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Biomaterials

Biomaterials - Poster Session D

Poster B7 - Nitric Oxide Releasing Oil-Infused Porous Surfaces Preventing Infection, Biofilm Formation, and Thrombosis

Friday, October 25, 2024
3:30 PM - 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Current indwelling biomaterials often suffer from issues such as thrombosis, bacterial infection, and biofilm formation due to their lack of antifouling properties. Slippery liquid-infused porous surfaces (SLIPS) have been studied extensively for their ability to repel a wide range of liquids and maintain low contact angle hysteresis, effectively preventing thrombosis and bacterial adhesion. Additionally, nitric oxide (NO), a gaseous endogenous molecule, plays a crucial role in reducing bacterial adhesion and proliferation, as well as preventing platelet adhesion and activation [1]. By incorporating an NO-donor into SLIPS, the materials’ ability to prevent platelet activation will be enhanced in applications involving blood-contact, while also inhibiting bacterial proliferation [2]. The purpose of this project is to evaluate the antibacterial, antiplatelet, and anti-fouling properties of RSNO oil A (A0) and RSNO oil B (B0) through assays measuring viable fibrinogen adhesion, platelet adhesion, bacterial adhesion, and cytotoxicity on silicone rubber substrates.

Materials and

Methods:  The NO-releasing S-Nitrosothiol-based silicone oils (RSNO-Si) were synthesized and swelled into 6mm x 2 mm Sylgard-184 polydimethylsiloxane (PDMS) films to fabricate RSNO-Si treated silicone rubber (RSNO-Si-SR). Post-fabrication, the material was optimized by measuring the swelling rate/ratio of the film in oil, sliding angle, and nitric oxide (NO) release of PDMS. Initial evaluation of the sliding angle revealed an average exceeding 20° indicating poor slippery behavior for A0. Consequently, various dilutions of A0 with a primary oil that is not NO releasing were employed to maintain optimal slippery properties: A1, A2, A3. Initial cytotoxicity was determined through an MTT assay using 3T3 mouse fibroblast cells. The most effective dilution will be defined through assays measuring various protein, bacterial, blood, and cell studies.

Results, Conclusions, and Discussions: The optimal swelling time was determined to be four hours at room temperature. Incorporation of both oils slightly decreased the water contact angle of the silicone substrate. After preliminary sliding angle evaluation, A0 was unable to maintain slippery behavior beyond 24 hours (Figure 1). This is likely due to its branched structure, which hinders the replenishment of the lubricant layer on the polymer surface. To address this, a primary oil that is not NO releasing was used to dilute the nitrosated oils because it is not only miscible with A0, but provides slippery capabilities to silicone rubber. All A0 dilutions remained below 20° over a 14-day testing window, deeming A1, A2, and A3 opportune for further studies to characterize. The NO release for all dilutions was also sustained over the same 14-day timeframe (Figure 2). NO release for B0 has a high burst release on day 0 but subsequently demonstrated a faster decline in NO release over time when compared to A0 and its dilutions. This behavior is likely attributed to B0’s lower stability and higher volatility. For the A0 dilutions, the combination of the primary oil leaching and A0 concentration allows for increased stability in NO release. Due to the high burst releases from A1 and A2, a preliminary cytotoxicity analysis was conducted to ensure biological applicability. Preliminary cytotoxicity analysis was conducted on the A0 dilutions, revealing high burst releases (approximately 50 to 100 flux) within the first 24 hours. Further biological replicates are necessary to draw conclusive insights from these findings. Preliminary characterization assays indicate that A0 dilutions are promising for further optimization. The final RSNO-Si-SR is expected to exhibit stable NO release while preserving its slippery characteristics and anti-fouling properties.

Acknowledgements (Optional):  This material is based upon work supported by a National Science Foundation Research Experienced for Undergraduates (REU) site program under grant No. 1950581.

[1] Brisbois, E. J., Handa, H., Major, T. C., Bartlett, R. H., & Meyerhoff, M. E. (2013). Biomaterials, 34(28), 6957–6966.

[2] Goudie, M. J., Pant, J., & Handa, H. (2017). Scientific reports, 7(1), 13623.