石墨烯與聚胺酯複合水膠材料之開發 並應用於細胞3D列印及神經幹細胞分化

Abstract

3D bioprinting是一種目前廣為人知的加成製造技術，其可以將包覆細胞的高度生物相容性材料製作成各種結構，以便於修復受損的組織或器官。在本研究中，我們製備了可以在水中分散良好的石墨烯以及氧化石墨烯，而石墨烯及氧化石墨烯是一種二維的奈米材料且具備良好的導電度以及在神經組織工程上應用的潛力。此外，我們也製備了一種新型的生物可降解水性聚胺酯，其中包含了由聚己內酯二元醇 (2 kDa) 以及DL-聚乳酸二元醇 (1.5 kDa) 所組成的軟鏈段。而此種聚胺酯奈米粒子分散液在以細胞培養液稀釋至固含量25%時，會在接近人體溫度時進行sol-gel的相轉換，並且擁有適合細胞生長的水膠強度。接著我們將石墨烯或氧化石墨烯混摻入此種水性聚胺酯，以形成石墨烯/聚胺酯之奈米複合水膠材料，並將其包覆神經幹細胞，以進行3D bioprinting。由流變性質來看，此種石墨烯/聚胺酯之奈米複合水膠材料的強度不僅有利於細胞生長，更足以撐起整個支架的結構。此外，在僅添加25 ppm濃度之下，即可有效達到促進神經幹細胞分化以及增強細胞代謝的效果，因此由結果可以得知，本研究所製備之石墨烯/聚胺酯之奈米複合水膠十分有潛力成為神經組織工程支架之材料。

3D bioprinting is known as an additive manufacturing technology which builds customized structure from cells and supporting biocompatible materials for the repair of the damage tissues or organs. In this study, we prepared water dispersible graphene and graphene oxide, which are 2D nanomaterials with high conductivity and potential application in neural tissue engineering. Moreover, we synthesized a new biodegradable waterborne polyurethane with the soft segment containing mostly poly(ε-caprolactone) (2 kDa) and twenty molar percent of shorter (1.5 kDa) poly(D,L-lactide). This polyurethane dispersion at 25% solid content in cell culture medium underwent sol-gel transition near human body temperature with proper gel modulus. Afterwards, we mixed the graphene or graphene oxide with the polyurethane to prepare graphene-based nanocomposite hydrogel for neural stem cell (NSC) printing. The rheological properties of the graphene-based nanocomposite hydrogel were suitable for printing and surviving of NSCs. Furthermore, the addition of a very low content (25 ppm) of graphene nanomaterials in the hydrogel significantly enhanced the oxygen metabolism (2- to 4-fold increase) as well as the neural differentiation of NSCs. Taken together, the graphene-polyurethane nanocomposite hydrogel may be possible bioink for printing 3D cell-laden tissue constructs for neural tissue engineering.