Nitric Oxide-Releasing Xerogel Microarrays Prepared with Surface-Tailored Poly(dimethylsiloxane) Templates

Surface graft polymerization with poly(ethylene glycol) acrylate is reported as an effective method for modifying the surface of poly(dimethylsiloxane) array templates thus enabling the preparation of nitric oxide (NO)-releasing xerogel micropatterns. The surface wettability of PEGA-grafted templates was sufficient to overcome the flow resistance of ethyltrimethoxysilane (ETMOS) sol solutions and allow the formation of xerogel microarrays via capillary action of sol through the template channels. Due to the combined versatility of both sol-gel chemistry and micropatterning, substrates were modified with a range of aminosilane-doped xerogel microarrays with variable NO release properties. Several parameters were studied including (1) NO surface flux as a function of type and concentration of aminosilane Nodonor precursor; (2) micropattern dimensions for maximizing surface flux and duration of NO release; and (3) the effect of microstructure separation on localized NO surface concentration as determined with a NO-selective ultramicroelectrode sensor. Xerogel microarrays were characterized by initial NO surface fluxes ranging from 3.9 ± 0.5 to 73.6 ± 5.7 pmol·cm^-2·s^-1. Although the NO surface flux subsided with time as the finite reservoir within the xerogel became depleted, the duration of measurable NO release was double that of previously reported MTMOS arrays. Thus, NO-releasing aminosilane-modified ETMOS arrays may represent a promising strategy for further improving the in vivo biocompatibility of implantable sensors.