- 學位論文
藉由石英振盪微天平觀察細菌於不同親疏水性之自組裝單層膜表面之貼附行為
Quartz Crystal Microbalance with Dissipation (QCM-D) Study of Bacterial Attachment Process on Surfaces of Different Hydrophilicity
摘要
金黃色葡萄球菌(Staphylococcus aureus)存在於環境或人體中，時常造成人類罹患疾病甚至死亡。細菌常藉由分泌胞外聚合物(Extracellular Polymeric Substance, EPS)形成生物膜幫助貼附於生物體或非生物體並加速繁殖及感染。本研究利用自組裝單層膜(Self-assembled monolayer, SAM)技術建構一系列不同親疏水性的表面，利用搭配偵測能量消散功能的石英振盪微天平(Quartz Crystal Microbalance with Dissipation monitoring, QCM-D)欲探討金黃色葡萄球菌於不同表面的生長情形。希望能藉由了解細菌貼附的機制，找到適合抗菌的表面。 本研究的結果顯示，利用配製不同比例的1H, 1H, 2H, 2H-全氟辛硫醇(1H, 1H, 2H, 2H-perfluoro-1-octanethiol)以及8-羥基-1-辛烷硫醇 (8-mercapto-1-octanol)溶液可使自組裝單層膜成長於金基材表面，表面的接觸角介於110°至21°之間，且表面親疏水性可由吾人任意調控。 金黃色葡萄球菌貼附於表面會經過數個階段完成貼附行為。在過程中，QCM-D觀察到細菌於疏水表面的貼附行為使所有泛頻頻率下降。相對地，細菌於親水表面的貼附行為則使基頻與低泛頻產生耦合震盪效應，使共振頻率上升。這可能是來自細菌會分泌EPS幫助貼附於表面所致；隨著表面疏水性增加，黏附於表面的EPS越多。根據QCM-D各泛頻的漸逝波穿透深度可知，於親水表面所吸附的EPS厚度約為112 nm 至 144 nm之間，而疏水表面的EPS層厚度則高於250 nm。
並列摘要
Bacteria can sense interfacial properties and secret bacterial extracellular matrix (ECM) as a biofilm to protect them from hostile environments. The formation of biofilm is also an important cue to understand the disease causing. Therefore, the ability to control biofilm formation and studying the effect of surface properties can reveal how bacteria interact with the surface and tailor its behaviors. Self-assembled monolayers (SAMs) are known for its versatility and convenience to modify surface. In previous work, serial surface property can be achieved by introducing two kinds of functional groups in different ratios. In this study, serial hydrophilicity surfaces were achieved by applying 1H, 1H, 2H, 2H-perfluoro-1-octanethiol and 8-mercapto-1-octanol that provide hydrophobic –CF3 and hydrophilic –OH surface functionalization, respectively, in different ratios on gold surfaces. The composition on the surfaces was measured by X-ray photoelectron spectroscopy (XPS) and the water contact angle varied from 110° to 21°. These SAM-Au coated quartz sensors were then used in a quartz crystal microbalance with dissipation monitor (QCM-D) to investigate near-surface viscoelastic changes between Staphylococcus aureus and serial hydrophilicity surfaces by recording shift in resonant frequency (Δf) and energy dissipation (ΔD) during 15 h incubation. The QCM data showed that the attachment can divide into several stages. Bacteria on the hydrophobic surface leaded to the drop of resonance frequency. On the other hand, bacteria on hydrophilic surface had coupled oscillation that make fundamental frequency and low overtones have positive shift. The difference might be caused by the amount of EPS deposited on the surface. On the hydrophilic surface, the amount of EPS attaching on the surface was few. However, with the increase of the hydrophobicity, EPS was more easily attaching on the surface. According to the depth of evanescent wave, EPS layer on the hydrophilic surface was about 112 nm - 144 nm, and the EPS layer on the hydrophobic surface was more than 250 nm.
參考文獻
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