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

Abstract

Nitric oxide (NO)-releasing sol-gel materials are synthesized by combining aminefunctionalized 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.

Reduced foreign body response at nitric oxide-releasing subcutaneous implants

“…Diazeniumdiolate-modified xerogels have been studied previously as coatings to reduce both platelet and bacterial adhesion via NO release [28]. Herein, the tissue and wound healing properties of NO-releasing xerogel coatings were evaluated in a subcutaneous implant rat model.…”

“…NO release was conferred to medical-grade silicone elastomer implants via coating with a well-characterized NO-releasing xerogel polymer [18,28]. Capsule formation, angiogenesis, and the inflammatory response were monitored at 1, 3, and 6 weeks via histological examination of explanted tissue samples.…”

Inhibition of implant-associated infections via nitric oxide release

“…Sol-gel chemistry represents an easy and versatile method for applying NO release coatings to a variety of medical devices. Indeed, NO release from sol-gel-derived coatings is highly tunable [4,5]. By utilizing coatings capable of releasing NO, the natural antimicrobial ability of the immune system may be augmented to prevent the survival of pathogenic bacteria at implant surfaces (Fig.…”

Modulated nitric oxide delivery in three-dimensional biomaterials for vascular functionality

“…µM/s/cm 2 during the initial 10 h. [79] In vitro study showed a flux-dependent platelet adhesion on the xerogels, suggesting the NO-releasing xerogels might be useful for short-term applications.…”

“…Marxer et al [79] reported the method to incorporate NO donors within a cross-linked silica xerogel matrix. Highly cross-linked amine-containing networks could be produced using sol-gel chemistry with amine-functionalized alkoxysilanes (aminosilanes) and alkyltrimethoxysilanes (alkylsilanes).…”