Bacterial Cellulose for Skin Repair Materials

As is well-known, cellulose is one of the most abundant biodegradable materials in nature and has been the topic of extensive investigations in macromolecular chemistry. It is of great importance to explore renewable natural polymeric materials to solve problems such as population growth, the energy crisis, environment polution, etc. Presently, human beings can produce cellulose by four means. Two of these are by natural synthesis procedures including plant photosynthesis and microbial synthesis. The other two methods are synthetic and enzymatic synthesis from cellobiose fluoride in vitro and the ring-opening polymerization of new carbonyl derivatives such as nitralin. Over the past 30 years, with the development of molecular biology and the application of cell systems in vitro, the mechanism underlying the biosynthesis of cellulose in nature has been extensively explored. Recently, environmental standards have been enhanced for every product and process. Employing new technologies or redesigning products is thus necessary to meet these new environmental standards (El-Saied et al., 2004). Bacterial cellulose (BC, also known as microbial cellulose, MC) is a promising natural polymer synthesized by certain bacteria. Because of its unique structural and mechanical properties as compared to higher plant cellulose, BC is expected to become a commodity material in various fields. The BC fibers have a high aspect ratio with a diameter of 20-100 nm. As a result, BC has a very high surface area per unit mass. This property, combined with its highly hydrophilic nature, results in a very high liquid loading capacity. Morever, biocompatibility makes it an attractive candidate for a wide range of applications in different fields, especially those related to biomedical and biotechnology applications (Dahman, 2009). The fibrous structure of BC consists of a three-dimensional non-woven network of nanofibrils, sharing the same chemical structure as plant cellulose, which is held together by interand intra-fibrilar hydrogen bonding resulting in a never-dry hydrogel state with high strength. The biosynthetic pathways of BC, including those involving enzymes and precursors, have been described (Chawla et al., 2009). These cellulosic materials are particularly attractive because of their relatively low cost and plentiful supply. Thus, BC utilization is responsible for one of the largest material flows in the biosphere and is of interest in relation to the analysis of carbon flux at both local and global scales (Lynd et al., 2002). Plenty of work has been devoted to designing ideal biomedical devices from BC. Such devices are advantageous in terms of their high paper-like reflectivity, flexibility, contrast, and biodegradability (Iguchi et al., 2000, Klemm, 2006). Besides, BC has proven to be a