Poster O7 - Multifunctional Antimicrobial and Antifouling Catalytic Nitric Oxide-Releasing Medical Devices for Blood-Contacting Applications

Introduction: Medical devices are a crucial component of healthcare and are exposed to extensive biological systems and environments. This exposure prevalent complications such as hospital acquired infections. These complications can stem from bacterial infection, surface fouling, and blood clotting through thrombus formation. NO donor molecule S-nitroso-N-acetylpenicillamine (SNAP) is a prominent molecule that has shown to have direct biomedical device integration success due to its controlled NO release and possesses significant cytocompatibility, antimicrobial, and anti-thrombotic properties when exposed to various biological environments. This molecule releases NO through cleavage of the S-NO bond in presence of catalysis facilitated by the presence of light, heat, and interaction with metal ions1. Further combination strategies to enhance the role of these molecules have aided in the development of promising clinical solutions for addressing complications associated with indwelling medical devices. Recent advances in NO research demonstrate that combination strategies using NO donor molecules with metal ions such as copper nanoparticles (Cu) provide a controlled release of NO into the system to maximize the benefits of the molecule while not being toxic to cells2, 3. In addition, the implementation of liquid infusion (LI) into an NO releasing polymer has shown promising preliminary success in drastically promoting anti-fouling properties of a device surface4. Herein, the NO donor SNAP was combined with metal nanoparticles to catalyze NO release from the surface to promote antimicrobial and antiplatelet effects. In addition, silicone oil was implemented into the polymeric matrix via swelling in order to yield anti-fouling capabilities to the substrate.

Materials and

Methods: The proposed material was fabricated using a solvent casting method of a clinically relevant silicone rubber blended with SNAP at specific concentrations. The cured film was swelled with varying viscosities of silicone oil and used for experimentation. In order to conduct characterization studies, UV-vis spectroscopy was used for quantifying NO donor leaching, a contact angle goniometer was implemented for sliding angle studies, and a gold standard chemiluminescence method employing a Nitric Oxide Analyzer (NOA) was used for analyzing nitric oxide release kinetics from the material. The antimicrobial efficacy of the material was evaluated in a 24 h adhesion assay using clinically relevant bacterial strains Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 6538). Cytocompatibility was assessed with MTT assay using NIH 3T3 mouse fibroblast cells. Finally, blood compatibility studies were conducted to analyze hemocompatibility, fibrinogen adsorption, and platelet activation on the surface of the materials.

Results, Conclusions, and Discussions: The fabricated material displayed viable NO release in addition to the copper nanoparticles and liquid infusion surface modifications. Cu LI NO releasing films displayed elevated NO release compared to controls with an NO flux of 1.80 x10-10 mol min-1 cm-2 and continued to release at physiological levels for a duration of seven days (Figure 1). Biological studies displayed viable results with >2 log reduction in bacterial adhesion and 72.49% reduction in platelet activation (Figure 2). The antifouling nature of the slippery surface modification displayed exemplary results in fibrinogen adsorption studies with 77.91% reduction in protein adsorption compared to controls. These results were complemented with cytocompatibility studies which displayed over 70% viability across all combinations of sample types in accordance with ISO 10993-5 standards.

This study combined multiple surface modifications to a clinically relevant silicone rubber medical device substrate. The material exhibited properties that address complications found in hospitals in broad-spectrum and specialized medical device applications. With the implementation of these components, the material possesses the potential to address issues related to eradication of bacterial infection, surface fouling, and thrombosis.

Acknowledgements (Optional): References
(1) Brisbois, E. J.; Handa, H.; Major, T. C.; Bartlett, R. H.; Meyerhoff, M. E. Long-term nitric oxide release and elevated temperature stability with S-nitroso-N-acetylpenicillamine (SNAP)-doped Elast-eon E2As polymer. Biomaterials 2013, 34 (28), 6957-6966. DOI: https://doi.org/10.1016/j.biomaterials.2013.05.063.
(2) Pant, J.; Goudie, M. J.; Hopkins, S. P.; Brisbois, E. J.; Handa, H. Tunable Nitric Oxide Release from S-Nitroso-N-acetylpenicillamine via Catalytic Copper Nanoparticles for Biomedical Applications. ACS Applied Materials & Interfaces 2017, 9 (18), 15254-15264. DOI: 10.1021/acsami.7b01408.
(3) Gorren, A. C.; Schrammel, A.; Schmidt, K.; Mayer, B. Decomposition of S-nitrosoglutathione in the presence of copper ions and glutathione. Arch Biochem Biophys 1996, 330 (2), 219-228. DOI: 10.1006/abbi.1996.0247 From NLM.
(4) Goudie, M. J.; Pant, J.; Handa, H. Liquid-infused nitric oxide-releasing (LINORel) silicone for decreased fouling, thrombosis, and infection of medical devices. Scientific Reports 2017, 7 (1), 13623. DOI: 10.1038/s41598-017-14012-9.