Photoinitiated Nitric Oxide-Releasing Tertiary <i>S</i>-Nitrosothiol-Modified Xerogels

The synthesis of a tertiary thiol-bearing silane precursor (i.e., <i>N</i>-acetyl penicillamine propyltrimethoxysilane or NAPTMS) to enable enhanced NO storage stability at physiological temperature is described. The novel silane was co-condensed with alkoxy- or alkylalkoxysilanes under varied synthetic parameters (e.g., water to silane ratio, catalyst and solvent concentrations, and reaction time) to evaluate systematically the formation of stable xerogel films. The resulting xerogels were subsequently nitrosated to yield tertiary RSNO-modified coatings. Total NO storage ranged from 0.87 to 1.78 μmol cm^–2 depending on the NAPTMS concentration and xerogel coating thickness. Steric hindrance near the nitroso functionality necessitated the use of photolysis to liberate NO. The average NO flux for irradiated xerogels (20% NAPTMS balance TEOS xerogel film cast using 30 μL) in physiological buffer at 37 °C was ∼23 pmol cm^–2 s^–1. The biomedical utility of the photoinitiated NO-releasing films was illustrated by their ability to both reduce <i>Pseudomonas aeruginosa</i> adhesion by ∼90% relative to control interfaces and eradicate the adhered bacteria