Surface Functionalization of the Metal Oxide Nanoparticles with Biologically Active Molecules Containing Phosphonate Moieties. Case Study of BaTiO3

Nanoparticles of a broad variety of main group and transition metal oxides appear to form exceptionally stable surface complexes with the ligands incorporating phosphate or phosphonate moiety. In the present work we demonstrate the formation and stability of such complexes on an example of BaTiO 3 perovskite with the aid of scanning electron microscopy/energy dispersive spectroscopy, pH-metric titration, NMR and IR spectroscopy, dynamic light scattering, ζ potential, nanoparticle tracking analysis, thermogravimetric analysis, and radiometric measurements. Application of amino phosphonic acids as surface ligands provides nanoparticles with considerable solution stability in an aqueous medium at neutral pH and especially in the presence of electrolytes. This opens broad prospects of application for the thus produced nanoparticle dispersions in the domains of nano-optics and nanomagnetism. The same effect is observed even for surface complexation with nucleotides or phosphorylated proteins, using adenosine-triphosphate (ATP) and phosphocreatine (PCr) as model compounds, permitting the production of highly stable dispersions of specifically biologically targeted nanoparticles (particles supplied with predesigned biomolecular “corona”) for use in magnetic resonance and optical imaging and even in drug delivery as supported by in vitro measurements. We have shown that the presented approach might be successfully broadened for other types of mixed metal oxide systems constituted of nanoparticles.