Transformative metal-ligand nanocoating for dual antibacterial and antithrombotic functionality in hemodialysis...

Hemodialysis catheters are life-saving for end-stage renal disease patients but suffer from catheter-related bloodstream infections and thrombosis, which impair device function and threaten patient survival. Although functional coatings have been employed to mitigate some of these complications, the development of coatings that simultaneously exhibit both antibacterial and antithrombotic properties remains a significant challenge. To address these issues, we developed a PDA/Hep/Cu nanocomposite coating through sequential metal-ligand coordination, polymerization, and covalent immobilization. By employing copper-ammonia complexation, we achieved stable and high-density Cu²⁺ incorporation into the polydopamine (PDA) framework under alkaline conditions, avoiding precipitation problems of conventional methods. Heparin was then covalently conjugated to PDA via carbodiimide chemistry, preserving its antithrombotic bioactivity. Characterization confirmed a hierarchical structure with atomically dispersed Cu²⁺ in square-planar CuN₂O₂/CuN₄ coordination and effective heparin immobilization. In vitro assays showed initial antibacterial efficacy exceeding 99% against S. aureus and E. coli, with sustained activity (99.2% for S. aureus and 98.6% for E. coli) after 10-day PBS immersion. The coating reduced platelet adhesion by 32.4%, prolonged partial thromboplastin time by 24 seconds, and exhibited excellent biocompatibility (hemolysis <5%, cell viability 99.66%). In vivo porcine model validated 87.2-91.1% reduced bacterial colonization and 89% lower thrombus weight compared to uncoated catheters. This dual-functional coating synergizes Cu²⁺-mediated antibacterial activity and heparin-derived antithrombotic properties, offering a promising strategy to enhance hemodialysis catheter safety and longevity, with potential applications in other blood-contacting medical devices.