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 x 10(-12) and 5.6 x 10(-11) mol(.)s(-1.)cm(-2) (coating thickness of 50 mum) 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.