Fabrication and investigation of a biocompatible microfilament with high mechanical performance based on regenerated bacterial cellulose and bacterial cellulose

Abstract

A high-strength regenerated bacterial cellulose (RBC)/bacterial cellulose (BC) microfilament of potential use as a biomaterial was successfully prepared via a wet spinning process. The BC not only consists of a 3-D network composed of nanofibers with a diameter of several hundred nanometers but also has a secondary structure consisting of highly oriented nanofibrils with a diameter ranging from a few nanometers to tens of nanometers which explains the reason for the high mechanical strength of BC. Furthermore, a strategy of partially dissolving BC was used and this greatly enhanced the mechanical performance of spun filament and a method called post-treatment was utilized to remove residual solvents from the RBC/BC filaments. A comparison of structure, properties, as well as cytocompatibility between BC nanofibers and RBC/BC microfilaments was achieved using morphology, mechanical properties, X-ray Diffraction (XRD) and an enzymatic hydrolysis assay. The RBC/BC microfilament has a uniform groove structure with a diameter of 50-60μm and XRD indicated that the crystal form was transformed from cellulose Iα to cellulose III and the degree of crystallinity of RBC/BC (33.22%) was much lower than the original BC (60.29%). The enzymatic hydrolysis assay proved that the RBC/BC material was more easily degraded than BC. ICP detection indicated that the residual amount of lithium was 0.07mg/g (w/w) and GC-MS analysis showed the residual amount of DMAc to be 8.51μg/g (w/w) demonstrating that the post-treatment process is necessary and effective for removal of residual materials from the RBC/BC microfilaments. Also, a cell viability assay demonstrated that after post-treatment the RBC/BC filaments had good cytocompatibility.

Bacterial Cellulose-Modified Polyhydroxyalkanoates Scaffolds Promotes Bone Formation in Critical Size Calvarial Defects in Mice

“…The scaffolds biocompatibility depends on the cell behavior after direct contact, and especially to the adhesion ability on their surface. Our in vitro results showed the ability of BC to promote cell adhesion to the PHB scaffolds, and to promote cell growth and proliferation, while regenerated bacterial cellulose/microfilaments of bacterial cellulose provided good cytocompatibility on a cell viability assay [35].…”

High-Strength Superstretchable Helical Bacterial Cellulose Fibers with a “Self-Fiber-Reinforced Structure”

“…27,28 These regenerated cellulose II crystals and the amorphous cellulose macromolecular chains as continuous phases wrapped the undissolved cellulose I nanofiber to form a "self-fiber-reinforced structure", which contributes to rigidity of the spinning macrofiber. 10 When the dissolution time reaches 20 h, the overlapping peaks are assigned to cellulose II at approximately 20.4 and 21.9°. It implies that the nanofibers are almost completely dissolved to form an aggregation structure dominated by cellulose II crystals.…”

“…33 As shown in Figures 2e,f and S3b, the surface and cross-sectional SEM images of the fiber confirm the above result. 34,35 Although there are relatively obvious grooves on the surface of the dry-wet spinning fibers (Figure 2f), which may be caused by the loss of exchange moisture during the drying process, 4,10,36 the denser structure of the macrofibers would be beneficial to the improvement of the mechanical properties. Table S1 lists the tensile mechanical properties of BC macrofibers for different BC concentrations (2, 4, 6 wt %) and different dissolution times (8, 10, 12, 14, 16 h) of BC.…”

“…It can be seen that when the spinning solution concentration is 4 wt % and the dissolution time is 14 h, the tensile strength of the macrofiber reaches the maximum value of 649 MPa. 10 Under these conditions, we can obtain the homogeneous spinning dope for continuous spinning. When the concentration is increased or the dissolution time is less than 14 h, the degree of cellulose dissolution is not enough to form uniform spinning.…”

“…At present, the main solvents used to dissolve cellulose are NaOH/urea solution, 6 N-methylmorpholine-N-oxide monohydrates, 7 ionic liquids (ILs), 8,9 and N,Ndimethylacetamide (DMAc)/lithium chloride (LiCl). 10 By virtue of the dissolution process, using DMAc/LiCl as the solvent is simple and does not require energy supply of temperature and pressure, so it is widely used in laboratory research. 11 Spinning high-strength BC macrofibers by adjusting the spinning process and the presentation form of BC are the basic requirements for expanding the application.…”