RESUMEN
Bacterial cellulose (BC) is a fascinating polymer with a three-dimensional structure formed by nanofibers of pure cellulose, synthesized by some bacteria and organized as a coherent network. Its biocompatibility and remarkable mechanical properties have promoted scientific interest for its use in a variety of applications including biomedical, electrical, among others. However, it is the possibility of incorporating nanosized materials into the coherent 3-D network structure displayed by BC what has propelled multiple investigations on the development of BC nanocomposites for different applications. Here we report the different methods and techniques used so far for the BC nanocomposites production. We have focused on the processing techniques that allow the incorporation of functional nanoreinforcements, nanofillers and additional phases without disturbing the original network structure, leading to the formation of nanomaterials. Processing methods, resulting structure-property relationships and potential applications of these novel nanocomposites are discussed and showcased as a fair example of integrated design and manufacture of materials.
Asunto(s)
Bacterias/química , Materiales Biocompatibles/química , Celulosa/química , Nanocompuestos/química , Nanofibras/química , Nanoestructuras/química , Polímeros/químicaRESUMEN
Fish scales from the Amazonian fish Arapaima gigas have been characterised to study their impact and fracture behaviour at three different environmental conditions. Scales were cut in two different directions to analyse the influence of the orientation of collagen layers. The energy absorbed during impact tests was measured for each sample and SEM images were taken after each test in order to analyse the failure mechanisms. The results showed that scales tested at cryogenic temperatures display fragile behaviour, while scales tested at room temperature did not fracture. Different failure mechanisms have been identified, analysed and compared with the failure modes that occur in bone. The impact energy obtained for fish scales was two to three times higher than the values reported for bone in the literature.
Asunto(s)
Peces/fisiología , Fenómenos Fisiológicos de la Piel , Piel/química , Animales , Fuerza Compresiva , Dureza/fisiología , Ensayo de Materiales , Estrés MecánicoRESUMEN
Starch is a natural material extracted from roots, seeds, stems and tubers of different plants. It can be processed as a thermoplastic to produce a variety promising products for biomedical applications, including foams, sheets and films. In the present work, we investigated the immunological properties of microfilms prepared with starches extracted from six different types of Andean potatoes and their relationship with the different film-surface features. We confirmed the biocompatibility of all the films using THP-1 human monocytes, noticing only slight decrease in cell viability in two of the tested starches. We also analyzed pro-inflammatory cytokine release and immune cell surface receptor modulation on THP-1 plated onto the films. Our data show differences in the immunological profile of the same cells cultured onto the different starch films. Furthermore, we examined whether the dissimilar stiffness or the nanometric roughness of the films might influence the immune stimulation of the THP-1 monocytes. Our results demonstrate no correlation between cultured THP-1 immune activation and surface film characteristics. We conclude that different Andean native potato starch films have specific ability to interact with cell membranes of immune cells, conceivably due to the different spatial localization of amylose and amylopectin in the diverse starches.
Asunto(s)
Fenómenos Mecánicos , Nanopartículas/química , Almidón/química , Almidón/inmunología , Materiales Biocompatibles/farmacología , Línea Celular , Supervivencia Celular/efectos de los fármacos , Citocinas/metabolismo , Humanos , Mediadores de Inflamación/metabolismo , Ensayo de Materiales , Microscopía de Fuerza Atómica , Receptores Inmunológicos/metabolismo , Propiedades de SuperficieRESUMEN
Dosidicus gigas is the largest and one of the most abundant jumbo squids in the eastern Pacific Ocean. In this paper we have studied the muscle of the mantle of D. gigas (DGM). Morphological, thermal and rheological properties were assessed by means of atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, thermogravimetry and oscillatory rheometry. This study allowed us to assess the morphological and rheological properties of a collagen based network occurring in nature. The results showed that the DGM network displays a nonlinear effect called reversible stress softening (RSS) that has been previously described for other types of biological structures such as naturally occurring cellulose networks and actin networks. We propose that the RSS could play a key role on the way jumbo squids withstand hydrostatic pressure. The results presented here confirm that this phenomenon occurs in a wider number of materials than previously thought, all of them exhibiting different size scales as well as physical conformation.
Asunto(s)
Colágeno/metabolismo , Músculos/metabolismo , Actinas , Animales , Colágeno/química , Decapodiformes , Módulo de Elasticidad , Presión Hidrostática , Músculos/química , Reología , Temperatura , Agua/químicaRESUMEN
Different Andean crops were used to obtain starches not previously reported in literature as raw material for the production of biodegradable polymers. The twelve starches obtained were used to prepare biodegradable films by casting. Water and glycerol were used as plasticizers. The mechanical properties of the starch based films were assessed by means of tensile tests. Compost tests and FTIR tests were carried out to assess biodegradability of films. The results show that the mechanical properties (UTS, Young's modulus and elongation at break) of starch based films strongly depend on the starch source used for their production. We found that all the starch films prepared biodegrade following a three stage process and that the weight loss rate of all the starch based films tested was higher than the weight loss rate of the cellulose film used as control.
Asunto(s)
Productos Agrícolas/química , Plásticos/síntesis química , Almidón/aislamiento & purificación , Biodegradación Ambiental , Ensayo de Materiales , Perú , Plásticos/química , Espectroscopía Infrarroja por Transformada de Fourier , Almidón/química , Resistencia a la TracciónRESUMEN
Byssus fibres are tough biopolymer fibres produced by mussels to attach themselves to rocks. In this communication, we present the mechanical properties of the byssus from the South American mussel Aulacomya ater which have not been previously reported in the literature. The mechanical properties of the whole threads were assessed by uniaxial tensile tests of dry and hydrated specimens. Elastoplastic and elastomeric stress-strain curves were found for byssal threads from A. ater in the dry and hydrated state, respectively. The results obtained from mechanical tests were modelled using linear, power-law-type and Mooney-Rivlin relationships. These methods for dealing with tensile measurements of mussel byssus have the potential to be used with other stretchy biomaterials.