Xerogel Optical Sensor Films for Quantitative Detection of Nitroxyl

Xerogel sensing films synthesized via sol−gel chemistry were used to fabricate optical nitroxyl (HNO) sensors. Selective detection of HNO in solution was achieved by monitoring the rates of manganese(III) meso-tetrakis(4-sulfonatophenyl) porphyrinate (MnIIITPPS) reductive nitrosylation in the anaerobic interior of aminoalkoxysilane-derived xerogel films. Nitroxyl permeability in sensor films deposited in round-bottom 96-well plates was enhanced via incorporation of trimethoxysilyl-terminated poly(amidoamine-organosilicon) dendrimers in the xerogel network. The selectivity of MnIIITPPS for HNO, the overall sensitivity, and the working dynamic range of the resulting sensors were characterized. The HNO-sensing microtiter plates were used to quantify pH-dependent HNO generation by the recently described HNO-donor sodium 1-(isopropylamino)diazene-1-ium-1,2-diolate (IPA/NO), and compare HNO production efficiency between IPA/NO and Angeli's salt, a traditional HNO-donor.