石墨烯高分子複合材料應用於電刺激藥物釋放及組織工程基材的製備

Abstract

電刺激治療在神經治療與組織修復扮演不可或缺的角色。本論文提供兩種電刺激藥物釋放，主要分成兩部分，第一部分是利用化學法合成的石墨烯（reduced graphene oxide, rGO）和聚乙烯醇poly（vinyl alcohol）(PVA)材料組成水膠做為電刺激藥物釋放系統研究。在藥物釋放的探討上，以疼痛藥物利多卡因(lidocaine hydrochloride)來做為藥物釋放的模擬藥物，研究水膠包覆釋放行為與機制，以應用於神經疼痛治療。實驗中證明加入還原已氧化的石墨烯於高分子水膠內可以改善機械性質與電性質及提升藥物包覆率，並製作成元件結構的型式來研究此水膠的自然藥物釋放以及電刺激持久型釋放與階段釋放的藥物釋放動力學結果。結果顯示此水膠經階段式電刺激，仍可保有高精確性與高重複性的藥物釋放行為，並且此rGO/PVA水膠具有生物相容性佳、易包覆親水性藥物，證明於此水膠未來可能應用於經皮輸藥系統或組織傷口修復。

第二部分，設計與製備電敏感性微膠囊(Microcapsule)作為藥物釋放載體，包覆神經生長因子，並排列微膠囊於透明導電基板上作為促進類神經細胞株大鼠腎上腺嗜鉻細胞瘤PC12增殖 (proliferation)與分化 (differentiation)之基材。實驗中改植接上-SH官能基的Poly(methacrylic acid) (PMA)以及石墨烯，利用氫鍵與雙硫鍵結吸附於無機多孔球核上形成結構穩定之球殼，觀察表面吸附球殼以及排列整齊之形貌，並用拉曼光譜與硫醇標準檢量線鑑定其合成。另外，本實驗也比較觀察在電場下與未施加電場時，rGOSH/PMASH微膠囊包覆生長因子之釋放行為分析，以及PC12細胞在此基材上的行為表現。由於我們設計高生物相容性及電性的層層交錯堆疊、包覆生長因子之化學誘導、電刺激誘導並控制rGOSH/PMASH微膠囊釋放生長因子，以及表面排列起伏(surface topography)之物理引導，可增強細胞存活率並增加分化細胞數目與突觸生長之長度，於培養一天後此基材的突觸生長長度相較於傳統玻璃基材可提高四倍，從實驗結果顯示皆有顯著性差異 (significant difference)。因此，未來將有希望可應用此新穎性rGOSH/PMASH微膠囊結構做為神經修復與神經再生之基材。

Electrical stimulated drug release has played an important role in the field of neurobiology. Our research provides two kinds of electrically controlled drug delivery systems. The first part of this study reported that hybrid hydrogel membranes composed of reduced graphene oxide (rGO) nanosheets and a poly (vinyl alcohol) (PVA) matrix. The rGO nanosheets in the matrix act as a physical barrier to inhibit the release of the model anesthetic drug, lidocaine hydrochloride, but the highly responsive release can be enhanced by the presence of rGO when exposed to an electrical stimulus. More interestingly, the on-demand drug release profiles of the assembling rGO/PVA hydrogel into a chip-like device can be highly controlled by an external electrical field. Release profiles ranging from a slow-elution pattern to a rapid release under electrical field treatment can be achieved by manipulating the rGO/PVA composition. Moreover, under cyclic exposure to the electrical stimulus, a highly controllable and repeatedly pulsatile release is obtained from the rGO/PVA hydrogel, implying that the hydrogel exhibits excellent anti-fatigue properties. By combining with the enhanced structural integrity and biocompatibility, the electrically responsive rGO/PVA hydrogel has demonstrated the potential biological applications in drug delivery system, transdermal therapy and wound healing. In the second part of this study, we designed the electrical sensitive rGOSH/PMASH LbL microcapsules encapsulated with nerve growth factor. We firstly functionalized thiol groups (-SH) onto the surface of rGO nanosheets and prepared the self-assembly rGOSH/PMASH LbL by hydrogen bonded multilayers that are cross-linked through disulfide (S-S) bonds onto the mesoporous silica microcapsules with versatility. The biocompatible and conductive rGOSH/PMASH microcapsules can be arrayed two-dimension onto transparent and conductive substrate to use as a scaffold for neuronal growth. The study focused on the NGF release behavior and controlled of neuron and rGOSH/PMASH microcapsule interfaces to manipulate neuronal development and neurite outgrowth. Under electric stimulation, the rGOSH/PMASH microcapsule stimulated the NGF releasing and accelerated the proliferation and differentiation of the PC12 cells. The average neurite lengths could enhance up to 85 um after culture on the rGOSH/PMASH microcapsule substrate for one day. The results suggested that the surface topography of arrayed rGOSH/PMASH microcapsule、NGF chemical cue and electrical stimulation increase the cell activities. We demonstrated that the rGOSH/PMASH microcapsules may be used as potential substrate for neural regeneration and neural prosthetics.