Nanoparticles functionalized with phenylboronic acid for the potentiometric detection of saccharides

We have proposed a concept for the analytical application of modified gold nanoparticles in potentiometric sensors. The main idea is to embed modified gold nanoparticles as receptor units during electropolymerization into a polymeric matrix which should serve as a transducer of the potentiometric signal. The concept was verified using a model system based on gold nanoparticles modified with mercaptophenylboronic acid (MPBA–AuNPs) as a receptor of saccharides in a pH-sensitive polymer matrix, namely polyaniline (PANI). The determination of saccharides, in particular d-glucose, is based on the determination of released protons as products of the reaction between mercaptophenylboronic acid and saccharides. Differential pulse voltammetry showed that approximately 33% of the MPBA–AuNPs present in the polymerization mixture were built into the PANI polymeric film. The absorption and reflectivity spectra confirmed the recognition process occurring between mercaptophenylboronic acid and d-glucose inside the pH-sensitive polymeric matrix. A potentiometric response of MPBA–AuNP-modified PANI electrodes towards d-glucose in the concentration range from 0.31 up to 33 mM with a sensitivity of + 47 mV/decade was verified. The MPBA–AuNP-modified PANI film can be considered to be a saccharide-sensitive receptor layer exhibiting an indirect mechanism of signal generation.

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