Nitric Oxide-Releasing Xerogels Synthesized from N‑Diazeniumdiolate-Modified Silane Precursors

Nitric oxide (NO)-releasing xerogel materials were synthesized using N-diazeniumdiolate-modified silane monomers that were subsequently co-condensed with an alkoxysilane. The NO-release characteristics were tuned by varying the aminosilane structure and concentration. The resulting materials exhibited maximum NO release totals and durations ranging from 0.45–3.2 μmol cm^–2 and 20–90 h, respectively. The stability of the xerogel networks was optimized by varying the alkoxysilane backbone identity, water to silane ratio, base catalyst concentration, reaction time, and drying conditions. The response of glucose biosensors prepared using the NO-releasing xerogel (15 mol % N-diazeniumdiolate-modified N-2-(aminoethyl)-aminopropyltrimethoxysilane) as an outer sensor membrane was linear (R² = 0.979) up to 24 mM glucose. The sensitivity (3.4 nA mM^–1) of the device to glucose was maintained for 7 days in phosphate buffered saline. The facile sol–gel synthetic route, along with the NO release and glucose biosensor characteristics, demonstrates the versatility of this method for biosensor membrane applications.