61. Bacterial Cellulose Fibers

The production of cellulose by Acetobacter xylinum was reported by A.J. Brown as early as 1886. From that time, bacterial cellulose (BC) has been used for biomedical, environment, agriculture, electronic, food, and industrial applications [98Las, 14Moh]. Unlike most other sources of cellulose, BC does not contain lignin or hemicelluloses, making it ideally suited for various applications. In terms of structure, BC is composed of fibrils that have a width of about 1.5 nm and these fibrils are crystallized into microfibrils. BC has a relatively high level of crystallinity (60 %) and the degree of polymerization that can be as high as 16,000–20,000. Young’s modulus of a bacterial cellulose fibril has been reported to be in the range of 15–35 GPa and tensile strength between 200 and 300 MPa. However, other researchers have reported the modulus of a single bacterial cellulose fibril to be as high as 114 GPa, compared to a theoretical cellulose crystal modulus of 160 GPa. In addition to these features, BC has a water holding capacity of up to 100 times it weight and a linear thermal coefficient of expansion of only 0.1 × 10⁻⁶ k⁻¹. Typical uses of bacterial cellulose have been as wound dressing. Bioprocess, Xcell, and Biofill are some of the products made from bacterial cellulose that are currently available on the market for wound healing [06Cza, 90Fon]. Other commercial scale applications of bacterial cellulose are in cosmetics, food, and electronics to some extent. The remarkably high wet tensile strength, biocompatibility, high porosity, and ability to be easily formed into various structures are considered to be some of the advantages of using bacterial cellulose for medical applications.