An electrolyte-stable polymer composite sensor film based on 2.4% boronic acid substituted polyacrylamide (poly[acrylamide-co-3-(methacrylamido)-phenylboronic acid] or P(A-MPBA)) and polydiallyl-dimethyl-ammonium chloride (or PDDACl) is obtained in a coil-by-coil deposition procedure. Based on AFM evidence, the resulting coil aggregate deposits show ca. 5-10 nm diameter and the average film thickness increases with ca. 1 nm per deposition cycle consistent approximately with the solution coil diameter. In electrochemical experiments alizarin red S is employed as a boronic acid indicating redox probe with a Langmuirian binding constant of ca. K ¼ 4 Â 10 6 M À1 and two distinct redox responses tentatively assigned here to two isomeric forms of the complex in oxidized and reduced state. Inter-and intra-coil electron transfer and electron hopping occurs during alizarin red S reduction and back-oxidation. Both smooth and mesoporous ITO substrates are employed.
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