We designed a novel Janus nanocrystal platform to control the self-assembly of nanoparticles in aqueous solutions by balancing the hydrophobic and hydrophilic moieties. Janus Au-Fe3O4 dumbbell nanocrystals (&lt; 20 nm) were synthesized with the hydrophobic ligands coated on the Au lobe and negatively charged hydrophilic ligands coated on the Fe3O4 lobe. We systematically fine-tune the lobe size ratio, surface coating, external conditions and even additional growth of Au nanocrystal domains on the Au lobe of dumbbell nanoparticles (Au-Au-Fe3O4) to harvest self-assembly structures including clusters, chains, vesicles and capsules. It was discovered that in all these assemblies the hydrophobic Au lobes preferred to stay together. The strong interparticle plasmonic coupling displayed a red-shift in surface plasmon resonance, with larger structures formed by Au-Au-Fe3O4 assembly extending into the near-infrared region. Self-assembly of Janus dumbbell nanocrystals can also be reversible under different pH values.

Synthesis and self-assembly of Janus dumbbell nanocrystals

2019 Fall National Meeting

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