近年來許多學者投入研發生醫材料想關研究，希望能夠造福更多病患，由於材料置入於生物體時，其表面會和體內細胞環境互相接觸，因此表面性質扮演著重要的角色，而表面和細胞間的作用力相當重要，如臨床上用於骨科生醫材料上，希望材料能有很好的骨整合能力，因此細胞貼附於表面的能力相當重要，細胞要能夠貼附於表面才能夠發揮其功能。因此我們希望以長碳鏈硫醇在金表面形成自組裝單分子層(self-assembled monolayers, SAMs)做為平台來研究類骨細胞於表面生長情形。
為了增加材料的生物相容性，我們藉由仿生的概念仿照細胞膜含有雙電性分子，希望製備出含有雙電性的表面，此外我們引入兩個不同解離強度的官能基亞磷酸根phosphate group(-PO3H2)、磺酸根sulfate group(-SO3H)官能基來製備表面，為了達到具有雙電性的表面，我們引入文獻中鮮少人使用的強迫帶正電親水性的-N+(CH3)3烷基硫醇和-SO3H、-PO3H2烷基硫醇形成混合雙電性自組裝單分子層-N+(CH3)3 & -SO3H mixed SAM、-N+(CH3)3 & -PO3H2 mixed SAM，希望能夠了解雙電性分子和細胞間的交互作用以及不同解離強度的帶負電官能基和帶正電官能基所製備出的表面對細胞貼附增生的影響。
結果顯示混合雙電性-N+(CH3)3& -SO3H mixed SAM ，其XN(CH3)3,soln= 0.3、0.5、0.7都不利於細胞增生，但細胞於-N+(CH3)3-SAM、-SO3H-SAM表面培養七天後卻都有良好的細胞貼附現象並且有多量的細胞增生的現象，雖然有些試片有利於細胞增生的現象但卻沒有促進細胞分化的現象；混合雙電性-N+(CH3)3 & -PO3H2 mixed SAM，不論XN(CH3)3,soln=0、 0.3、0.5、0.7、1，都能有良好的細胞增生表現，但也都沒有促進細胞分化的現象，不過本研究還發現了一個有趣的現象，文獻上鮮少用來形成自組裝單分子層的-N+(CH3)3-SAM於短時間不利於細胞貼附，但經過長時間的培養卻能有良好的細胞增生貼附現象產生。

The interactions between the surface of artificial biomaterial and biological environment are considered to be the important factors that affect its biocompatibility and clinical effectiveness. For example, the osteointegration is an important step for the success of a hip arthoplasty. Thus, adhesion of cells to biomaterials surface followed by proliferation and differentiation is a prerequisite for a success biomaterial. In this investigation, we have utilized self-assembled monolayer technique for the preparation of a model surface with an aim to study the interactions between the material and physiological environment, especially the cells, easily.
Since the cell membrane contains the zwitterionic structure, a biomimic zwitterionic surface prepared by mixed cationic and anionic terminated alkanethiols was utilized in order to improve the surface biocompatibility. Previous studies have shown that the phosphate(-PO3H2)、sulfonic acid (-SO3H) functionality would affect the proliferation of osteoblast-like cell. Henceforth, these two alkanethiols having terminal ends with different acidic dissociation constant were utilized for preparing zwitterionic SAMs by mixing with cationic trimethyl amine terminated alkanethiol. The cell contacting characteristics on these two series of mixed zwitterionic SAMs were explored in this investigation.
The results showed that the zwitterionic-N+(CH3)3 & -SO3H mixed SAM (XN(CH3)3,soln= 0.3、0.5、0.7) are poor surface for cell proliferation while the pure -N+(CH3)3 and -SO3H terminated SAM showed great cell proliferation after seven days culture. In contrast, for the zwitterionic-N+(CH3)3 & -PO3H2 mixed SAM, the cell proliferated well on all surfaces (XN(CH3)3,soln=0、 0.3、0.5、0.7、1) after a long time culture. ALP assays indicated that neither of these two series of mixed zwitterionic SAMs improved the cell differentiation. Moreover, the cell live/dead assay has indicated that the pure -N+(CH3)3 terminated SAM surface could lead to cell death after contacting with cells for a short period. However, after a long term contacting, the cells adhered become proliferated well.

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