Bioengineering Graduate Program, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
J Biomed Mater Res A. 2013 Mar;101(3):622-32. doi: 10.1002/jbm.a.34361. Epub 2012 Aug 28.
This study systematically investigated the effects of microtopographic patterns of titanium oxide on platelet adhesion and activation in order to reveal the mechanisms of interactions between platelet and surface topography. Periodic arrays of groove and pillar patterns with dimensions ranging from submicron to several micrometers were fabricated by photolithography and deep reactive-ion etching on silicon substrates, followed by the sputter deposition of titanium oxide (TiO(2)). Platelet adhesion and activation on TiO(2) patterned surfaces were evaluated by lactate dehydrogenase (LDH) and GMP-140 assays, respectively. The morphology of adherent platelets was examined by scanning electron microscope (SEM). The results showed that the microtopographic patterns were able to effectively manipulate the platelet response by varying geometry and size of patterns. A groove pattern resulted in much higher levels of platelet adhesion and activation than a pillar pattern. The study revealed that a difference in pattern size led to two distinctive modes of platelet adhesion: the "bridging" mode in which platelets can bridge over spacing between adjacent patterns when spacing size is smaller than 1.5 μm; and the "full-contact" mode in which platelets cannot bridge but fully contact the entire surface when spacing size is larger than 3 μm. Our analysis indicates good correlations between platelet behavior and hydrophobicity/wetting anisotropy in "bridging" mode, and effective surface contact area in "full-contact" mode.
本研究系统地研究了氧化钛的微观形貌对血小板黏附和激活的影响，以揭示血小板与表面形貌相互作用的机制。通过光刻和深反应离子刻蚀在硅衬底上制备了从亚微米到几微米尺寸的周期性沟槽和立柱图案，然后通过溅射沉积氧化钛（TiO2）。通过乳酸脱氢酶（LDH）和 GMP-140 测定法分别评估了 TiO2 图案表面上的血小板黏附和激活。通过扫描电子显微镜（SEM）检查了黏附的血小板的形态。结果表明，通过改变图案的几何形状和尺寸，可以有效地操纵血小板的反应。沟槽图案导致的血小板黏附和激活水平明显高于立柱图案。该研究揭示了图案尺寸的差异导致了两种截然不同的血小板黏附模式：当间隔尺寸小于 1.5μm 时，血小板可以在相邻图案之间的间隔处“桥接”；当间隔尺寸大于 3μm 时，血小板不能桥接，但可以与整个表面完全接触。我们的分析表明，在“桥接”模式下，血小板行为与疏水性/润湿性各向异性之间存在良好的相关性，而在“完全接触”模式下，有效表面接触面积与血小板行为之间存在良好的相关性。
