Tunable Nitric Oxide Release from S-Nitroso-N-acetylpenicillamine via Catalytic Copper Nanoparticles for Biomedical Applications

Abstract

The quest for novel therapies to prevent bacterial infections and blood clots (thrombosis) is of utmost importance in biomedical research due to the exponential growth in the cases of thrombosis and blood infections and the emergence of multi-drug-resistant strains of bacteria. Endogenous nitric oxide (NO) is a cellular signaling molecule that plays a pivotal role in host immunity against pathogens, prevention of clotting, and regulation of systemic blood pressure, among several other biological functions. The physiological effect of NO is dose dependent, which necessitates the study of its tunable release kinetics, which is the objective of this study. In the present study, polymer composites were fabricated by incorporating S-nitroso-N-acetylpenicillamine (SNAP) in a medical-grade polymer, Carbosil, and top-coated with varying concentrations of catalytic copper nanoparticles (Cu-NPs). The addition of the Cu-NPs increased the NO release, as well as the overall antimicrobial activity via the oligodynamic effect of Cu. SNAP (10 wt %) composites without Cu-NP coatings showed a NO flux of 1.32 ± 0.6 × 10 mol min cm, whereas Cu-NP-incorporated SNAP films exhibited fluxes of 4.48 ± 0.5 × 10, 4.84 ± 0.3 × 10, and 11.7 ± 3.6 × 10 mol min cm with 1, 3, and 5 wt % Cu-NPs, respectively. This resulted in a significant reduction (up to 99.8%) in both gram-positive and gram-negative bacteria, with very low platelet adhesion (up to 92% lower) as compared to that of the corresponding controls. Copper leachates from the SNAP films were detected using the inductively coupled plasma-mass spectrometry technique and were found to be significantly lower in concentration than the recommended safety limit by the FDA. The cell viability test performed on mouse fibroblast 3T3 cells provided supportive evidence for the biocompatibility of the material in vitro.

A multi-defense strategy: Enhancing bactericidal activity of a medical grade polymer with a nitric oxide donor and surface-immobilized quaternary ammonium compound

“…This problem can be addressed by the application of NO. The small molecular size of NO allows it to diffuse through the bacterial biofilm and kill the bacterial cells which are otherwise resistant to bactericidal agents [53, 54]. In other words, the gradually released NO extended the life of BPAM by lowering the concentration of surrounding bacteria near the surface.…”

“…In the past, we have shown that SNAP based NO releasing polymers have many desirable properties from a translational perspective such as the long-term storage stability (6 months), ease of sterilization, and extended NO release (> 2 weeks) without negatively affecting the physical characteristics, bacterial inhibition, biocompatibility, and hemocompatibility of the polymer [43, 53, 62, 63]. Similarly, the surface grafted BPAM has been reported to exhibit excellent antimicrobial activity against Gram-positive and Gram-negative bacteria on instant contact due to high surface charge density of the deposited BPAM thin film [20].…”

Nitric oxide releasing vascular catheters for eradicating bacterial infection

“…Incorporation of a NO releasing donor molecule such as SNAP in a hydrophobic polymer such as E2As can significantly inhibit the attached viable bacteria on the polymer surface . NO has inherent antithrombotic and antibacterial properties.…”

“…NO has inherent antithrombotic and antibacterial properties. It is a cellular signaling molecule which is released at a flux of 0.5–4.0 × 10 −10 mol/mincm 2 in the human body by endothelial cells lining the blood vessels in addition to macrophages and sinus cavities . The unpaired NO electron is extremely reactive and has a very short half‐life of <5 s, allowing it to only have a localized and immediate impact .…”

“…The use of NO as an antibacterial agent is not expected to result in any resistance due to its short half‐life, rapid reduction of microbial load and nonspecific action . Furthermore, studies have shown that the SNAP‐doped E2As polymer does not result in any cytotoxicity against mammalian cells in vitro . The absence of antibiotic resistance and cytotoxicity makes NO based antimicrobial therapy, a better alternative to other commonly used strategies such as antibiotics‐based approaches …”