Microfoams of Biopolymers By Laser-induced Stretching : Mechanisms and Applications

Biopolymers are polymers produced by living organisms. Cellulose, starch, chitin, proteins, peptides, DNA and RNA are all examples of biopolymers. This book comprehensively reviews and compiles information on biopolymers in 30 chapters. The book covers occurrence, synthesis, isolation and production, properties and applications, modification, and the relevant analysis methods to reveal the structures and properties of some biopolymers. This book will hopefully be of help to many scientists, physicians, pharmacists, engineers and other experts in a variety of disciplines, both academic and industrial. It may not only support research and development, but be suitable for teaching as well. Microbial cellulose has proven to be a remarkably versatile biomaterial and can be used in a wide variety of fields, to produce for instance paper products, electronics, acoustics, and biomedical devices. Various biodegradable and biocompatible polymeric materials have recently been investigated to fabricate inorganic-organic hybrid composites by mimicking the mineralization system of natural bone, with some successful outcomes. However, the search for an ideal biomaterial with properties and functionalities similar to natural bone is a continuing process because no single material can satisfy all the requirements for creating optimal scaffolding properties, such as strength, toughness, osteoconductivity, osteoinductivity, controlled degradation, inflammatory response, and deformability. In this study, the ultrafine 3-D BC network structure with its native unique properties is exploited for the synthesis of materials analogous to natural bone. Our study showed that the formation of apatite is dependent on the presence and type of surface functional groups in the microfibrillar BC network. Degradation of BC has not been fully evaluated in in vitro and in vivo settings. Other cellulose-based materials have however shown limited degradation. Although the complete degradability of materials for tissue engineering applications is very attractive, it is difficult to practically optimize and synchronize the degradation time and mechanical properties of the materials. Modification of BC by incorporation of lysozyme (an enzyme with antibacterial action that is found in body fluids, saliva, sweat and tears) susceptible sugars such as analogues of N-acetylglucosamine (GlcNAc) was performed during microbial synthesis. In addition, GlcNAc shares the structure of some repeated disaccharide units of glycosaminoglycans, which are essential components of extracellular matrices. It is expected that the incorporation of GlcNAc will make BC more degradable and more relevant for end use, for instance in the biomedical area. Subtle changes were observed in the formation of apatite deposits on various BC-GlcNAc surfaces. However, the GlcNAc content of the BCGlcNAc produced was low (0.36 mole%) compared to other studies (4-18 mole%). The bacterial strain used in our study is different from those reported by others. It is possible that the type of cellulose producing strain influences the incorporation of GlcNAc in BC. This observation suggests that it is worth pursuing this type of investigations to tailor the surface properties of BC to meet the main criteria of mineralized collagen composites such as natural bone and teeth. Such investigations should be complemented by in vitro and in vivo degradation studies. Since BC is an environmentally friendly biopolymer, its use for materials fabrication for a broad range of applications can be envisaged as an alternative to forest resources. A limitation however is the large-scale production of BC-based composites