Antimicrobial efficacy of a nitric oxide-releasing ampicillin conjugate catheter lock solution on clinically-isolated antibiotic-resistant bacteria

Wearable nitric oxide-releasing antibacterial insert for preventing device-associated infections

Medical device-associated infections are a pervasive global healthcare concern, often leading to severe complications. Bacterial biofilms that form on indwelling medical devices, such as catheters, are significant contributors to infections like bloodstream and urinary tract infections. This study addresses the challenge of biofilms on medical devices by introducing a portable antimicrobial catheter insert (PACI) designed to be efficient, biocompatible, and anti-infective. The PACI utilizes nitric oxide (NO), known for its potent antimicrobial properties, to deter bacterial adhesion and biofilm formation. To achieve this, a photoinitiated NO donor, S-nitroso-N-acetylpenicillamine (SNAP), is covalently linked to a polydimethylsiloxane (PDMS) polymer. This design allows for higher NO loading for long-term impact and prevents premature donor leaching, a common challenge with SNAP-blended polymers. The SNAP-PDMS material was applied to a side-glowing fiber optic and connected to a wearable light module emitting 450 nm light, creating a functional antimicrobial insert. Activation of the fiber optic, accomplished with a one-click mechanism, enables real-time NO release, maintaining controlled NO levels for a minimum of 24  hours. The therapeutic levels of NO released via photocatalysis from the PACI demonstrated remarkable efficacy, with >90 % reduction in bacterial viability against S. aureus, S. epidermidis, and P. mirabilis without any cytotoxic impact on mammalian cells. This study underscores the potential of the NO-releasing insert in clinical settings, providing a portable and adaptable solution for preventing catheter-associated infections.

Engineering Nitric Oxide-Releasing Antimicrobial Dental Coating for Targeted Gingival Therapy

Bacterial biofilms play a central role in the development and progression of periodontitis, a chronic inflammatory condition that affects the oral cavity. One solution to current treatment constraints is using nitric oxide (NO)─with inherent antimicrobial properties. In this study, an antimicrobial coating is developed from the NO donor S-nitroso-N-acetylpenicillamine (SNAP) embedded within polyethylene glycol (PEG) to prevent periodontitis. The SNAP-PEG coating design enabled a controlled NO release, achieving tunable NO levels for more than 24 h. Testing the SNAP-PEG composite on dental floss showed its effectiveness as a uniform and bioactive coating. The coating exhibited antibacterial properties against Streptococcus mutans and Escherichia coli, with inhibition zones measuring up to 7.50 ± 0.28 and 14.80 ± 0.46 mm2, respectively. Furthermore, SNAP-PEG coating materials were found to be stable when stored at room temperature, with 93.65% of SNAP remaining after 28 d. The coatings were biocompatible against HGF and hFOB 1.19 cells through a 24 h controlled release study. This study presents a facile method to utilize controlled NO release with dental antimicrobial coatings comprising SNAP-PEG. This coating can be easily applied to various substrates, providing a user-friendly approach for targeted self-care in managing gingival infections associated with periodontitis.

Dielectric and Magnetic Composites of Fe3O4@APNs for Superior Microwave Thermal Effect

As for the deep tissue infections of chronic osteomyelitis, antibiotics are hard to deliver into the infected bone tissue, which makes it difficult to be cured completely in clinic. Microwave has strong penetration, and the medium can produce a good bactericidal effect through the microwave thermal effect (MTE). Here, a new microwave sensitizer (Fe3O4@APNs) was prepared and evaluated. Black phosphorus nanosheets modified with phytic acid dodecasodium (APNs) were fabricated by a liquid-phase exfoliation method that exhibited good water oxygen stability. A complex with Fe3O4 compound and APNs (Fe3O4@APNs) was formed by an ultrasonic mixing process, which showed excellent MTE (quickly increased to 53.5 °C in 5 min at 2.45 GHz, 10 W/cm2) via dielectric versus magnetic loss (reflect loss value of -5.94 dB at 2.45 GHz). The Fe3O4@APNs microwave sensitizer developed in this study has an outstanding in vitro antibacterial effect and might show promise for the treatment of chronic osteomyelitis enabled by local tissue heating via the MTE.

Enhanced antibacterial efficacy against antibiotic-resistant bacteria via nitric oxide-releasing ampicillin polymer substrates

The emergence of antibiotic-resistant bacteria poses a pressing threat to global health and is a leading cause of healthcare-related morbidity and mortality. Herein, we report the fabrication of medical-grade polymers incorporated with a dual-action S-nitroso-N-acetylpenicillamine-functionalized ampicillin (SNAPicillin) conjugated molecule through a solvent evaporation process. The resulting SNAPicillin-incorporated polymer materials act as broad-spectrum antibacterial surfaces that improve the administration efficacy of conventional antibiotics through the targeted release of both nitric oxide and ampicillin. The polymer surfaces were characterized by scanning electron microscopy and static contact angle measurements. The nitric oxide (NO) release profile and diffusion of SNAPicillin from polymers were quantified using a chemiluminescence-based nitric oxide analyzer (NOA) and ultraviolet-visible (UV-vis) spectroscopy. As a result, the films had up to 2.96 × 10-7 mol cm-2 of total NO released within 24 hr. In addition, >79 % of the SNAPicillin reservoir was preserved in the polymers after 24 hr of incubation in the physiological environment, indicating their longer-term NO release ability and therapeutic window for antibacterial effects. The SNAPicillin-incorporated polymers reduced the viability of adhered bacteria in culture, with >95 % reduction found against clinically relevant strains of Staphylococcus aureus (S. aureus). Furthermore, SNAPicillin-modified surfaces did not elicit a cytotoxic effect toward 3T3 mouse fibroblast cells, supporting the material's biocompatibility in vitro. These results indicate that the complementary effects of NO-release and ampicillin in SNAPicillin-eluting polymers can enhance the properties of commonly infected medical device surfaces for antibacterial purposes.