The objective of this study was to evaluate the biocompatibility of trimethylsilane (TMS) plasma nanocoatings modified with NH₃/O₂ (2:1 molar ratio) plasma post-treatment onto cobalt chromium (CoCr) L605 alloy coupons and stents for cardiovascular stent applications. Biocompatibility of plasma nanocoatings was evaluated by coating adhesion, corrosion behavior, ion releasing, cytotoxicity, and cell proliferation. Surface chemistry and wettability were studied to understand effects of surface properties on biocompatibility. Results show that NH₃/O₂ post-treated TMS plasma nanocoatings are hydrophilic with water contact angle of 48.5° and have a typical surface composition of O (39.39 at.%), Si (31.92 at.%), C (24.12 at.%), and N (2.77 at.%). The plasma nanocoatings were conformal to substrate surface topography and had excellent adhesion to the alloy substrates, as assessed by tape test (ASTM D3359), and showed no cracking or peeling off L605 stent surfaces after dilation. The plasma nanocoatings also improve the corrosion resistance of CoCr L605 alloy by increasing corrosion potential and decreasing corrosion rates with no pitting corrosion and no mineral adsorption layer. Ion releasing test revealed that Co, Cr, and Ni ion concentrations were reduced by 64–79%, 67–69%, and 57–72%, respectively, in the plasma-nanocoated L605 samples as compared to uncoated L605 control samples. The plasma nanocoatings showed no sign of cytotoxicity from the test results according to ISO 10993-05 and 10993-12. Seven-day cell culture demonstrated that, in comparison with the uncoated L605 control surfaces, the plasma nanocoating surfaces showed 62 ± 7.3% decrease in porcine coronary artery smooth muscle cells (PCASMCs) density and had comparable density of porcine coronary artery endothelial cells (PCAECs). These results suggest that TMS plasma nanocoatings with NH₃/O₂ plasma post-treatment possess the desired biocompatibility for stent applications and support the hypothesis that nanocoated stents could be very effective for in-stent restenosis prevention.

Zirconia restoration debonding is one of the common issues in its dental applications because of its dense and chemically inert structure that is difficult to bond to. In this study, plasma treatment of zirconia was performed to improve its bond strength and longevity with dental resin cement. Sandblasted zirconia specimens were treated using argon cold atmospheric plasmas (CAPs), followed by applying a thin layer of 10-MDP primer, dental resin cement with light curing. Micro-shear bond strength (µSBS) test results showed that 300 s of CAP treatment significantly increased the initial µSBS to 38.3 ± 5.6 MPa as compared with the 21.6 ± 7.9 MPa without CAP treatment. After 30 days of storage in 37 °C deionized (DI) water, CAP-treated zirconia specimens had 191.2% higher bond strength than the bonded specimens without plasma treatment. After 1000 cycles of thermal cycling (TC) between 5 °C and 55 °C, the CAP-treated zirconia specimens gave 30.5% higher bond strength than the bonded specimens without plasma treatment. Surface–water contact angle measurements indicated that the zirconia surface became much more hydrophilic but showed rapid hydrophobic recovery within the first hour of CAP treatment, indicating the importance of promptly applying the primer after the plasma treatment. These findings suggest that the argon CAP technique is effective in the surface preparation of zirconia for enhancing bond strength and longevity with dental cement.

The objective of this study was to evaluate the coating integrity performance and corrosion protection property of trimethylsilane (TMS) plasma nanocoatings that were directly deposited onto cobalt chromium (CoCr) L605 cardiovascular stents. Hydrophilic surfaces were achieved for the TMS plasma nanocoatings that were deposited onto the coronary stents through NH₃/O₂ (2:1 molar ratio) plasma post-treatment. With a coating thickness of approximately 20–25 nm, the TMS plasma nanocoatings were highly durable and able to resist delamination and cracking from crimping and expansion by a Model CX with a J-Crimp Station. The stent surface that was evaluated by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) showed no indications of pitting, corrosion, or adsorption products on either the luminal or abluminal surfaces of the stents, in contrast to the uncoated stent surface. The TMS plasma nanocoatings significantly enhanced the stent’s corrosion resistance in immersion experiments that followed the ASTM F2129-15 corrosion protocol, evident in the increase of the open circuit potential (OCP) from 0.01 V for the uncoated L605 stent to 0.18 V for the plasma-nanocoated L605 stent, reducing potential cytotoxic metal ion release. Cyclic polarization (CP) curves show that the corrosion rate (density level) observed in plasma-nanocoated L605 stents was approximately half an order of magnitude lower than that of the uncoated stents, indicating improved corrosion protection of the stents. CP curves of the TMS plasma-nanocoated stents with different coating thicknesses show that, in the range of 20–65 nm, the coating thickness does not result in any difference in the corrosion resistance of the stents.