幾丁聚醣因具有生物分解性、無毒性、良好的生物相容性及價格便宜，而且可從廢棄的蝦蟹殼中大量取得等優點，所以已經被用於生醫材料方面。本研究藉由幾丁聚醣來作為人工披覆物的材料，並利用兩種不同的製程及冷凍乾燥過程製造出幾丁聚醣非對稱薄膜。此兩種製程第一種為：乾/濕式合併相轉換製程;而第二種製程則為濕式相轉換合併熱處理製程。利用此兩種方法可製出不同條件的薄膜，對此非對稱幾丁聚醣薄膜都包含兩層結構：上層為堆積緊密之緻密層，而下為結構酥鬆之海綿體之孔洞層。這兩種結構物分別有著不同的功能，堆積緊密之緻密層將可控制水氣之透過量及提供必要的機械強度；海綿體之孔洞層則負責吸收傷口之滲出液及傷口濕潤的環境。 經由此兩種製程的非對稱幾丁聚醣薄膜在吸水能力、氣體透過、水氣透過、機械性質、藥物穿透及藥物釋放方面都有很明顯的不同。 由濕式相轉換合併熱處理製程所得的薄膜可得到較高的水含量、氣體透過量及包覆AgSD之釋放量；而在乾/濕式合併相轉換製程可得較佳的機械性質、AgSD包覆率及包覆AgSD之控制釋放能力。 對於包覆AgSD之非對稱幾丁聚醣薄膜，不論是經由乾/濕式合併相轉換製程或濕式相轉換合併熱處理製程都可得到兩階段的藥物釋放行為。經濕式相轉換合併熱處理製程的包覆AgSD薄膜，在2000分鐘內第一階段的釋放總量即可快速的達到50-55％；而經乾/濕式合併相轉換製程第一階段的釋放總量也可達35-55％。兩種製程的第二階段AgSD釋放，則呈現較緩慢的釋放趨勢直至8200分鐘。如果於生理緩衝液中添加酵素，則兩階段的釋放機制將轉變成一階段的快速釋放行為。 而抗菌實驗則顯示出，經包覆AgSD的非對稱幾丁聚醣薄膜對於綠膿桿菌、金黃葡萄球菌及大腸桿菌都有明顯的抗菌能力，且抗菌能力可維持四天以上。 Chitosan[β(1→4)-2-amino-2-deoxy-D-glucose] is a natural, abundant , nontoxic, biopolymer and is widely produced commercially from crab and shrimp waste shells .A novel artificial wound dressing is made by chitosan via phase inversion and lyophilization method in this study. Two types of phase inversion were employed: dry-wet process and wet-dry process. The asymmetric chitosan membrane made from our laboratory is consists of two layers in which the upper layer is dense skin and the sub layer is porous. The dense skin acts as the water vapor barrier and provides mechanical strength and the porous part is capable of absorbing wound exudate and provides a moist environment. There were significant differences in water uptaking ability, gas permeation, mechanical strength, water vapor flux, drug pass flux, major structure and AgSD-impregnated in terms of two processes of isothermal process with time changed. For wet-dry process made membrane, It has higher gas permeability, better water uptaking ability and quicker AgSD release rate. For dry-wet-process made membrane, it has higher mechanical strength, better controlled release and more effectively AgSD-impregnated. The release of AgSD from AgSD-impregnated chitosan wound dressing made by the two processes was found to proceed by two-stage release. In the first stage, it has 50-55% rapid release for wet-dry-process prepared membrane and 35-55% release for dry -wet-process prepared one in 2000 min. In the second stage, AgSD was slowly released up to 8200 min. The two-stage behavior of release becomes to one stage when lysozyme is added into PBF buffer. From the in-vitro studies, the antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa, Staphylococcus aureus and E-coli. It was significantly found that the suppression of bacterial proliferation was effective within 4 days when compared with control group.
