Development of chemical sensors based on redox-dependent receptors: N,N'-dimethyldiazapyrenium-modified electrodes |
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Authors: | Lilienthal Ninette D Alsafar Habiba Conerty Jason Fernandez Rayne Kong Cecilia Smith Diane K |
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Affiliation: | Department of Chemistry, San Diego State University, San Diego, California 92182-1030, USA. |
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Abstract: | Electrodes modified with Nafion films containing 2,7-dimethyldiazapyrenium (DAP2+) were prepared and characterized with voltammetry by themselves and in the presence of organic substrates. The large, planar, electron-poor aromatic surface in DAP2+ facilitates pi-stacking interactions with other planar aromatic molecules, particularly those that are negatively charged or electron-rich. Previous studies showed that the reduction of DAP2+ decreases the strength of these interactions, making the binding redox-dependent, and resulting in negative shifts in the E(1/2) of DAP2+/+. This study shows that the redox-dependent binding ability of DAP2+ is retained in Nafion, but the selectivity is considerably different. Most significantly, the electron-rich, neutral aromatic compounds that produced small shifts in the E(1/2) of DAP2+/+ in solution cause much larger shifts, up to -110 mV, with the modified electrodes. With indole as a substrate, Nernstian behavior is observed (-60 mV shift per logindole]) between 10 and 0.5 mM. |
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