Assessing mechanical properties and stability of silver-doped carbon-coated urethral stent application

Carbon coatings doped with Ag nanoparticles (a-C/Ag) are promising materials to enhance ureteral stents' biological, mechanical, and tribological properties. This paper aims to assess the degradation profile and mechanical behaviour of silicone stents coated with a-C and a-C/Ag films under simulated physiological conditions. a-C coating containing about 5 at. % Ag was deposited on silicone stent substrates by magnetron sputtering. The chemical composition, roughness, and wettability of the coatings were analysed. The morphology and mechanical properties of the coatings were characterised before and after 30 days of immersion in synthetic urine. Remarkably, the a-C/Ag coating demonstrated exceptional resistance to degradation, exhibiting no signs of film delamination even after 30 days of incubation under accelerated degradation conditions. Moreover, the stability of the a-C/Ag coating was evaluated by monitoring its release in synthetic urine, revealing an initial rapid release within the first two days, followed by a controlled and gradual release of silver ions from the coating. Additionally, the a-C/Ag coating practically kept the breaking force of the silicone stent (~5 % loss) with a significant diminution in elongation at break due to the substate embrittlement during the sputtering process. Overall, this study provides valuable insights into the performance of a-C/Ag coating on silicone stents, highlighting their ability to maintain structural integrity, resist degradation, and withstand substantial forces. These findings support the promising potential of a-C/Ag coating in enhancing the reliability and durability of urological stents.