Nitric oxide-releasing silica nanoparticles with varied surface hydrophobicity

Hydrocarbon- and fluorocarbon-based silanes were grafted onto the surface of amine-containing silica nanoparticles to achieve materials of varied surface hydrophobicity. X-ray photoelectron spectroscopy and direct polarization solid-state nuclear magnetic resonance spectroscopy were used to confirm the presence of surface-grafted functionalities. Changes in hydrophobicity were illustrated by assessing the stability of aqueous particle suspensions using dynamic light scattering. Following surface modification, the amines were converted to N-diazeniumdiolate nitric oxide (NO) donors to yield nanoparticles with tunable nitric oxide (NO) release kinetics dependent on the rate of water uptake into the silica structures. Moreover, modification of the particle surface hydrophobicity allowed for the preparation of NO-releasing electrospun polymer fibers with improved particle incorporation and decreased particle leaching compared to fibers doped with unmodified particles. Methods for tuning particle surface chemistry (e.g., hydrophobicity) while maintaining control over size and structure will enable the optimization of such NO-release vehicles for specific therapeutic applications.