Advanced X-ray Scattering of Plant Cell Walls
Restricted (Penn State Only)
- Author:
- Del Mundo, Joshua
- Graduate Program:
- Chemical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 07, 2023
- Committee Members:
- Robert Rioux, Professor in Charge/Director of Graduate Studies
Enrique Gomez, Co-Chair & Dissertation Advisor
Esther Gomez, Co-Chair & Dissertation Advisor
Bryan Vogt, Major Field Member
Seong Kim, Major Field Member
Daniel Cosgrove, Outside Unit & Field Member - Keywords:
- cell wall
cellulose
XRD
SAXS
WAXS
GIWAXS
primary cell wall
secondary cell wall
pectin
lignin
xylan
xyloglucan
RSoXS
NEXAFS
plant cell wall
lignocellulose
synchrotron
mechanics
hydration - Abstract:
- Structural characterization of plant cell walls is the basis for the development of new plant-derived biomaterials and sustainable energy. In this dissertation, we utilize emerging synchrotron X-ray scattering technologies and new sample preparation methods to understand plant cell wall microstructure and polymer interactions. Grazing-incidence wide-angle X-ray scattering (GIWAXS) enhances signal-to-noise of hydrated primary cell wall, revealing changes in cellulose crystal and pectin organization upon dehydration. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), in conjunction with other techniques, of onion epidermal cell wall at increasing strain reveals reorganization and realignment of cellulose microfibrils towards the direction of the stretch as well as deformation of cellulose crystals. SAXS and WAXS of secondary cell wall mutants of Arabidopsis thaliana support that xylan interactions are critical for normal cellulose structure in secondary cell walls, while lignin interactions are less influential on cellulose organization. Finally, we demonstrate that resonant soft X-ray scattering (RSoXS) around the carbon edge can tune the scattering contrast between cellulose and lignin in secondary cell wall, which is low in SAXS. These findings shed light on some uncertainties plant cell wall microstructure, with the motivation of the optimization of plant biomass as a renewable feedstock in many industries.