Abstract
摘要:生物體透過操控梯度機制來傳遞精確的生理訊息,這也維持著體內所有的蛋白質、細胞組織生長等等複雜功能。生物梯度的研究方法是在許多生物醫學研究學科,包括:組織工程,檢測診斷工程,和細胞/胚胎幹細胞研究,等等領域的新興趨勢。其研究範圍包括利用物理性質的梯度,例如,以梯度的方式去改變表面的可濕度、厚度、介電常數、溫度、表面拓譜形態等,以及化學成分組成的梯度改變。目前製作表面梯度的方法包括有:擴散法、微流體技術、生物印刷技術等,但這些方法在控制複雜的生物訊號時仍會受限,例如:無法精準的將化學梯度轉換成生物梯度,控制化學精度時卻缺乏了連續性,並且應用在不同基版材質時缺乏一個通則技術。
在本計畫中,我們將以化學氣相沉積(CVD)技術,製成具有梯度的官能化聚對二甲苯(poly-p-xylylene)共聚化合物塗層。這種聚合物塗層具有高度的生物相容性,並獲得美國食品藥物管理局(FDA)批准在多種植入性生醫裝置上的使用。更重要的是,此官能性鍍膜具備了獨特的化學反應官能基,可精確地用來固定其他生物分子。本計畫所提出的研究方法中,我們將利用本研究團隊獨特的雙向-化學氣相沉積 (two-sourced CVD) 設備來進行氣相分子共聚技術(copolymerization);並運用此技術在生物材料上,產生具有 (i)化學組成精度,(ii)連續性,以及(iii)梯度變化的表面化學訊息。我們將進行以下分析研究:
1. 計畫目標一:建立化學氣象沈積共聚法(CVD co-polymerization)製備梯度型鍍膜的最適化製程
• 化學氣相沉積共聚法是否能夠廣泛延伸利用在聚對二甲苯家族的其他成員並系統化製備具有不同官能機的梯度共聚物塗層?
• 單體進料的配比變化是否對等於共聚物梯度的組成比例?
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2. 計畫目標二:利用梯度型鍍膜鍵結固定生物分子後其分子密度與梯度濃度之組成關係
• 表面的官能基梯度(化學梯度)是否能精確進行反應並表現在鍵結固定後的生物分子梯度上?
• 鍵結固定後生物分子表面覆蓋率與梯度濃度之比例是否呈現一固定對應關係?
3. 計畫目標三:研究此表面梯度鍍膜對於細胞活動及生長導向的影響
• 細胞的生理活動是否能充分反映在此表面所傳遞的梯度訊息上?
• 固定後的生物分子梯度是否仍保有其應有的生物活性?
表面梯度鍍膜的研究成果將提供仿生工程技術一個重要的基礎研究工具,並且在組織工程、再生醫學和生物感測,等重要領域極具發展的潛力。
Abstract: Gradient-based approaches are an emerging trend in many biomedical research areas including tissue engineering, diagnostic research, and cell/embryonic assays. Major efforts have recently been devoted to generating gradients with gradual changes in physical properties such as wettability, thickness, dielectric constant, temperature, morphology and also gradients with continuously varied chemical composition. Although synthetic methods for producing these gradient surfaces such as bulk diffusion, microfluidic pathways, lithography, or a combination thereof showed preliminary promise, limitations remained for handling sophisticated biological signals and were often found to be lacking in the precise translation of chemical gradients into biological gradients, continuity in chemical resolution, and a general protocol for various substrates. In this proposed study, chemical vapor deposition (CVD) co-polymerization of substituted [2.2]paracyclophanes are used to prepare gradient coatings of functionalized poly(p-xylylene) copolymers. These polymer coatings have been shown to be biocompatible and are FDA approved in specific applications. More importantly, the polymer coating system that can accommodate reactive chemical groups in their structure, thus providing specific sites for covalent immobilization of biologic factors. We herein in this proposed study will exploit CVD copolymerization technology using a two-sourced CVD copolymerization installation, and develop an advanced gradient coating system that can deliver i) defined, ii) continuous, and iii) gradually-changed chemical composition over a biomaterial substrate.
This proposed work will be conducted with an existing CVD polymerization system in PI’s laboratory to achieve the following specific aims:
Aim #1: Establish missing specifications for the polymer gradients manufacturing process.
1. Can CVD copolymerization process be applied to a wide range of functional groups library and produce gradient copolymers?
2. Will a variation of monomer ratios result in defined gradient ratios?
Aim #2: Investigate the surface densities of immobilized biomolecules towards polymer gradients.
1. Can gradient coatings support the gradual immobilization of two different biomolecules?
2. Does the dependency of the surface coverages of the immobilized biomolecules valid towards the densities of the polymer gradients?
Aim #2: Demonstrate cellular transductional response towards polymer gradients.
1. Can cell physiological activities response to the biochemical information of the gradient surfaces
2. After dual immobilization, is the biological function with gradient information delivered??
The resulting gradient coatings can produce a fundamental tool in biomimetic researches with potential use in regenerative medicine, tissue engineering, and biological sensing applications.
Keyword(s)
生物梯度
表面改質技術
化學氣相沉積共聚技術
仿生工程技術
生物標記交聯技術
Gradients
Surface modification
Chemical vapor deposition (CVD) copolymerization
Biomimetic engineering
Bioconjugation