Antithrombotic and antibacterial surface coating based on spiky silver nanoparticles: A counterattack against clotting and biofilm

Blood-contacting medical devices such as vascular grafts, stents, and catheters are indispensable in life-saving interventions but remain prone to thrombosis and bacterial infection. These complications are often synergistic, with clot formation facilitating bacterial colonisation and biofilm growth, yet most surface coatings lack active countermeasures once thrombi or biofilms have developed. In this study, we hypothesised that integrating spiky silver-coated iron oxide nanoparticles (AgIONPs) with poly(ethylene glycol) (PEG) into a surface coating could provide both passive and active protection. AgIONPs offer strong photothermal properties under 808 nm laser irradiation for on-demand thrombolysis and biofilm disruption, while PEG contributes antifouling, anticoagulant, and biocompatible characteristics. The optimised AgIONPs-PEG coating exhibited safe photothermal heating (<45 °C), effectively lysed thrombi in static and dynamic models, and disrupted most biofilm biomass after a single irradiation cycle. Antithrombogenicity assays confirmed PEG's ability to reduce biofouling and improve haemocompatibility. Biocompatibility was further validated through <i>in vitro</i>, <i>in ovo</i>, and <i>in vivo</i> assays, with reduced immune-mediated inflammation. These findings highlight a multifunctional, responsive coating that could extend the lifespan and reliability of blood-contacting devices, offering a promising platform for next-generation photothermal materials in biomedical applications.