Advisory Committee Chair
Alan W Eberhardt
Advisory Committee Members
Joel Berry
Jack E Lemons
Document Type
Thesis
Date of Award
2012
Degree Name by School
Master of Science in Biomedical Engineering (MSBME) School of Engineering
Abstract
Bacterial nanocellulose (BNC) is a biopolymer that has been used in a variety of applications ranging from speaker diaphragms to biomedical products. Created by micro-organisms like Gluconacetobacter xylinus, BNC is composed of long cellulose fibers in a highly crystalline hydrogel. Recent interest in BNC based materials has led to the discov-ery of several cultivation and post-processing treatments that have enabled researchers to control the mechanical and structural properties of the hydrogel. Three BNC treatments were mechanically evaluated through tensile testing. Ten-sile tests were conducted using dogbone shape test strips and a video extensometer. Phys-ical compression of a BNC hydrogels not only removes water from the gel but also in-duces hydrogen bonding between cellulose fibers. Results showed that both the ultimate strength of material and the effective modulus were significantly higher in samples with increased cellulose content (p < 0.01), reaching modulus values up to 260 MPa. Unlike the physical compression method, freeze-drying BNC samples can effectively remove water content without damaging or collapsing the cellulose network. Freeze-dried and rehydrated samples showed no difference with effective modulus when compared to samples of identical cellulose percentage (p < 0.001). The implications of freeze-drying are beneficial during shipment of BNC materials, as they can be dehydrated and pack-aged then later rehydrated without loss of mechanical characteristics. Culture media components were also evaluated. A vitamin solution was used in different concentrations to determine its effects on cellulose production and the resulting mechanical strength of the hydrogel. Results showed that a concentrated vitamin solution not only produced thinner pellicles (p < 0.001), but also produced hydrogels with half the ultimate strength of gels made from a diluted vitamin solution (p < 0.01). While these tests have only eval-uated three of the increasing number of BNC treatments, they emphasize the important of mechanical testing during the development of BNC based biomaterials.
Recommended Citation
Schwertz, Joseph Mathias, "Mechanical Analysis of Bacterial Nanocellulose for Biomedical Applications" (2012). All ETDs from UAB. 2928.
https://digitalcommons.library.uab.edu/etd-collection/2928
