AUTHOR=Zamolo Valeria A. , Modugno Gloria , Lubian Elisa , Cazzolaro Alessandro , Mancin Fabrizio , Giotta Livia , Mastrogiacomo Disma , Valli Ludovico , Saccani Alessandra , Krol Silke , Bonchio Marcella , Carraro Mauro 

TITLE=Selective Targeting of Proteins by Hybrid Polyoxometalates: Interaction Between a Bis-Biotinylated Hybrid Conjugate and Avidin

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00278

DOI=10.3389/fchem.2018.00278

ISSN=2296-2646

ABSTRACT=<p>The Keggin-type polyoxometalate [γ-SiW<sub>10</sub>O<sub>36</sub>]<sup>8−</sup> was covalently modified to obtain a bis-biotinylated conjugate able to bind avidin. Spectroscopic studies such as UV-vis, fluorimetry, circular dichroism, coupled to surface plasmon resonance technique were used to highlight the unique interplay of supramolecular interactions between the homotetrameric protein and the bis-functionalized polyanion. In particular, the dual recognition mechanism of the avidin encompasses (i) a complementary electrostatic association between the anionic surface of the polyoxotungstate and each positively charged avidin subunit and (ii) specific host-guest interactions between each biotinylated arm and a corresponding pocket on the tetramer subunits. The assembly exhibits peroxidase-like reactivity and it was used in aqueous solution for L-methionine methyl ester oxidation by H<sub>2</sub>O<sub>2</sub>. The recognition phenomenon was then exploited for the preparation of layer-by-layer films, whose structural evolution was monitored <italic>in situ</italic> by ATR-FTIR spectroscopy. Finally, cell tracking studies were performed by exploiting the specific interactions with a labeled streptavidin.</p>