title: Effects of microtopographic patterns on platelet adhesion and activation on titanium oxide surfaces.
abstract: 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.
authors.affiliation: Bioengineering Graduate Program, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Ding
authors.forename: Yang
authors.initials: Y
authors.lastname: Leng
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.forename: Xiong
authors.initials: X
authors.lastname: Lu
authors.forename: Xiang
authors.initials: X
authors.lastname: Ge
authors.forename: Fuzeng
authors.initials: F
authors.lastname: Ren
authors.forename: Kefeng
authors.initials: K
authors.lastname: Wang
authors.forename: Lijuan
authors.initials: L
authors.lastname: Lei
authors.forename: Xiang
authors.initials: X
authors.lastname: Guo
mesh_terms: D001792:Blood Platelets / Q000201:enzymology* / Q000648:ultrastructure; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010973:Platelet Adhesiveness; D014025:Titanium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; C009495:titanium dioxide; D014025:Titanium; D007770:L-Lactate Dehydrogenase