RESUMEN
Bacterial nanocellulose (BNC) has a negative surface charge in physiological environments, which allows the adsorption of calcium ions to initiate the nucleation of different calcium phosphate phases. The aim of this study was to investigate different methods of mineralization in three-dimensional microporous bacterial nanocellulose with the intention of mimicking the composition, structure, and biomechanical properties of natural bone. To generate the 3D microporous biomaterial, porogen particles were incorporated during BNC fermentation with the Komagataeibacter medellinensis strain. Calcium phosphates (CPs) were deposited onto the BNC scaffolds in five immersion cycles, alternating between calcium and phosphate salts in their insoluble forms. Scanning electron microscopy (SEM) showed that the scaffolds had different pore sizes (between 70 and 350 µm), and their porous interconnectivity was affected by the biomineralization method and time. The crystals on the BNC surface were shown to be rod-shaped, with a calcium phosphate ratio similar to that of immature bone, increasing from 1.13 to 1.6 with increasing cycle numbers. These crystals also increased in size with an increasing number of cycles, going from 25.12 to 35.9 nm. The main mineral phase observed with X-ray diffraction was octacalcium dihydrogen hexakis phosphate (V) pentahydrate (OCP). In vitro studies showed good cellular adhesion and high cell viability (up to 95%) with all the scaffolds. The osteogenic differentiation of human bone marrow mesenchymal stem cells on the scaffolds was evaluated using bone expression markers, including alkaline phosphatase, osteocalcin, and osteopontin. In conclusion, it is possible to prepare 3D BNC scaffolds with controlled microporosity that allow osteoblast adhesion, proliferation, and differentiation.
RESUMEN
Fique fibers, native to Colombia, are traditionally used for ropes and bags. In the extraction of long fibers for these purposes, the same amount of short fibers is generated; the short fibers are then discarded in the soil or in landfills. This agro-industrial waste is cellulose-rich and can be potentially developed into new biobased products. As an alternative use for these fibers, viscose regenerated fibers with potential applications in the textile industry were developed. Fique waste fibers were pulped (to produce fique cellulose pulp, FCP) using a 3³ design of experiment (DOE) to adjust the variables of the whitening treatment, and DOE analysis showed that time and hydrogen peroxide concentration do not have a significant effect on non-cellulosic remotion, unlike temperature. The behavior of this pulp in the production of viscose was compared against that of commercially available wood cellulose pulp (WCP). FCP showed a suitable cellulose content with a high degree of polymerization, which makes it a viable pulp for producing discontinuous viscose rayon filaments. Both pulps showed the same performance in the production of the viscose dope and the same chemical, thermal, and mechanical behavior after being regenerated.