Capítulos > Grupo de Nanoestructuras de Carbono y Nanotecnología (G-CNN)

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CHAPTER 4. Carbon Nanostructures and Polysaccharides for Biomedical Materials

Carbon Nanostructures for Biomedical Applications, 2021, 98-152 Ed. RSC.

Even though many members from the broad family of carbon nanostructures have been known to us for decades, and despite their promising potential in biology and medicine, there is still a long way ahead to reach the goal of using them in real applications. The cause of such a gap still lies in the persistent drawbacks of insolubility, processability difficulties, poor consistency of macroscopic assemblies and surface inertness of carbon nanostructures. However, solely their direct chemical derivatization might not solve the problem right away. New processing elements need to come into play, but this also twists the whole picture, as the toxicity and performance profiles become more complex. We herein analyse the potential of natural polysaccharides (with a particular focus on cellulose) towards hybrid materials and structures for biomedical purposes. The role that these biopolymers acquire when interfacing with carbon nanostructures goes far beyond a mere dispersing effect, but instead creates unprecedented synergies leading to hydrogels, aerogels, films or fibres with high biocompatibility and bioactivity. In this chapter, the history of carbon nanostructures and natural polysaccharides in the field of biomedical applications will be respectively reviewed, to subsequently go into detail of specific hybrids made with the most relevant biopolymers (namely cellulose, chitin, chitosan and alginate) with extraordinary prospects in biomedicine.

Optimizing Bacterial Cellulose Production towards Materials for Water Remediation

Nanoscience and Nanotechnology in Security and Protection against CBRN threats. NATO Science for Peace and Security Series B: Physics and Biophysics.  Chapter 31. Pg 391-403. DOI: 10.1007/978-94-024-2018-0_31. 

Cellulose is a renewable alternative to mass consumption plastics, but its manufacture by the classical methods is not sustainable due to the use of large amounts of strong acids, bases and/or organic species (e.g. ionic liquids) in its production, generating many residues. Bacterial cellulose (BC) has a simpler processing because it is much more cleanly generated. In this work, BC hydrogels, stemming from Komagateibacter xylinus bacteria, has been optimized in terms of bacterial culture and subsequently tailored in their physical properties after drying, giving rise to aerogels and xerogels. These are compared in order to ascertain how the bacterial culture conditions (pH, carbon and nitrogen sources) and the raw hydrogels processing determine their thermal stability, crystallinity index, swelling ratio and flammability. The most notable results are the influence of the drying method on the swelling ratio and the carbon source on the thermal stability. It is possible to control the BC hydrogel properties by rationally selecting the appropriate drying method. In this regard, the aerogels (obtained by lyophilisation) have a much larger sorption capacity and a higher porosity, whereas xerogels (obtained by drying in open air) are more compact, as observed by SEM. Contrary to the aerogels, the BC xerogels are non-flammable. The pH of the culture medium does not have a great influence on the thermal stability of the xerogels and aerogels, but it is important for the hydrogel production rate and slightly influences the CI. The carbon source has a greater influence in the thermal stability of the final materials. Fructose provides a higher thermal stability; however …