Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 21. Selective Chemical Sensing Using Sulfonated Polystyrene-block-poly(ethylene-ran-butylene)block-polystyrene Thin Films

Abstract

Spectroelectrochemical sensors combine three modes of selectivity in a single device (electrochemistry, spectroscopy, and selective partitioning). A thin polymer film is coated onto the sensing platform in order to facilitate chemically selective transport to the electrode. The film is an essential part of the sensor because it provides an increase in selectivity and sensitivity by selectively preconcentrating the analyte. Here, we report the next step in the characterization of partially sulfonated polystyrene-block-poly(ethylene-ran-butylene)block-polystyrene (SSEBS) films for the purpose of chemical sensing by examining the selectivity of the sensor fabricated with this novel thin film material. Binary mixtures using model analytes were used to demonstrate the sensor's ability to detect an analyte in the presence of a direct interference. The binary mixtures consisted of Ru(bpy)(3)(2+)/Fe(CN)(6)(3-), Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+), and Ru(bpy)(3)(2+)/Cu(bpy)(2)(2+). Demonstration of the selective partitioning mode using the Ru(bpy)(3)(2+)/Fe(CN)(6)(3-) mixture and absorption detection showed the SSEBS film's preference for Ru(bpy)(3)(2+) over Fe(CN)(6)(3-), and therefore, Fe(CN)(6)(3-) did not interfere with the sensor's response to Ru(bpy)(3)(2+). Furthermore, the importance of the use of three modes together was demonstrated by analysis of the Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+) and the Ru(bpy)(3)(2+)/Cu(bpy)(2)(2+) test mixtures, where both selection of a specific wavelength for absorption and selection of a specific potential window were required to reduce or eliminate the signal from the interference. Finally, analysis of the Ru(bpy)(3)(2+)/Fe(bpy)(3)(2+) test mixture was also demonstrated using fluorescence detection.