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

- Bacterial cellulose nanocrystals (BCNCs) with a highly oriented nanofibril bundle structure have been prepared.
- A secondary hyperfine structure consisting of nanofibrils with diameters of just several nanometers has been investigated.
- A novel strategy involving partial dissolution BC greatly enhanced the mechanical performance of the spun filaments.
- A post-treatment process was utilized to remove residual solvents from the RBC/BC fibers to ensure biocompatibility.

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 50-60 μm and XRD indicated that the crystal form was transformed from cellulose Iα to cellulose IIII 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 0.07 mg/g (w/w) and GC-MS analysis showed the residual amount of DMAc to be 8.51 μg/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.

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