Investigation of the Effect of Mechanical Strain on the Orientation of Cellulose Microfibrils in the Primary Cell Wall
Open Access
Author:
Sau, Moujhuri
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Dr. Seong Han Kim, Thesis Supervisor Andrew Zydney, Thesis Honors Advisor
Keywords:
Cellulose Primary Cell Wall SFG Sfum Frequency Generation Cellulose Microfibril
Abstract:
The objective of this thesis is to study the reorientation of cellulose microfibrils in the primary cell walls of onions with the application of a mechanical strain. Sum Frequency Generation (SFG) spectroscopy is used for this study because it is non-invasive and non-destructive, gives information about cellulose microfibril packing over the bulk of the cell wall, and is non-centrosymmetric and therefore specific to bonds in the cellulose crystal. An artificial stress of 20g (196 mN) is applied to the onion epidermis for 17 minutes to stretch the cells in both the longitudinal and transverse directions to the long axis of the cell. It is found that after the mechanical stretch in the longitudinal direction, the cellulose microfibrils significantly change their orientation, possibly along the direction perpendicular to the direction of the stretch. After mechanical stretch in the transverse direction, the cellulose microfibrils show a more slight change, opposite in direction to the change in the longitudinal direction. These results show that mechanical stress changes the orientation of cellulose microfibrils in the primary cell wall significantly, and can be used as a model to study changes in the cell wall during cell growth.
