Functionalized Mesoporous Silica via an Aminosilane Surfactant Ion Exchange Reaction: Controlled Scaffold Design and Nitric Oxide Release.

Nitric oxide-releasing mesoporous silica nanoparticles (MSNs) were prepared using an aminosilane-template surfactant ion exchange reaction. Initially, bare silica particles were synthesized under basic conditions in the presence of cetyltrimethylammonium bromide (CTAB). These particles were functionalized with nitric oxide (NO) donor precursors (i.e., secondary amines) via the addition of aminosilane directly to the particle sol and a commensurate ion exchange reaction between the cationic aminosilanes and CTAB. N-Diazeniumdiolate NO donors were formed at the secondary amines to yield NO-releasing MSNs. Tuning of the ion exchange-based MSN modification approach allowed for the preparation of monodisperse particles ranging from 30 to 1100 nm. Regardless of size, the MSNs stored appreciable levels of NO (0.4-1.5 μmol mg(-1)) with tunable NO release durations (1-33 h) dependent on the aminosilane modification. Independent control of NO release properties and particle size was achieved, demonstrating the flexibility of this novel MSN synthesis over conventional co-condensation and surface grafting strategies.