當周邊神經受損時，若未進行適當處理，神經斷裂處的軸突會產生分岔導致斷端神經失去功能。而若經適當處理，神經細胞的軸突卻有可能從斷裂的近端穿越神經受損區段，重新連接斷端兩側的神經使功能恢復。近年來，組織工程技術為周邊神經再生的主要研究重點。可吸收性聚乳酸做為組織用支架而利於神經再生功能，已受到相當的注意。因其適當的機械強度、可塑性、分解周期等特性，聚乳酸常用於神經再生導管的結構材料。本研究以聚乳酸為基材，將表面形成化學與構型的修飾，以引導貼附細胞產生定向、定域的生長。
首先，以熱壓印的方式於聚乳酸模板上製成微溝構型，再濺鍍金粒子於微溝槽的底面。之後，利用微接觸壓印技術形成兩個化學修飾的表面，亦即將ODT (Octadecanethiol)自組裝單分子層接枝於間壁表面；而溝槽內部則接枝RGD氨基酸序列。前者可阻止細胞橫越間壁而不互相跨越，後者可形成促進細胞貼附的表面。藉此，細胞可被引導並沿著微溝槽生長。
由X光光電子能譜分析結果顯示：RGD及ODT分子可經微接觸壓印，成功地接在鍍金之聚乳酸構型模板上。而由許旺細胞的細胞貼附於化學修飾之鍍金聚乳酸模板上的形態及數目也顯示：RGD修飾的表面，其誘導細胞貼附數量高於聚乳酸模板表面約2.14倍，且使許旺細胞呈固定貼附；而ODT自組裝單分子形成的疏水性表層上能抑制細胞貼附。整體而言，藉由RGD氨基酸、疏水性ODT分子、及微溝構型的組合，可使許旺細胞貼附於RGD氨基酸表面，並調適其延伸方向。未來可針對不同區域之組織支架進行修飾與構型，以誘導或抑制細胞貼附，並進一步控制神經的定向生長。
關鍵字：聚乳酸、微溝槽、RGD氨基酸序列、ODT自組裝單分子層、微觸壓印、許旺細胞。

When the peripheral nerve wounded, nerve injuries complicate successful rehabilitation, because mature neurons do not replicate. Under right conditions, however, axon extensions can be occurred over gaps by reconnecting with the distal stump and reestablishing functional contact. Peripheral nerve injury that results in long gaps requires surgical implantation through a bridge with guidance channels to restore full function of neuron. In recent years, tissue engineering intending to regenerate peripheral nerves has been developed into a major research topic.

Bioadsorbable poly-L-lactic acid (PLLA) used as a functional scaffold for nerve regeneration have paid much attention. Because of its proper characteristic in mechanical property, plasticity and degradation period, PLLA is commonly applied as a scaffold material for nerve conduit. In this study, PLLA was used as the base substrate and then structured with chemical and topographical modifications. Along a specific route, the adhered cells can be guided with directional growth.

Firstly, PLLA film was patterned with microgrooves by hot embossing and then the as-patterned surface was coated with Au. Subsequently, two distinct chemically-stimulated surfaces, namely, thiol-modified arginine- glycine- aspartic (RGD) along the microgrooves and hydrophobic octadecanethiol (ODT) self-assembly monolayers between the microgrooves, were respectively created by micro-contact imprint. For the former, it might inhibit the cells from crossing over the micro-grooves; for the latter, it might promote cells attachment. As a consequence, the cells were presumably guided and competent to grow along the micro-grooves.

Experimental results from HRXPS demonstrated that RGD peptides and ODT molecules were successfully immobilized on Au-coated and micro-patterned PLLA by micro-contact printing. From the morphologies and quantity of adhered Schwann cells on the modified Au-coated PLLA surfaces, the results exhibited that the cells firmly attached on the RGD-modified surface and increased 2.14 times as compared with those on the patterned PLLA surface. On the other hand, the ODT-modified Au-coated PLLA surface was competent to prevent Schwann cells from anchoring on the surface. In summary, Schwann cells adhesion and their outgrowth direction were greatly regulated by the combination of RGD peptides, hydrophobic ODT molecules, and topographical microgrooves. It is therefore promising to modify and arrange a select region of tissue scaffolds to induce or inhibit cells attachment and furthermore to control the outgrowth of nerve cells.

Keywords: poly-L-lactic acid, micro-grooves, RGD peptide, ODT molecules, micro-contact imprint, Schwann cells.

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