(A-20) Multifunctional Nitric Oxide-Releasing and Slippery Nanoemulsion-Infused Porous Surfaces

Introduction:: Introduction. The need for more biocompatible materials for medical devices remains a major concern because infection, thrombosis, and biofouling have become some of the leading causes of medical device failure and patient morbidity and mortality. Over the last few years, nitric oxide (NO)-releasing technologies have been explored to address the ever-growing issue of bacterial infections, being able to eradicate infections from common bacteria such as S. aureus and E. coli. However, NO lacks anti-fouling capabilities. To compensate, combination strategies that use NO and anti-fouling surfaces (e.g. slippery lubricant-infused porous surfaces) have been explored to make up for the deficit. In this work, we developed and assessed a novel material that combines the antibacterial capabilities of a nitric oxide (NO)-releasing substrate with the anti-fouling effects of a nanoemulsion (NE)-infused slippery surface.


Materials and Methods:: Materials & Methods. A covalently bound SNAP (S-nitroso-acetylpenicillamine) to PDMS (polydimethylsiloxane) was fabricated (SNAP-PDMS) and infused with a n-hexadecane-based water-in-oil (w/o) nanoemulsion. The NO released from the reported SNAP-PDMS NE-infused surface (SNAP-PDMS-NE) was measured for 7 days to ensure the material would provide therapeutic levels of NO for that duration of time. The NE coating stability was also assessed via measurement of the surface’s sliding angle over 7 days after incubation in 10 mM phosphate buffered saline (PBS) with 100 μM ethylenediaminetetraacetic acid (EDTA) shaking at 150 rpm. In vitro biological assessments, such as a 24 h bacterial adhesion assay, a platelet adhesion via Lactate dehydrogenase (LDH) assay, and a cytocompatibility via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, were also performed to determine the SNAP-PDMS-NE’s potential to prevent infection, thrombosis, and adverse immune responses.


Results, Conclusions, and Discussions:: Results & Discussion. The NO release of SNAP-PDMS-NE was sustained for 7 days at physiologically relevant levels (0.5 – 4 x 10^-10 mol min^‑1 cm^-2) (Figure 1); the sustained release of NO aids in the long-term prevention of bacterial infection as the NO released would be actively eradicating bacteria that come in contact with the material. In addition to the prolonged NO release, the infused NE layer maintained a slippery nature and sliding angle >20^o for 7 days, indicating the replenishing of the lubricant layer after physical removal. The longevity of the NE slippery surface also suggests that the onset of bacterial infection and thrombus formation would be delayed or be prevented altogether as bacteria and blood cells (red blood cells, platelets, etc.) would not be able to adhere to the surface. In vitro bacterial adhesion assessments showed that the SNAP-PDMS-NE was able to efficiently reduce S. aureus and E. coli adhesion by 99.23% and 96.15%, respectively. NO’s ability in combination with the NE’s ability to prevent bacterial adhesion due to the n-hexadecane’s relatively low surface tension¹ was able to significantly reduce the number of bacteria adhered to the surface. Platelet adhesion on SNAP-PDMS-NE samples were reduced by 89.92% compared to control. The NO-releasing slippery surface was able to prevent significantly more platelets from adhering to the material surfaces compared to SNAP-PDMS alone, which is corroborated by previous reports of anti-fouling strategies in combination with NO.²

Conclusion. Overall, this material is a promising candidate for future antibacterial and anti-fouling methods for future devices (e.g. catheters, tubing, cannulas) due to its antibacterial activity, anti-fouling capabilities, and cytocompatibility.




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References (Optional): : References. [1] Klein T, et al. J. Chem. Eng. 2019; 64 (9), 4116-4131.

[2] Goudie MJ, et al. Sci. Rep. 2017; 7 (1).