Influences of Stent Design on In-Stent Restenosis and Major Cardiac Outcomes: A Scoping Review and Meta-Analysis

Blood-repellent and anti-corrosive surface by spin-coated SWCNT layer on intravascular stent materials

Despite intravascular bare metallic stents (BMS) being indispensable products in cardiovascular surgery, they face in-stent restenosis (ISR), resulting in stent failure or secondary surgical operation necessity. Accumulation or corrosion processes are key factors that promote ISR development in a vascular pathway, including an intravascular stent. The ISR can be inhibited by increasing the blood-repellency, and electrochemical corrosion resistance features using surface modification techniques on intravascular stent materials. In this study, Single-Walled Carbon Nanotube (SWCNT) structures were deposited using the spin-coating method on stent specimens made of 316L, 316LVM, CoCr-alloy, and Ti-alloy. Hydrophobicity and blood-repellency functions of coated and uncoated specimens were analysed by the Contact Angle (CA) values for distilled water (DIW), glycerol, blood plasma, and total-blood droplets using a computer-controlled goniometer system. Using a potentiostat, the electrochemical corrosion resistance features were analysed from obtained Electrochemical Impedance Spectroscopy (EIS) and Tafel curves in 37 °C Simulated Body Fluid (SBF) mimicking the human blood plasma. Due to the CA values below 90°, the repellency limit for hydrophobicity and blood-repellency, bare specimens performed hydrophilic and blood-philic features. However, SWCNT coating increased the repellency functions to 95° for DIW and 96° for total blood. The electrochemical corrosion resistance analysis showed that 1.433 kΩ cm² polarization resistance and 1.07 kΩ cm² electrochemical impedance of bare specimens increased to 142.8 kΩ cm² and 141.3 kΩ cm² by SWCNT coating. These corrosion resistance enhancements led to ratios of 78.13% inhibition in the corrosion rate and mass loss rate per year for SWCNT-coated 316LVM specimens. The maximum inhibition efficiency was observed for SWCNT-coated 316LVM specimens with a ratio of 87.92%. Obtained results indicate that SWCNT coating of the intravascular stents can inhibit the ISR risks of the BMS group.