奈米碳管/幾丁聚醣複合材料於神經組織工程之應用

Abstract

周邊神經受損斷裂後，神經可藉由軸突的再生而重新連接缺口兩端的神經。組織工程上，利用神經導管作為橋接斷裂神經之間的聯繫，期許能夠有效的達成神經功能修復的目的。近年來，已有多方的研究在於利用幾丁聚醣及其他高分子材料製成之神經導管，顯示具有良好的生物相容性及生物可降解性。而奈米碳管（CNT）由於其結構特性，因此具有獨特的力學與電學性質。本研究之目的，在於利用幾丁聚醣混合奈米碳管作為製成神經導管的複合材料，期許奈米碳管可提升複合材料的機械強度及導電性質，並同時具有幾丁聚醣的生物相容性及生物可降解性。 實驗上，將奈米碳管/幾丁聚醣之複合材料經自然風乾製成薄膜，並利用流體動力聚焦及共凝集法製成纖維，於SEM下均可見到由奈米碳管所構成的奈米級結構。經由材料物理性質（機械、電學性質）測試，發現奈米碳管/幾丁聚醣薄膜之機械強度與導電度均較幾丁聚醣薄膜高，顯示加入奈米碳管可提升複合材料的機械強度與導電度。經過MTT及LDH分析測試，可得知奈米碳管/幾丁聚醣複合材料並不具細胞毒性。利用氧氣電漿表面改質技術，可將表面改質成較為親水的特性，使水接觸角降低至小於10度，而此改質過後的材料能夠更有利於接枝層粘連蛋白。此外，材料經過接枝層粘連蛋白後，確實能夠提升PC12細胞對於材料的親和性，使貼附比率增加。經由免疫螢光染色及SEM下觀察結果，可發現PC12細胞能夠順利於奈米碳管/幾丁聚醣薄膜及纖維上貼附並分化；而在纖維上的PC12細胞，其軸突更能夠沿著纖維呈現有方向性的生長，顯示此纖維具備有導引神經細胞生長方向的作用。

After peripheral nerve damage, nerve regenerates by re-connecting at both ends of the nerve gap. The tissue engineering for nerve regeneration use nerve conduit as a neural link between the nerve gap that can effectively achieved rehabilitation of neurological function. In recent years, many nerve conduits have been made by chitosan and other polymers, showing good biocompatibility and biodegradability. Due to the structure of carbon nanotube（CNT）, it has unique mechanical and electrical properties. The purpose of this study is to use chitosan and carbon nanotubes mixture as composite material to manufacture a nerve conduit, wish that CNT can enhance the mechanical strength and electrical conductivity of the composite, and also have the biocompatibility and bioresolvability of chitosan.

In the experiment, the CNT/chitosan thin film can be fabricate by natural dried, and the fiber can be made by using of hydrodynamic focusing and coaggulation method. Both of them can be seen the nano-scale structure formed by carbon nanotubes from the SEM image. By the physical properties (mechanical and electrical properties) tests, it was found that the mechanical strength and electrical conductivity of CNT/chitosan films were higher than chitosan films, showing that adding CNT can enhance the mechanical strength and electrical conductivity of the composite. The MTT and LDH tests showed CNT/chitosan composite materials do not exhibit cell toxicity. By using oxygen plasma surface modification technology, surface can be modified for more hydrophilic such that water contact angle was reduced to less than 10 degrees, a significant improvement for laminin graft. Furthermore, after the laminin graft, the composite showed enhancement of the affinity of PC12 cells to the material, evidence by the increase of adhesion ratio. The immunofluorescence staining and SEM images results showed PC12 cells can successfully adhere and differentiate on the CNT/chitosan films and fibers; and the PC12 axons are more extended by following the fibers with a directional growth, indicating that these fibers can guide nerve cells to have a role in the growth direction.