Bacterial nanocellulose properties

The extraordinary physical and mechanical properties of BNC pellicles arise from their xmique nanostructure. Well-separated nano- and microfibrils of microbial cellulose create an extensive surface area, which combined with its highly hydrophilic nature, results in a very high liquid loading capacity (i.e., 98-99% for water, much higher than plant cellulose), while maintaining a high degree of conformability [46]. 

Hydrogen bonds between the fibrillar units stabilize the whole structiue and confer its high mechanical strength [6,47]. The BNC behaves like a viscoelastic material brittle failure has previously been reached at approximately 20% strain and 1.5 MPa stress under uniaxial tension [48]. Youngs modulus of BNC single fibrils of 114 GPa have been reported [49]. 

In vivo tests of BNC on animal models have shown no macroscopic signs of causing any inflammation, toxic or allergic side effects, indicating the biocompatibility of the nanomaterial, which is one of the main requirements for its use as biomedical material [50-53]. Another interesting feature of BNC is that nanofibers are immobilized in a stable network, an important aspect considering the health risks associated with mobile nanoparticles. Table 2.2 summarizes the most important properties of BNC. 

The mentioned characteristics of BNC, as well as other properties such as, for example, its capability of maintaining a moist environment at the wound surface while preventing external bacteria entry, the possibility of designing the shape of the membranes obtained, its ease of sterilization, good permeability, and nontoxicity, makes BNC a very promising biomaterial to be used as woimd-dressing material. Details on the physical and mechanical properties of microbial cellulose which promote its use as wound-dressing material are summarized in Table 2.3. 

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One recent example of the formation and application of foils/membranes of unmodified bacterial nanocellulose is described by George and coworkers [35]. The processed membrane seems to be of great relevance as a packaging material in the food industry, where continuous moisture removal and minimal-oxygen-transmission properties play a vital role. The purity, controllable water capacity, good mechanical stability, and gas-barrier... 

Referring to microbial cellulose applications, bacterial nanocellulose has proven to be a remarkably versatile biomaterial with use in paper products, electronics, acoustic membranes, reinforcement of composite materials, membrane filters, hydraulic fracturing fluids, edible food packaging films, and due to its unique nanostructure and properties, in numerous medical and tissue-engineered applications (tissue-engineered constructs, wound healing devices, etc). 

In the current chapter, the synthesis (with particular focus on static versus agitated processes), properties and applications of bacterial nanocellulose, which have been herein briefly introduced, will be reviewed in detail. 

Bacterial nanocellulose has the same molecular formula as plant cellulose, but it is fundamentally different because of its nanofiber architecture, which results in unique properties. Bacteria-produced ribbons typically show rectangular cross-sections with thicknesses aroxmd 3-10 nm, 30-100 nm in width, and 1-9 xm in length [39,40,41]. Figure 2.4 shows electron... 

Cellulosic source, processing conditions, functions, dimensions, and pretreatment methods have great influence on the properties and type of nanocellulose. There are three main subcategories of nanocellulose microfibrillated cellulose, nanociystalline cellulose, and bacterial nanocellulose. 

Nanocellulose, such as that produced by the bacteria Gluconacetobacter xylinus (bacterial cellulose, BC), is an emerging biomaterial with great potential in several applications. The performance of bacterial cellulose stems from its high purity, ultra-fine network structure and high mechanical properties in the dry state [114]. These features allow its applications in scaffold for tissue regeneration, medical applications and nanocomposites. A few researchers have used bacterial cellulose mats to reinforce polymeric matrices and scaffolds with wound healing properties [115-121]. BC is pure cellulose made by bacterial fabrication via biochemical... 

Cho M, Park B (2011) Tensile and thermal properties of nanocellulose-reinforced poly (vinyl alcohol) nanocomposites. J Ind Eng Chem 17 36-40 Ciechanska D (2004) Multifunctional bacterial cellulose/chitosan composite materials for medical applications. Fibres Text East Eur 12 69-72... 

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