0000000000023866
AUTHOR
Omar P. Troncoso
Development of self-assembled bacterial cellulose–starch nanocomposites
Abstract A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)–starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assem…
Reversible stress softening of collagen based networks from the jumbo squid mantle (Dosidicus gigas).
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 …
Characterization of the nanocomposite laminate structure occurring in fish scales from Arapaima Gigas
In the present paper, the nanocomposite laminate structure of scales from the Amazonian fish Arapaima Gigas is investigated. The structure and composition of the scales were assessed by means of X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). The theory of Fickian diffusion is used and discussed in order to rationalize the water absorption and desorption behavior of the scales. Morphology studies and fracture analysis of the native scales were carried out using Transmission Electron Microscopy (TEM), Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM). A fibrous layer of collagen and a plywood-like structure were observed. In order to study the …
Optimization of Cell Growth on Bacterial Cellulose by Adsorption of Collagen and Poly-L-Lysine
Poly-L-lysine and collagen were separately added to bacterial cellulose (BC) nanofibers. The ionic surface charge had been previously modified in order to promote the adsorption of poly-L-lysine and collagen. Cell adhesion of Chinese hamster ovary (CHO) cells on BC surfaces was confirmed by removing unattached cells from the BC substrates. Cell viability was calculated and it was determined that both poly-L-lysine-BC and collagen-BC substrates are viable for cell growth. The results showed that the cell viability in poly-L-lysine modified BC substrate is similar to the one observed in polystyrene tissue culture plates.
Reversible stress softening and stress recovery of cellulose networks
The mechanical properties of the plant cell wall play an important role in communication, differentiation and growth of plant cells. In particular, the expansive growth of plant cells is only possible because the material that forms the plant cell wall yields at a specific stress level, allowing for an increase in cell wall area. This process can be defined in mechanical terms as the relaxation of the wall stress. The current understanding of plant cell growth suggests that such relaxation behaviour occurs due to the presence of wall loosening agents rather than to the properties of the cellulose network itself. It is believed that certain nonenzymatic proteins, acting as wall loosening age…
Morphological Characterisation of Bacterial Cellulose-Starch Nanocomposites
Acetobacter sp. growing medium was modified in order to produce bacterial cellulose (BC) nanocomposites using a bottom-up technique that allowed starch to be introduced into the cellulose network. The BC-starch mats were hot-pressed to obtain nanocomposites sheets. Morphological characterisation was carried out using Atomic Force Microscopy and Environmental Scanning Electron Microscopy. The images obtained from microscopy were then processed using image analysis. Network properties, such as mesh size and fibre orientation were characterised. Fracture surfaces of these new nanocomposites were analysed.