Bioengineering cobalt chromium cardiovascular stent biomaterial for
surface enhancement and characterization
Cobalt Chromium alloy L605 is an underlying biomaterial for most new
generation drug eluting stents (DES) and bare metal stents (BMS).
Suboptimal biocompatibility of stents clinically manifest as thrombosis
and restenosis. We optimized a plasma-activated coating (PAC)
technology to modify alloy L605 material surface (PAC-L605), for the
first time, for enhanced biocompatibility. This study details in vitro
characterization to identify and optimize the physical, chemical, and
mechanical properties of the modified material surface PAC-L605.
Surface hydrophilicity characterized post-modification with water
contact angle and plasma kinetics, showed improved hydrophilicity for
PAC-L605. Surface chemistry of PAC-L605 vs. L605, quantified with energy
dispersive x-ray spectroscopy (EDS), showed comparatively higher weight
percent of carbon and nitrogen on PAC surfaces. The microscale,
isotropic surface roughness of PAC-L605, was computed with NanoMap white
light interferometry (WLI). Surface stiffness computed via
nanoindentation at minimum compression load 0.19 mN - increasing to
maximum load 50 mN, showed similar stiffness for PAC-L605 and L605 at
higher load. Nanoindentation results confirmed robust adhesion of PAC to
L605, and unique non-delaminating character of PAC under compression.
Furthermore, surface modification at PAC-L605 interface was visualized
via high-resolution transmission electron microscopy (HRTEM).
Improvements of surface character for implantable cardiovascular
materials could be achieved by plasma-activated coating (PAC). Optimal
surface modifications may trigger desirable biological responses in
vitro and in vivo.