Hydrophilic surface coatings with embedded biocidal silver nanoparticles and sodium heparin for central venous catheters

Central venous catheters (CVCs) have become indispensable in the treatment of neonates and patients undergoing chemotherapy or hemodialysis. A CVC provides easy access to the patient's circulation, thus enabling facile monitoring of hemodynamic parameters, nutritional support, or administration of (cytostatic) medication. However, complications with CVCs, such as bacterial bloodstream infection or thromboembolism, are common. Bloodstream infections, predominantly caused by Staphylococcus aureus, are notoriously difficult to prevent and treat. Furthermore, patients receiving infusion therapy through a CVC are at risk for deep-vein thrombosis, especially of the upper limbs. Several recent clinical trials have shown that prophylactic anticoagulation (low-molecular-weight heparin or vitamin K antagonists) is not effective. Here, we report on the systematic development of a new bifunctional coating concept that can -uniquely- be applied to make CVC surfaces antimicrobial and antithrombogenic at the same time. The novel coating consists of a moderately hydrophilic synthetic copolymer of N-vinylpyrrollidinone (NVP) and n-butyl methacrylate (BMA), containing embedded silver nanoparticles (AgNPs) and sodium heparin. The work demonstrates that the AgNPs strongly inhibit adhesion of S. aureus (reference strain and clinical isolates). Surprisingly, heparin not only rendered our surfaces practically non-thrombogenic, but also contributed synergistically to their biocidal activity.