Hybrid, Silica-Coated, Janus-Like Plasmonic-Magnetic Nanoparticles

Hybrid plasmonic-magnetic nanoparticles possess properties that are attractive in bioimaging, targeted drug delivery, <i>in vivo</i> diagnosis and therapy. The stability and toxicity, however, of such nanoparticles challenge their safe use today. Here, biocompatible, SiO₂-coated, Janus-like Ag/Fe₂O₃ nanoparticles are prepared by one-step, scalable flame aerosol technology. A nanothin SiO₂ shell around these multifunctional nanoparticles leaves intact their morphology, magnetic and plasmonic properties but minimizes the release of toxic Ag⁺ ions from the nanosilver surface and its direct contact with live cells. Furthermore, this silica shell hinders flocculation and allows for easy dispersion of such nanoparticles in aqueous and biological buffer (PBS) solutions without any extra functionalization step. As a result, these hybrid particles exhibited no cytotoxicity during bioimaging and remained stable in suspension with no signs of agglomeration and sedimentation or settling. Their performance as biomarkers was explored by selectively binding them with live tagged Raji and HeLa cells enabling their detection under dark-filed illumination. Therefore, these SiO₂-coated Ag/Fe₂O₃ nanoparticles do not exhibit the limiting physical properties of each individual component but retain their desired functionalities facilitating thus, the safe use of such hybrid nanoparticles in bio-applications.