紫外光交聯之幾丁聚醣衍生物與角蛋白的複合式水凝膠於組織工程的發展

Abstract

燒燙傷是一個嚴重的全球健康議題，目前全球每年有18萬人因燒燙傷而死亡。為了解決這項問題，科學家發展了各式各樣的人工皮膚以及替代物。其中，水凝膠型態的組織支架對皮膚傷口復原是一個具有前景的選擇，不只是因為它能夠提供濕潤的環境促進傷口修復，同時它也能吸收傷口所滲出的血液、組織液等。在這項研究中，我們使用了兩種不同的天然高分子來製作能夠透過照射紫外光交聯的水凝膠，以作為皮膚組織工程的相關應用。 角蛋白是富含於自然界中的一種結構性蛋白，常見於頭髮、指甲和羽毛等生物組織中，其胺基酸序列組成具有許多對細胞友善的利基，能夠和細胞膜上的受體交互作用，促進貼附和生長等現象，同時也具有良好的生物降解性，因此在過去常被用於製作生醫材料，然而因為其固有的雙硫鍵結構，使其的可加工性受到很大的侷限。透過化學萃取方式，我們將人類頭髮中的角蛋白萃取出來，並經由化學改質，使其具備水溶性與紫外光交聯等特性，以將其製備成水凝膠。 幾丁質是常見於節肢動物外骨骼中的成分，透過處理能夠將其製成甲殼素，應用於工業、醫藥與美容等領域，其特點在於具有良好的生物相容性以及生物降解性，以及作為調整機械性質的材料，此外其特有的陰電性質也被指出具有誘導幹細胞進行軟骨分化的能力。實驗中我們使用水溶性甲殼素，並對其做化學修飾使其具備紫外光交聯的性質，以用於光交聯水膠之開發。 在此研究中，藉由將修飾過的角蛋白和修飾後之水溶性甲殼素混合，製備出具有快速交聯能力和理想機械強度的水凝膠。過程中，我們將探討萃取出的角蛋白之性質、對角蛋白和甲殼素進行化學修飾的效果，使用紫外光使水凝膠交聯並評估水凝膠的機械強度和降解速度等。為了調查細胞在水凝膠的表現，我們將細胞種植在水凝膠表面，觀察細胞貼附、生長能力還有細胞毒性的測試。

Burns are a crucial global health problem. An estimated 180,000 deaths are caused by burns annually. To prepare the antidote for this problem, scientists develop various artificial skin and skin substitutes. A hydrogel system is a promising candidate for skin wound healing. Not only because of its high water-content to offer a moist environment for healing, but also its ability to absorb the blood and the extracellular fluid in the wound site. In this study, we utilized different natural polymers as materials to fabricate a UV-crosslinkable hydrogel system for skin tissue engineering. Keratin is a kind of structural protein common in animal tissues, such as hair, nail, feather, and so on. Due to the excellent biodegradability and biocompatibility, keratin was frequently used as biomaterials. The cell-binding motifs in its peptide sequences, such as leucine-aspartic acid-valine (LDV) and glutamic acid-aspartic acid-serine (EDS), can interact with receptors on cell membranes to promote cell adhesion and proliferation. Nonetheless, because of its intrinsic disulfide bond structure, its processability has significantly been constrained. In this study, we extracted keratin from human hair with the chemical method. Further, we chemically modify the keratin to make it water-soluble and UV-crosslinkable. Chitosan, a kind of polysaccharide, is made from chitin shells of the crustaceans. Its characteristics include outstanding biocompatibility, biodegradability, and simple to control the mechanical strength. Furthermore, its unique electronegativity is indicated to lead stem cell to chondrogenic differentiation. Therefore, in developing a UV- triggered hydrogel system, we choose water-soluble chitosan (glycol chitosan) as the other supporting material, and then chemically modify it to become UV-crosslinkable. In this research, we combined the chemically modified keratin and glycol chitosan to fabricate a fast crosslinking hydrogel with ideal mechanical strength. In the processes, the characteristics of extracted keratin were assessed. The degree of grafting was also measured. Further, we examined the surface morphology, the mechanical strength and the speed of degradation. To investigate the biocompatibility, we cultured L929 cells on hydrogel surfaces to observe the performance of the cell adhesion, proliferation, and the cytotoxicity.