當植入物與血液接觸後，會吸引血液中的血漿蛋白貼附，進而誘發血小板的活化而導致血管栓塞，目前接受血管支架手術的病人，在術後必須長期服用兩種以上的抗凝血藥，其藥物不僅對人體造成副作用外，同時也會對患者的生活帶來不便性由於。為了減少藥物伴隨的副作用，植入物的表面必須要具備有良好抗積垢(Anti-fouling)的效果，來提升植入物的血液相容性。
先前的文獻已證實，雙電性離子具有極佳的抗積垢能力，其結構同時具有陽離子與陰離子，但本身仍保持電中性，因此可藉由靜電吸引力在材料表面形成水合層，以達到抗積垢效果。本實驗受到臨岸生物貝類淡菜(Mussel)啟發，淡菜能夠分泌含胺基鄰苯二酚結構的胺基酸3,4-dihydroxylphenyl-L-alanine (DOPA)並黏附在各種無機、有機材質表面。同樣多巴胺也同樣具有含胺基鄰苯二酚結構，能夠做為錨定基團(Anchor group)應用在各式各樣的基材表面。
本研究將結合上述特性合成出單一分子同時具有雙電性與含胺基鄰苯二酚官能基的新穎結構(全名, CB-DA)，CB與文獻使用的SB相比具有不受外界環境參數變化所影響，CB-DA將會應用在鈦金屬，評估在表面改質可行性。之後針對常用於血管支架材料的鈦金屬進行抗細菌貼附與生物相容性測試。

At present, the patients must take two or above kinds of anticoagulant medicines for long term after undergoing intravascular stent angioplasty. Because when direct contact of implant stent interface with blood accompanies nonspecific protein adsorption, which will induce adverse pathogenic problems, such as tissue adhesion, thrombosis and infection. In order to solve the critical issue, anti-fouling (i.e. protein and/or microorganism adsorption resistant) properties are desperately needed for an implant devices.
Many researcher have shown that the zwitterionic structure is the best anti-fouling materials, because it has both cationic and anionic functionality and can attract water molecular to form hydration layer by electrostatic force. Such a hydration layer can resist protein and microbial attachment. Our lab is inspired by mussels through their byssal threads generate the proteins full of the specific amino acid — DOPA which contains amine and catechol structure, it can strong attach virtually all types of inorganic and organic surfaces. Dopamine structure has similarly amine and catechol structure, it is usually used to surface modification of different substrates.
In this study, our lab wants to combine two properties above to synthesize an unprecedentedly compound containing both zwitterionic carboxybetaine and catechol functionalities — carboxybetaine dopamine(CB-DA). CB-DA will apply to titanium for surface modification, and we will assess its feasibility on surface modification. Afterwards, we will choose titanium, which is the most used materials for stent, to do anti-biomolecule adhesion, cell cytotoxicity test, to prove after grafting substrates render surfaces will enhance anti-fouling performance.

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