利用氮氣為主的常壓電漿束於聚乳酸材料表面快速植入胺基官能基之研究

Abstract

近幾年來，常壓電漿逐漸興起，用途從過去的半導體製程跨到成日常工業，像是表面改質、生醫科技、能源科技甚至是環境工程，都有人將之和常壓電漿作不同程度上的結合。本實驗先由氧氣(0.1%)混合氮氣產生的親水電漿來對聚乳酸(PLA)薄膜表面作前處理(pretreatment)，目的是提升材料表面能，增加表面親水性，同時也提供官能基導入之空缺。接著再轉換成氨氣(5%)混合氮氣產生之電漿，希望藉由電漿產生的氮基官能基導入人工血管表面，以提升後續細胞培養上的生長力、貼附力。此裝置放電區域是由兩塊外面包覆鐵氟龍的金屬平板所產生，並將人工血管材料放在電漿出口的位置加以處理。在初步實驗中，我們先以較快速、方便的方法-水滴接觸角的量測方法來觀察電漿處理的參數對PLA材料表面之影響，從結果可以知道電漿處裡次數、氧氣和氮氣混合比例以及處理距離都會影響到親水性效果。PLA材料由未處理前的82o，經過兩階段製程電漿處理後最多可下降至28o。但親水性的增加不代表官能基同時被導入材料表面，必須藉由FTIR和XPS等儀器來分析表面化學結構和元素比例，才能得知材料表面官能基存在與否。PLA材料表面N1s元素比例經過電漿處理後上升至2.97%，隨著處理次數的增加最高可到達5%。最後對試片進行細胞培養測試，並於培養後定時觀察細胞貼附情形、數量變化、形態等情況。本實驗同時採用了細胞活性測量方法，期望藉由收集細胞代謝出之晶粒數量多寡，來得知細胞在此一材料上之生長情況。由實驗結果可以看出經過電漿處理的PLA試片比起未處理之試片，細胞有良好的貼附率，長時間觀察下也有穩定的形態成長、活性維持。將細胞培養的結果與FTIR和XPS所量測數據交叉比對下，更可以發現胺基官能基(399.2 eV)是真正對細胞生長是有幫助的，以及如何從實驗參數操作下來得到最佳官能基覆蓋率。衰退(aging)和氧化同時是一個很重要的議題，在常壓電漿操作下，試片難免與環境有所接觸，由接觸角實驗中可以觀察到衰退現象隨著時間持續的作用，並於最後達到穩定，詳細的結果在文中會有所描述。

Atmospheric plasma become popular in recent years. It has been used in surface modification, Biomedical Technology, Energy Science, and even environmental engineering. Although not so clean, but the advantage is that low-cost, and fast processing time. therefore, atmospheric plasma technology can be applied very widely. The experiment was made using different proportions of ammonia(5%) /nitrogen mixture to generate plasma, and modify the surface of PLA. We expect to promote the biocompatibility by plasma generated nitrogen-based functional groups such as primary amino groups. The discharge was generated between two planar metal electrodes, with the both electrodes covered by quartz and the PLA sample was placed post-discharge region. At the beginning, plasma properties such as electrical, spectrum, temperature and chemical composition will be measured. To optimize the parameters as the experimental conditions. After plasma treatment, the contact angle changes from 82o to a minimum of 28o. N1s atomic ratio increase from 0% to 2.97%, it’s can be reach 5% with the increasing treatment times. The effect of plasma treatment on cell affinity of PLA surface was identified by observing the morphology through the culture of mouse C2C12 cells. Obviously, many cells attached to the surface of the modified PLA film and the cells stretched very well. Cells activity was grow stable in a long time observation. Compare with FTIR and XPS data, we might be known that primary amino functional groups(399.2 eV) are beneficial to cell adhesion. And how to get the optimize results by experimental control. Aging effect of plasma polymer are important, as marked changed to the surface chemistry of polymer may happen over the storage period. The detail of phenomenon will be described in this paper.