| Sumario: | Heterostructured nanoparticles composed of metals and FeO or MnO were synthesized by thermal decomposition of mixtures of metal-oleate complexes (for the oxide component) and metal-oleylamine complexes (for the metal component). The products included flowerlike-shaped nanoparticles of Pt-FeO and Ni-FeO and snowmanlike-shaped nanoparticles of Ag-MnO and Au-MnO. Powder X-ray diffraction patterns showed that these nanoparticles were composed of face-centered cubic (fcc)-structured FeO or MnO and fcc-structured metals. The relaxivity values of the Au-MnO and Au-FeO nanoparticles were similar to those of the MnO and FeO nanoparticles, respectively. Au-FeO heterostructured narioparticles conjugated with two kinds of 12-base oligonucleotide sequences were able to sense a complementary 24-mer sequence, causing nanoparticle aggregation. This hybridization-mediated aggregation was detected by the overall size increase indicated by dynamic light scattering data, the red shift of the surface plasmon band of the Au component, and the enhancement of the signal intensity of the FeO component in T-weighted magnetic resonance imaging.
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