Nanocellulose membranes

Keywords Nanocelluloses Membranes Composites Medical devices ... 

Recent advances in the field of biomaterials and their medical applications indicate the significance and potential of various nanoceUulose in the development of novel classes of medical devices and applications in healthcare and veterinary medicine. The physical and mechanical properties of nanocellulose are attributes that enable nanocellulose membranes to function as effective temporary wound dressings. On the other hand, because implantable biomaterials (i.e., scaffolds) are also needed, a new approach has been undertaken to apply cellulose as a material entirely integrated into the body, either as a bone or skin graft. 

The nanocellulose membranes were used to repair defects of the abdominal wall in humans or animals. NanoceUulose may be used as treatment of great abdominal... 

Because of the extraordinary supramolecular structure and exceptional product characteristics as high-molecular and high-crystalline cellulosics with a water content up to 99%, nanocelluloses require increasing attention. This review assembles the current knowledge in research, development, and application in the field of nanocelluloses through examples. The topics combine selected results on nanocelluloses from bacteria and wood as well as their use as technical membranes and composites with the first longtime study of cellulosics in the animal body for the development of medical devices such as artificial blood vessels, and the application of bacterial nanocellulose as animal wound dressings and cosmetic tissues. 

Membranes and composites from cellulose and cellulose esters are important domains in the development and application of these polymer materials. The most important segment by volume in the chemical processing of cellulose contains regenerated cellulose fibers, films, and membranes, hi the case of the cellulose esters mainly cellulose nitrate and cellulose acetate as well as novel high-performance materials created therefrom are widely used as laminates, composites, optical/photographic films and membranes, or other separation media, as reviewed in [1], The previously specified nanocelluloses from bacteria and wood tie in with these important potentials and open novel fields of application. 

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... 

The cultivation of BC in the presence of N-acetyl glucosamine (GlcNAc) causes a variation of the polymer formation by the insertion of GlcNAc units. It is possible to produce very thin membranes of the nanocellulose-chitin hybrid formed in this way [36]. 

The second chapter by Dieter Klemm, Dieter Schumann, Hans-Peter Schmauder, and coworkers focuses on the recent knowledge of cellulosics characterized by a property-determining supramolecular nanofiber structure. Topics in this interdisciplinary contribution are the types of nanocelluloses and their use in technical membranes and composites as well as in the development of medical devices, in veterinary medicine, and in cosmetics. 

Changing the surface functionality of the cellulose nanoparticle can also affect the permeability of nanocellulose films. Films constituted of negatively charged cellulose nanowhiskers could effectively reduce permeation of negatively charged ions, while leaving neutral ions virtually unaffected. Positively charged ions were found to accumulate in the membrane [70]. 

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). 

Today, electronics are manufactured with expensive materials that often contribute to the increase of pollution and are rarely recyclable. The market of printed electronic is expanding rapidly and therefore needs new materials that could help revolutionize the electronic industry and would be relative inexpensive. Nanocellulose, one of the most common, cheapest, and reqrclable substrate materials, is believed to be able to successfully replace plastic, metallic foil or paper substrates currently used for manufacturing flexible electronics [81, 82]. The authors of article [81] studied composites made of inoi anic filler particles and cellulose nanofibers for printed electronics applications. In their research, nanocellulose was assumed to fill voids of the structure. On the other hand, Caspar et al. worked on "nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors [82]. Figure 21.42 presents transmittance of two NCC membranes produced by two approaches NCC evaporation and NCC casting. 

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