-reaction front gelation with Ca2+ ions generates gels of different bulk homogeneities dependent on the alginate structure. Shorter spin–spin T2 magnetic relaxation times in the alginate gels that lack O-acetyl groups indicate stronger molecular interaction between the water and biopolymer. The data characterize gel differences over a hierarchy of scales from molecular to system size.