Tuning electropolymerization of boronate-substituted anilines: Fluoride-free synthesis of the advanced affinity transducer

• Fluoride-free synthesis of an advanced affinity transducer.
• Conducting polyaniline-type polymer on the basis of electropolymerization of 2-aminophenylboronic acid.
• Confirmation of the novel reagentless detection principle using another material.

Boronate-substituted polyanilines are able to serve as advanced affinity transducers if synthesized at their highest conductivity and remind properties (particularly, cyclic voltammograms in acidic media) of common conductive polyaniline. This presumes growing conditions, when the substituent promotes electrophilic substitution in para-position relatively amino-group. Thus electropolymerization of 3-aminophenylboronic acid (3-APBA) requires free fluoride ions to convert boronic acid residue to trifluoroborate serving as electron donor. On the contrary, when in ortho-position to amino-group, boronic acid does not hamper the polyaniline-type growth, but its conversion to trifluoroborate inhibits the polymerization. Accordingly, optimal media for electropolymerization of 2-aminobenzeneboronic acid (2-APBA) are strong acidic solutions similar to unsubstituted aniline. Conducting polyaniline-type polymers synthesized from both isomers generate an increase in their conductivity as a response to polyols (saccharides and hydroxy acids) according to the mechanism of self-doping by freezing negative charges in ring substituents upon complexation. This comprises the novel detection principle for reagentless affinity sensors, allowing to discriminate the specific affinity interactions from non-specific bindings.

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