鈦-六鋁-四釩之不同拋光製程對表面生物膜性質的影響

近年來，Ti-6Al-4V ELI合金被廣泛應用於生醫材料與牙科植體領域；就牙科植體應用而言，口腔牙科植體周圍仍會因細菌堆積，引發植體周圍炎，造成骨流失，最終導致植牙失敗。因此，本論文主要目的：探討不同表面拋光與熱處理製程，形成不同粗糙度與顯微結構的表面，分析其表面特徵，包括：接觸角、氧化膜(含氧含量)等；進一步，研究其對細菌附著量的影響，包括：菌落數計算(CFU/mL)、細菌附著量濃度(OD)等。本論文透過機械拋光、化學拋光、電解拋光，利用原子力顯微鏡與雷射共軛聚焦顯微鏡，觀察Ti-6Al-4V ELI合金表面之不同表面粗糙度；且利用掃描式電子顯微鏡、液滴法、X射線光電子能譜學、X射線繞射儀等技術，分析合金之接觸角、氧含量與顯微結構。同時，使用口腔鏈球菌進行細菌附著量實驗，採用平板計數法計算菌落數與結晶紫染色測量其吸光值，最後使用SPSS 20.0進行統計分析實驗結果。商用Ti-6Al-4V ELI合金，顯微結構為α相基地+12%島狀β相組織。經不同拋光處理後，合金之巨觀與微觀粗糙度，分別介於0.68 μm~2.34 μm與10.33 nm~120.05 nm之間。接觸角分析顯示：研磨方向與垂直研磨方向之接觸角，分別介於21.38°~96.44°與18.37°~92.72°之間。此外，根據XPS分析數據，則顯示：合金表層0 nm~20 nm之間，存在高氧特徵；XRD分析，則顯示：表面存在有TiO2結構之組織。其間，表面氧含量介於66.06 a.t.%~79.54 a.t.%之間。生物膜研究，則顯示：變形鏈球菌之菌落數介於(7.87~17.73)×106 CFU / mL之間；吸光值介於0.189~0.245之間。此外，Ti-6Al-4V ELI合金經800℃、920℃、960℃與1040℃熱處理後，其顯微結構分別為：α相基地+18%島狀β相組織、α相+63%β相組織、α相+78%β相(α’)組織、以及β相(α’)組織；其間，α’相具針狀組織結構，係為高溫β相經麻田散體相變態之組織。經機械拋光處理後，合金之微觀粗糙度，分別介於21.10 nm~72.89 nm、34.23 nm~124.62 nm、33.33 nm~67.40 nm與25.58 nm~78.80 nm之間。接觸角，則分別介於23.39°~54.66°、32.17°~72.90°、35.53°~68.30°與37.78°~79.87°之間。生物膜研究，則顯示：變形鏈球菌之菌落數分別(2.90~8.10)×106 CFU/mL、(2.91~29.03)×106 CFU/mL、(2.07~14.40)×106 CFU/mL與 (1.76~7.23)×106 CFU/mL之間；吸光值則介於0.133~0.167、0.120~0.143、0.140~0.173與0.113~0.160之間。結論，合金之表面粗糙度與細菌附著量呈現正相關；而，表面接觸角與氧含量，則與細菌附著量呈現負相關。另外，細菌附著量特徵，與合金之顯微組織存在相關性；隨著，合金之β相(α’)組織比例上升，呈現負相關。

關鍵字

拋光； Ti-6Al-4V ELI ；粗糙度；接觸角；氧含量；生物膜；細菌

並列摘要

Recently, Ti-6Al-4V ELI alloy has been widely used to biomaterials and dental implants. However, bacterial accumulation around the dental implants in the oral cavity cause inflammation and bone loss. The implant would be failure finally. Therefore, the main purpose of this thsis is investigating different surface polishing and heat treatment processes to form surfaces with different roughness and microstructure are analyzed the surface characteristics, including contact angle, oxide film (oxygen content) and effect of bacterial adhesion such as colony count calculation (CFU/mL), bacterial adhesion concentration (OD). The Ti-6Al-4V ELI of present study after mechanical polishing, chemical polishing and electropolishing were analyzed surface roughness via atomic force microscope and laser conjugate focusing microscope. The contact angle, oxygen content, surface topography and microstructure of alloys were analzed via drop method, X-ray Photoelectron spectroscopy, X-ray diffractometer and scanning electron microscope. In addition, the bacterial adhesion experiment using Streptococcus mutans to quantify the number of colonies and optical density value via plate counting method and crystal violet staining. Finally, the study carried out statistical analysis by SPSS 20.0. Based on the present studies, it reveals that: (1)the microstructure of Ti-6Al-4V ELI alloy is a α-phase matrix with 12% island β-phase particles structure. After different polishing, the macroscopic and microscopic roughness of the alloy are in a range of 0.68~2.34 μm and 10.33~120.05 nm, respectively. The contact angle of the grinding direction and the vertical grinding direction were in a range of 21.38°~96.44° and 18.37°~92.72°. In addition, it is shown that high oxygen characteristics on surface of the present alloy. Moreover, the surface oxygen content is in a range of 66.06 a.t.% and 79.54 a.t.%. Accorrding to the XRD analysis, it also shows that some TiO2 structure occurred on the surface. Results of bacterial adheison showed that the number of colonies of Streptococcus mutans is in a range of (7.87-17.73)×106 CFU/mL and the optical density value is in a range of 0.189 and 0.245. In addition, being heated at 800℃, 920℃, 960℃ and 1040℃ the microstructures of present alloy were α-phase matrix with 18% island β-phase particle, α-phase matrix with 63% α'-phase particle, α-phase matrix with 78% α'-phase particle, full α'-phase particle, of which α'-phase belongs to the needle-like structure formed during cooling processes. After mechanical polishing, the micro roughness of the alloys are in a range of 21.10~72.89 nm, 34.23~124.62 nm, 33.33~67.40 nm, and 25.58~78.80 nm, respectively. The contact angles are in a range of 23.39°~54.66°, 32.17°~72.90°, 35.53°~68.30° and 37.78°~79.87°, respectively. Meanwhile, the resluts of bacterial adhesion showed that the colony numbers of Streptococcus mutans were in a range of (2.90~8.10)×106, (2.91~29.03)×106, (2.07~14.40)×106 and (1.76~ 7.23)×106 CFU/mL, respectively; and, the optical density being in a range of 0.133~0.167, 0.120~0.143, 0.140~0.173 and 0.113~0.160, respectively. Conclusion, the surface roughness and the amount of bacterial adhesion are positive correlation; the surface contact angle and oxygen content are negatively correlated with the amount of bacteria attached. It shows that the amount of bacterial adhesion decreases as well as the beta phase (α') structure increased.