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.

Cooperative control of blood compatibility and re-endothelialization by immobilized heparin and substrate topography

“…The protocol used to evaluate platelet adhesion is described in our previous report [28]. Briefly, to prepare platelet-rich plasma (PRP), whole blood was centrifuged (200g, 15 min) and the supernatant was collected.…”

Effects of nanotopography on the in vitro hemocompatibility of nanocrystalline diamond coatings

“…Our results show no significant differences in platelet responses (adhesion, aggregation, and activation) on NCD coatings with small grain sizes versus large grain sizes. The importance of considering nanotopography in hemocompatibility is highlighted by previous studies that have shown platelet responses are dependent on multiple surface topography characteristics, including surface feature size, 23,24,30,69,70 geometry, 69 aspect ratio, 23 density, 23,30 and roughness of the biomaterial surface. 29,69,71 NCD is an ideal biomaterial coating for blood-contacting devices due to its mechanical robustness, chemical inertness, high wear resistance, and biocompatibility.…”

“…The importance of considering nanotopography in hemocompatibility is highlighted by previous studies that have shown platelet responses are dependent on multiple surface topography characteristics, including surface feature size, 23,24,30,69,70 geometry, 69 aspect ratio, 23 density, 23,30 and roughness of the biomaterial surface. 29,69,71 NCD is an ideal biomaterial coating for blood-contacting devices due to its mechanical robustness, chemical inertness, high wear resistance, and biocompatibility. 15,16,32,72 In this study, NCD coatings with different nanoscale grain sizes were successfully fabricated in a controllable and reproducible manner.…”

Real‐Time Visualization of Platelet Interaction With Micro Structured Surfaces

“…Ding et al. investigated titanium oxide pillars as well as grooves statically with human platelet‐rich plasma (PRP) for 45 and 60 min, respectively, in terms of activation and adhesion. After scanning electron microscopy (SEM), they concluded that structure distances should be within a range of 1.5–3 μm to avoid “bridging” between the structures and at the same time full contact of platelets to the surface.…”

“…The chemical methods include all modifications of the material's chemistry as, for example, organic and inorganic coatings or bio-functionalization (9)(10)(11)(12)(13). Physical methods include all techniques which alter the surface properties by mechanical structuring of the surfaces, for example, random or regular structures in the micro-or nanometer range or the adjustment of a special roughness (3,7,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). Ding et al…”