A plethora of new inorganic nanoparticles has appeared in the last years boosting the development of a wide variety of technological areas. Among them, noble metal nanoparticles are prominent examples as they allow manipulation and control of light through their plasmonic properties. Another recognized type is the one formed by ferro- and ferrimagnetic materials, such as iron oxide, that at small size shows superparamagnetism enabling its manipulation with external magnetic fields and the subsequent re-dispersion in its absence. Janus nanoparticles (those with two chemically different regions) have emerged as exceptional candidates for many applications. Their strong interaction with interfaces has been used in applications ranging from emulsified nanoreactors to filtering nanomembranes. Their unique anisotropy has been applied in antireflection surfaces, electronic displays, nanojets, or just as building block for more complex molecular colloids and supracrystals. They also offer extraordinary potential in biomedicine where they can mimic natural biomolecules, produce directed interactions with cell membranes, and offer selected regions with high number of interaction points while keeping multiple functionalities. Here, we report the synthesis and characterization of novel Janus Au-Fe3O4 star-sphere nanoparticles. They show superparamagnetism and a high plasmonic absorption at the near-IR (first biological transparency window). Different versions of nanoparticles have been synthesized through two consecutive seed-mediated-growth steps by varying the precursor to seed ratios. The obtained synthesized nanoparticles are highly uniform and show good colloidal stability in water, PBS, and cell media. Their combination of properties makes them highly versatile and potential candidates to many applications. Here, we report on their characterization in analytical sensing using surface-enhanced Raman spectroscopy (SERS), plasmonic hyperthermia, and multimodal imaging including cell imaging in dark and bright field, multiplexed SERS mapping, magnetic resonance imaging (MRI) computed tomography (CT) and photoacoustic imaging. The synthesized nanoparticles have shown to be excellent nanoprobes in all techniques with clear advantages provided by the Janus configuration. These results open the doors to their use in many applications, including the generation of integrated nanodevices for a multi-angle approach in well controlled and efficient biomedical applications.

Janus Fe3O4-Au magnetic-plasmonic nanoparticles for sensing, hyperthermia, and molecular imaging

256th National Meeting (2018)

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