Photo-Responsive Self-Assembly of Plasmonic Magnetic\nJanus Nanoparticles

Abstract

Stimuli-responsive\nself-assembly of nanoparticles is a versatile\napproach for the bottom-up fabrication of adaptive and functional\nnanomaterials. For this purpose, anisotropic building blocks are of\nparticular importance due to the unique shapes and structures that\ncan be obtained upon self-assembly. Here, we demonstrate the photo-responsive\nself-assembly of plasmonic magnetic “dumbbell” Janus\nnanoparticles (Au–Fe₃O₄) <i>via</i> the host–guest interaction of the supramolecular host cyclodextrin\nand the molecular photoswitch arylazopyrazole. We developed efficient\nligand exchange procedures that enable the introduction of functional\nligands, respectively, to the surface of the gold or magnetite core\nof the dumbbell. Our results indicate that distinct nanoparticle superstructures\narise in aqueous solutions if nanoparticle aggregation is crosslinker-induced\nor self-induced and that the reversible formation and fragmentation\nof the superstructures can be modulated with light.