ABSTRACT
Bifunctional Au-Fe3O4 nanoheterodimers were synthesized by thermally decomposing Fe(III)oleate on gold nanoparticles followed by functionalizing with tiron, 2,3-dihydroxybenzoic acid, or caffeic acid. These catechol derivatives are antioxidative and thus are predicted to function as superoxide scavengers. In particular, caffeic acid lost its antioxidant capacity, although it was covalently linked through its carboxyl moiety to the Fe3O4 surface. Tiron was shown to bind via its catechol group to the Au-Fe3O4 nanoheterodimers, and 2,3-dihydroxybenzoic was just physisorbed between the oleic acid surface structures. Caffeic-acid stabilized Au-Fe3O4 nanoheterodimers turned out to act as X-ray protector in healthy cells but as X-ray enhancing agents in cancer cells. Furthermore, these functionalized Au-Fe3O4 nanoheterodimers were found to inhibit the migratory capacity of the cancer cells.
Subject(s)
Caffeic Acids , Ferrosoferric Oxide , Free Radical Scavengers , Gold , Nanostructures , Neoplasms , Radiation-Protective Agents , Caffeic Acids/chemistry , Caffeic Acids/pharmacology , Ferrosoferric Oxide/chemistry , Ferrosoferric Oxide/pharmacology , Free Radical Scavengers/chemistry , Free Radical Scavengers/pharmacology , Gold/chemistry , Gold/pharmacology , Humans , MCF-7 Cells , Nanostructures/chemistry , Nanostructures/therapeutic use , Neoplasms/metabolism , Neoplasms/pathology , Neoplasms/radiotherapy , Radiation-Protective Agents/chemistry , Radiation-Protective Agents/pharmacology , X-RaysABSTRACT
Snowman-shaped Au-Fe3O4 nanoheterodimers were synthesized by thermal decomposition of iron oleate on presynthesized Au nanoparticles. Subsequently performed ligand exchange with nitrosyl tetrafluoroborate provided water solubility and enabled X-ray-induced NO release. These Au-Fe3O4 nanoheterodimers combine high- Z material with catalytically active Fe3O4 surfaces and, moreover, plasmonic properties with superparamagnetic performance. We could establish synergetic interactions between X-radiation and both the Au and Fe3O4 surfaces, which resulted in the simultaneous production of the nitric oxide radical at the Fe3O4 surface and the superoxide radical at the Au surface. The surface-confined reaction between these radicals generated peroxynitrite. This highly reactive species may cause nitration of mitochondrial proteins and lipid peroxidation and induce DNA strand breaks. Therefore, high concentrations of peroxynitrite are expected to give rise to severe cellular energetic derangements and thereupon entail rapid cell death. As providing a common platform for X-ray-induced formation of the highly reactive radical nitric oxide, superoxide, and peroxynitrite, nitrosyl tetrafluoroborate functionalized Au-Fe3O4 nanosnowmen were shown to exhibit excellent performance as X-ray-enhancing agents in radiation therapy.
