Multifunctional two-photon active silica-coated Au@MnO Janus particles for selective dual functionalization and imaging

Isabel Schick, Steffen Lorenz, Dominik Gehrig, Anna Maria Schilmann, Heiko Bauer, Martin Panthöfer, Karl Fischer, Dennis Strand, Frédéric Laquai, Wolfgang Tremel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

148 Scopus citations


Monodisperse multifunctional and nontoxic Au@MnO Janus particles with different sizes and morphologies were prepared by a seed-mediated nucleation and growth technique with precise control over domain sizes, surface functionalization, and dye labeling. The metal oxide domain could be coated selectively with a thin silica layer, leaving the metal domain untouched. In particular, size and morphology of the individual (metal and metal oxide) domains could be controlled by adjustment of the synthetic parameters. The SiO2 coating of the oxide domain allows biomolecule conjugation (e.g., antibodies, proteins) in a single step for converting the photoluminescent and superparamagnetic Janus nanoparticles into multifunctional efficient vehicles for theranostics. The Au@MnO@SiO2 Janus particles were characterized using high-resolution transmission electron microscopy (HR-)TEM, powder X-ray diffraction (PXRD), optical (UV-vis) spectroscopy, confocal laser fluorescence scanning microscopy (CLSM), and dynamic light scattering (DLS). The functionalized nanoparticles were stable in buffer solution or serum, showing no indication of aggregation. Biocompatibility and potential biomedical applications of the Au@MnO@SiO2 Janus particles were assayed by a cell viability analysis by coincubating the Au@MnO@SiO 2 Janus particles with Caki 1 and HeLa cells. Time-resolved fluorescence spectroscopy in combination with CLSM revealed the silica-coated Au@MnO@SiO2 Janus particles to be highly two-photon active; no indication for an electronic interaction between the dye molecules incorporated in the silica shell surrounding the MnO domains and the attached Au domains was found; fluorescence quenching was observed when dye molecules were bound directly to the Au domains.

Original languageEnglish (US)
Pages (from-to)2473-2483
Number of pages11
JournalJournal of the American Chemical Society
Issue number6
StatePublished - Feb 12 2014
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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