Nanotextured stainless steel for improved corrosion resistance and biological response in coronary stenting

Abstract

Nanosurface engineering of metallic substrates for improved cellular response is a persistent theme in biomaterials research. The need to improve the long term prognosis of commercially available stents has led us to adopt a 'polymer-free' approach which is cost effective and industrially scalable. In this study, 316L stainless steel substrates were surface modified by hydrothermal treatment in alkaline pH, with and without the addition of a chromium precursor, to generate a well adherent uniform nanotopography. The modified surfaces showed improved hemocompatibility and augmented endothelialization, while hindering the proliferation of smooth muscle cells. Moreover, they also exhibited superior material properties like corrosion resistance, surface integrity and reduced metal ion leaching. The combination of improved corrosion resistance and selective vascular cell viability provided by nanomodification can be successfully utilized to offer a cell-friendly solution to the inherent limitations pertinent to bare metallic stents.

Stable Titania Nanostructures on Stainless Steel Coronary Stent Surface for Enhanced Corrosion Resistance and Endothelialization

“…In this paper, we present a novel approach to nanotexture the stent surface to concurrently enable enhanced endothelialization and reduced smooth muscle cell proliferation. Previous works by our group as well as others have shown the beneficial effects of nano‐topographical modifications of metals, mainly titanium, in regulating cellular behavior . Our research demonstrated stable and uniform nanotextured titania surface on metallic Ti through a facile hydrothermal processing technique that exhibited excellent vascular cell response and hemocompatibility in vitro .…”

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

“…14 Our results also correspond to other studies evaluating the effects of nanostructure on in vitro hemolysis, in which low roughness nanoscale topographies (of titanium and 316 L stainless steel) did not induce hemolysis under static and/or dynamic conditions. 26,27 Although the NCD coatings in this study did not demonstrate hemolytic effects, some studies have reported hemolysis as well as RBC penetration and an effect on RBC oxygenation function in blood exposed to discrete nanodiamond particles. Adverse responses to nanodiamond particles should be considered for NCD coatings due to the potential of nanoparticulate wear debris.…”

“…These results are consistent with the literature in which carbon‐based coatings exhibited no hemolytic response . Our results also correspond to other studies evaluating the effects of nanostructure on in vitro hemolysis, in which low roughness nanoscale topographies (of titanium and 316 L stainless steel) did not induce hemolysis under static and/or dynamic conditions …”

“…Previous studies on the effects of nanotopography on blood coagulation have shown that plasma incubated on nanostructured surfaces exhibited significantly longer clotting times (PT, APTT, and TT) under dynamic flow conditions compared to control surfaces for titania and similar clotting times as control surfaces under static conditions for stainless steel . For titania, plasma incubated on nanostructures with larger feature sizes (135 nm) exhibited longer clotting times with aPTT compared to the nanostructures with smaller feature sizes (55 nm), though the difference in oxide layer thickness may have influenced the response …”

“…Previous studies on the effects of nanotopography on hemocompatibility of other biomaterials (e.g., titanium/titania, alumina, stainless steel, gold, and polymers) have demonstrated that blood cell and platelet responses are strongly influenced by the surface topography characteristics. [23][24][25][26][27][28][29][30] Furthermore, while some studies have shown that nanoscale surface topographies have minimal to no effects on blood responses, 31,32 other studies suggest that surface topography in the submicron and nanoscale range can modulate platelet adhesion, 23,24,29,30,[33][34][35] platelet aggregation, 34 platelet activation, 23,24,26,29,30 platelet microparticle generation, 24,25,29 complement activation, 29 coagulation, 26 and thrombosis. 26 Therefore, to investigate the hemocompatibility of NCD coatings for cardiovascular device applications, it is critical to evaluate the effects of different NCD surface nanotopographies on blood-material interactions.…”