More lipophilic dialkyldiamine-based diazeniumdiolates: synthesis, characterization, and application in preparing...

The synthesis, characterization, and biomedical application in preparing more thromboresistant polymeric coatings for a series of lipophilic dialkyldiamine-based diazeniumdiolatesare described. Dialkylhexamethylenediamine diazeniumdiolates of the form RN[N(O)NO](-)(CH(2))(6)NH(2)(+)R, where R = CH(3), CH(2)CH(3), (CH(2))(2)CH(3), (CH(2))(3)CH(3), (CH(2))(4)CH(3,) (CH(2))(5)CH(3), and (CH(2))(11)CH(3), are prepared via reaction of the corresponding diamine with NO. The more lipophilic diazeniumdiolates [e.g., R = (CH(2))(3)CH(3)] can be incorporated into hydrophobic polymeric films (e.g., plasticized PVC), and the resulting materials release NO for extended periods of time upon exposure to PBS buffer. The mechanism of NO release from these films is examined in detail. More stable initial NO release can be achieved by adding lipophilic anionic species (e.g., tetraphenylborate derivative) to the polymeric material to buffer the activity of protons within the organic phase. It is shown that the use of these new lipophilic NO-donors in polymers provides the ability to tailor NO release rates for a variety of medical applications. As an example, polymers doped with N,N'-dibutylhexamethylenediamine diazeniumdiolate and a tetraphenylborate derivative are employed as coatings for vascular grafts in sheep. The NO release grafts exhibited enhanced performance and had an average 95% thrombus-free surface area compared to 42% for the corresponding control grafts when examined after 21d of implantation.