Preparation of Nitric Oxide (NO)-Releasing Sol−Gels for Biomaterial Applications

Nitric oxide (NO)-releasing sol−gel materials are synthesized by combining amine-functionalized alkoxysilanes (aminosilanes) with alkyltrimethoxysilanes (alkylsilanes). Upon hydrolysis and condensation, the amine-functionalized silanes are covalently bound to the alkyltrimethoxysilane backbone and easily converted to diazeniumdiolate NO donors via exposure to high pressures of NO. Immersion of the sol−gel into solution is not required to initiate NO release. The NO-release characteristics of the sol−gels are easily controlled by varying the type and amount of the aminosilane precursor in the sol. The sol−gel coatings release NO for up to 20 d with average fluxes between 8.0 × 10 - 12 and 5.6 × 10 - 11 mol·s - 1 ·cm - 2 (coating thickness of 50 μm) over the first 10 h. These materials exhibit reduced platelet and bacterial adhesion. The results indicate that sol−gel chemistry may be an effective strategy for preparing coatings that release NO both controllably and locally for a range of applications including blood- and tissue-based devices.