纖維素奈米纖維與聚胜肽之奈米混摻水膠:合成、製備、微結構與性質研究

Abstract

隨著行動裝置的普及，人們長時間注視螢幕的時間逐漸增長，使罹患視神經相關疾病機率提高。有別於其他組織，視神經並沒辦法自我修復。近年來有許多學者投入視神經相關的組織工程研究，在體外細胞實驗有豐碩的成果，但礙於手術執行的困難性以及材料的成本，這些生醫材料仍無法大規模製造及應用於臨床治療。 因此，我們利用纖維素奈米纖維及水溶性聚胜肽製備一種可注射、低生物毒性且合成成本相對低的水膠材料。我們預期注射時的剪應力能促使纖維素奈米纖維在成膠時形成有方向性的排列，並藉此引導神經軸突生長。為了最佳化材料參數以達到上述目標，我們系統性地研究前驅水溶液濃度、膠聯劑種類及製備方式對水膠材料的微結構與其性質之影響。 綜合實驗結果，雖然以注射製備水膠並沒辦法達到長程的方向性排列，但在偏光顯微鏡下能觀察到局部區域有明顯的雙折射性，證明纖維素奈米纖維在這些區域可能有規整且密集的排列。我們發現使用前驅水溶液的濃度與水膠機械強度有正向關係，但與含水量為負相關。此外，低濃度的聚胜肽前驅溶液就可以大幅提升水膠的機械性質並維持水膠含水量在90%以上。這個結果證明聚生態與纖維素奈米纖維間有非常強的交互作用，因此聚胜肽是非常有效的交聯劑。但目前無法斷言除了氫鍵及粒徑的影響之外，是否還有其他機制促成兩者之間的強交互作用。在生物活性試驗中，由高濃度聚胜肽水溶液製備的水膠對PC12細胞有明顯毒性，而鈣離子膠聯的纖維素奈米纖維水膠則沒有細胞毒性。有許多文獻提到高濃度聚胜肽的細胞及生物毒性，並且提出細胞生理學的機制作為解釋。藉由這些實驗數據，後續研究者可以更容易調控纖維素奈米纖維與聚胜肽混摻水膠的性質以符合實驗或應用之需要。

In the Information Age, people spend more time reading screens and suffer from ophthalmological diseases. Optical nerves cannot be regenerated once they are damaged. Though researchers employed stem cells and biomaterials for tissue engineering and achieved some success of nerve regeneration in the lab, the cost of biomaterials and the difficulty of surgery in ophthalmology hinder these biomaterials from mass-production and applications in clinic. By using cellulose nanofibers and polypeptides, we fabricated injectable hydrogels with low cost in synthesis. After extrusion, these CNFs hydrogels are expected to be low-cytotoxic and exhibit anisotropic microstructure to guide neurite growth. We systematically studied the effect of crosslinker types, concentration of precursors, and fabrication methods on their microstructures and properties. Polypeptides significantly enhance the complex modulus of their CNFs hydrogels. The strong interaction between polypeptides and CNFs might due to the size of polypeptides particles and hydrogen bonds between the two macromolecules. Also, the CNFs self-assemble into a compact microstructure with birefringence due to the diffusion of polypeptides. The concentration of precursors has a positive correlation with the mechanical strength but a negative correlation with the water content of their CNFs hydrogels. In the cell viability test, the CNFs hydrogels crosslinked by calcium or low concentration of polypeptides are non-toxic to PC12 cells. The extrusion process slightly promotes the CNFs orientation in the hydrogels, but overall the microstructures of CNFs hydrogels have no specific direction.