(A-5) Biomimetic catheter surface with dual action NO releasing and generating properties for enhanced antimicrobial efficacy

Introduction:: Infection of indwelling catheters through bacterial adhesion on the catheter surface is a common healthcare problem, resulting in higher morbidity and mortality. Each year, 80,000 patients in ICU suffer from catheter-related bloodstream infections[1]. Nitric oxide (NO) releasing materials have shown promise in exhibiting antibacterial properties without the risk of antibacterial resistance due to their very short half-life (few seconds). Polymers releasing NO at endogenous levels (ca. 0.5-4x10^-10 mol cm^-2 min^-1) have been used to make blood-contacting medical devices such as catheters more biocompatible [2]. To demonstrate the catalytic NO release and generation through the action of Selenium (Se), a S-nitrosoglutathione (GSNO) and Se incorporated catheter with varying wt% of Se was prepared and analyzed. The NO flux achieved through the interaction of GSNO and Se is considered NO release whereas the NO flux achieved through the interaction of infused glutathione (GSH) and GSNO to mimic endogenous conditions is considered NO generation. The catheters were further studied for surface properties, antibacterial activity, cytocompatibility, and storage and sterilization resistance which are important aspects of the clinical translation of the device.

Materials and Methods:: The tested catheters were prepared by dip coating a 2mm mandrel with a ChronoSil-based polymer solution. Blank ChronoSil solution, GSNO solution (10 wt%), and Se solution (1 wt%, 5 wt%, 10 wt%) were used to fabricate different types of catheters. All catheters were prepared by dip coating the mandrel 40 times with 2 minutes of drying time in between the coats. To determine the real-time NO release, 10% GSNO catheters with 0%, 1%, 5% and 10% Se were incubated in 10 mM PBS at 37 °C and measured for the NO release using a chemiluminescence Nitric Oxide Analyzer (NOA) 280i (Zysense, Frederick, CO). Similarly, NO generation through the catalytic activity of Se was measured by the infusion of glutathione (GSH) and GSNO into the PBS. The amount of GSNO leaching from the catheters was studied using UV-Vis spectroscopy. The catheters were also assessed for antibacterial ability using 24 h bacterial adhesion against E. coli and S. aureus. Finally, the cytocompatibility of the catheter was tested against 3T3 mouse fibroblast cells.

Results, Conclusions, and Discussions:: All the tested catheters i.e., 1%, 5% & 10% Se-GSNO were able to release and catalytically generate NO at physiologically relevant levels for at least 5 days. The presence of Se demonstrated mass fraction dependent NO release (black bar) and NO generation (red bar) from the catheters (Figure 1). With the presence of both NO release and generating aspects, the catheter can release a high amount of NO initially to combat infection and then generate NO from endogenous GSH and GSNO even after the depletion of the active GSNO layer. The catheters showed < 3% GSNO leaching over 4 d and demonstrated cytocompatibility with >80% relative cell viability for all test groups. The synergy of GSNO and Se at 10% Se-GSNO led to a 97.02% and 93.24% reduction in the adhesion of clinically relevant strains of E. coli and S. aureus, respectively.
The Se and GSNO incorporated catheters were able to catalytically generate higher levels of NO when compared to the control. Additionally, a significant reduction in adhered bacteria was achieved through the synergy of Se and GSNO. This study highlights the potential Se and GSNO combined material for enhanced antimicrobial activity.


Acknowledgements (Optional): :

References (Optional): : 1. N.P. O'Grady., et al., CDC MMWR 2002, 51 (RR10) 1-26.

2. E.J. Brisbois., et al., J Mater Chem B 2015, 3(8) 1639-164.