Electrospun Nanocellulose: A New Biomaterial

Science and engineering studies on biocompatible implantable materials for tissue and organ repair have recently focused on polymeric materials to serve as scaffolds for cellular integration. Cellulose in many forms has been demonstrated as potential biopolymer for tissue engineering; however, it has not been previously electrospun into a scaffold for tissue engineering applications. The overall goal of this research project was to produce electrospun cellulose acetate (CA) nanofibers with specific architectures and surface chemistries to be evaluated as scaffolds for tissue regeneration. The size and morphology of electrospun CA was impacted by polymer concentration, solvent system, and solution flow rate. The conversion of CA electrospun scaffolds into regenerated cellulose by exposure to NaOH ethanol solution was successful for scaffolds produced at polymer solution flow rate of at least 1 mL/h. The regeneration process resulted in minimal degradation of the cellulose while retaining the original fiber structure of the scaffold. In vitro cytotoxicity evaluation of the fibrous cellulose scaffolds on a culture of mouse fibroblast (L-929) cells indicated that this material posed no threat to mammalian cells.

Electrospun cellulose scaffolds with different architectures and surface chemistries were designed and evaluated to enhance scaffold properties and cell adhesion. The morphology of the partially regenerated cellulose revealed only a broad diffraction peak for the scaffold material, while the fully regenerated cellulose showed a characteristic semi-crystalline cellulose II diffraction pattern. Fiber orientation and porosity of the scaffolds were controlled by electrospining CA solution onto the edge of a rotator wheel and laser microablation, respectively. Bioactivity of the scaffolds was shown to be enhanced via scaffold surface modification with either anionic or cationic functional groups. Biomimetic Ca-P crystal mineralization on electrospun cellulose fibers was produced by means of carboxymethyl cellulose (CMC) adsorption and treatments with simulated body fluid (SBF) or phosphate buffer saline (PBS) solutions. Porosity and Ca-P crystals enhanced osteoprogenitor cell adhesion on the electrospun cellulose scaffolds. Cationic modification by trimethyl ammonium betahydroxy propyl (THAMP) derivation and adsorption of extracellular matrix proteins on cellulose fibers promoted adhesion and proliferation of neural-like (PC12) and myoblast (C2C12) cells. Differentiation of myoblast cells (C2C12) towards myotubes on electrospun cellulose scaffolds was controlled by surface chemistry and mechanical properties. Together these studies showed great potential for cellulose acetate to be electrospun and converted into a viable biocompatible tissue engineering scaffolds.