Nanostructured Silver-Coated Silicone Tracheal Stents Confer Hybrid Anti-Biofilm Activity In Vivo

Bacterial colonization and biofilm formation remain major limitations of airway stenting, contributing to device obstruction and infection-related complications. Here, we translated to silicone tracheal stents a previously developed plasma-assisted micro/nanostructured silver interface designed to provide hybrid anti-biofilm activity through reduced bacterial adhesion and controlled silver release. The coated stents were characterized to confirm the generation of the nanostructured silver coating and were evaluated against Gram-positive and Gram-negative bacteria in vitro, followed by in vivo assessment in a miniature pig airway model. In vitro, the coating reproduced the dual bacteriophobic and silver-mediated antimicrobial behavior previously observed on model silicone surfaces. In vivo, animals implanted with silver-coated stents showed lower endpoint bacterial loads in bronchial washes than those receiving commercial stents (1.0 × 108 vs 1.2 × 109 CFU/mL, p =0.0085). Bacterial adhesion on explanted stents was also markedly lower for coated devices (109 vs 1011 CFU /cm2, 99.8% reduction, p < 0.0001), and scanning electron microscopy showed a thinner and less mature biofilm structure. Potentially pathogenic bacteria, including Klebsiella pneumoniae and Pseudomonas aeruginosa, were more frequently detected on commercial stents, whereas coated stents were mainly associated with the native respiratory microbiota. Overall, these results indicate that nanostructured silver-coated silicone tracheal stents display hybrid anti-biofilm functionality in a challenging in vivo airway setting.