Solution-state 2D NMR of Ball-milled Plant Cell Wall Gels in DMSO-d6

Although finely divided ball-milled whole cell walls do not completely dissolve in dimethylsulfoxide (DMSO), they readily swell producing a gel. Solution-state two-dimensional (2D) nuclear magnetic resonance (NMR) of this gel, produced directly in the NMR tube, provides an interpretable structural fingerprint of the polysaccharide and lignin components of the wall without actual solubilization, and without structural modification beyond that inflicted by the ball milling and ultrasonication steps. Since the cellulose is highly crystalline and difficult to swell, the componentmay be under-represented in the spectra. The method however provides a more rapid method for comparative structural evaluation of plant cell walls than is currently available. With the new potential for chemometric analysis using the 2D NMR fingerprint, this method may find application as a secondary screen for selecting biomass lines and for optimizing biomass processing and conversion efficiencies.