Preparation And In Vitro Degradation Studies Of Cellulose Nanofibrils3-Dimensional Tissue Engineering Scaffolds

Cellulose is the most abundant carbon hydrate polymers in nature, and research ofcellulose nanofibrils （CNFs） used as tisssue engineering scaffold has attracted widely attenton.In addition, C6carboxyl oxidized cellulose has been widely used in medical hemostaticmaterials in present owing to its unique bioabsorbable performance. Therefore, preparation ofC6carboxyl oxidized cellulose nanofibrils scaffold and its application in tissue engineeringscaffold provide a direction for the further application of CNFs scaffold.The TEMPO/NaClO/NaClO₂system under neutral condition was applied to eucalyptuspulp. In our early research, we had discovered the superiority of changing the adding order ofreagent in TEMPO/NaClO/NaClO₂system. And on this basis, we made a further research onthe oxidation discipline of this system and got the efficiently preparation routes for oxidizedcellulose with high content of carboxyl. Combined with high pressure microfluidhomogenization, CNFs were prepared continuously and characterized. The as-prepared CNFswas used for the fabrication of pure CNFs scaffold using solvement casting and freeze drying.And the microstructure, morphology and mechanical properties of the CNFs scaffolds wereanalyzed. The in vitro degradation performance of CNFs scaffolds immersed in simulatedbody fluids （SBF） were investigated. In addition, the microstructure, morphology and massloss of CNFs scaffold immersed in SBF with different time were evaluated, so as to provide adirection for in vivo transplantation of CNFs scaffolds in future. The results are showed asfollows.1. In our early research, we have discovered the TEMPO/NaClO/NaClO₂system hadbetter performance when the adding order of reagent was changed from TEMPO, NaClO,NaClO₂to TEMPO, NaClO₂, NaClO. And on this basis, the carboxyl content of oxidizedcellulose went to0.80mmol/g with only8h when the solid-liquid ratio was further changedfrom1:100to1:66.7and the amount of TEMPO was decreased from0.1mmol/g cellulose to0.05mmol/g cellulose.2. Atomic force microscopy images showed that the fibers morphology were ribborn-like and were of20nm in width and up to μm in length as a result of OC passed4times throughD8nozzle. That the as-prepared fiber described above further passed4times through D5nozzle went to rod-like and the width of fiber decreased to15nm and the length of fiberdecreased to100-200nm. Furthermore, the tensile strength and elongation of films preparedfrom CNFs suspension were increased with the increase of homogenization intensity. And theYoung’s modulus of CNFs scaffolds were7.3±1.8Gpa.3. Scanning electronic microscopy images showed that CNFs scaffolds had gradient porediameters and interconnected pore structure, and the diameters of pores were up to200μm.,and many microfilaments connected on the surface of scaffold. In addition, the compressivemodulus of the scaffolds were about20KPa which were suit for the culture of muscle tissuecell. The mass loss of CNFs scaffolds went to13%after immersed in SBF for4weeks. Therewere no differences of the morphology and microstructure among scaffolds which preparedthrough different homogenization routes in vitro degradation process.