Multifunctional particles: Magnetic nanocrystals and gold nanorods coated with fluorescent dye-doped silica shells

Abstract

Multifunctional colloidal core-shell nanoparticles of magnetic nanocrystals (of iron oxide or FePt) or gold nanorods encapsulated in silica shells doped with the fluorescent dye, Tris(2,2′-bipyridyl) dichlororuthenium(II) hexahydrate (Rubpy) were synthesized. The as-prepared magnetic nanocrystals are initially hydrophobic and were coated with silica using a microemulsion approach, while the as-prepared gold nanorods are hydrophilic and were coated with silica using a Stöber-type of process. Each approach yielded monodisperse nanoparticles with uniform fluorescent dye-doped silica shells. These colloidal heterostructures have the potential to be used as dual-purpose tagsexhibiting a fluorescent signal that could be combined with either dark-field optical contrast (in the case of the gold nanorods), or enhanced contrast in magnetic resonance images (in the case of magnetic nanocrystal cores). The optical and magnetic properties of the fluorescent silica-coated gold nanorods and magnetic nanocrystals are reported.

One‐Pot Synthesis of Functional Helicoidal Hybrid Organic–Inorganic Nanofibers with Periodically Organized Mesoporosity

“…The position of the surfaceplasmon band completely agrees with the Mie theory and other experimental results found in the literature, [63][64][65][66][67][68][69][70] and shows a characteristic blue-shift behavior when the nanoparticles become smaller. Moreover, highly flexible nanocomposite membranes were prepared by dispersing up to 60% of Au@SiO 2 nanofibers characterized by different sizes of gold particles in polymer solution.…”

Synthesis, microstructure and magnetic properties of Fe3Si0.7Al0.3@SiO2 core–shell particles and Fe3Si/Al2O3 soft magnetic composite core

“…Besides, silica coating techniques have been also used to prepared soft magnetic composites [14][15][16]. SiO 2 is commonly used as surfaced shell of magnetic core-shell nanoparticles because of its good chemical inertness, high suspension stability and non-toxicity [16][17][18][19][20][21][22][23][24]. In recent years, silica-coated iron particles have also been investigated as a novel kind of SMCs by many researchers [9,14,15], while few studies have been carried out for the FeSiAl-based soft magnetic materials.…”

Luminescent magnetic particles: structures, syntheses, multimodal imaging, and analytical applications

“…As a consequence, most metallic nanoparticles in LuMaPs are protected by a matrix which should reliably avoid the contact of the metallic core with the biological material. The most prominent metals and metal alloys used in LuMaPs are FeCo [102,139], FePt [63,96,109,138,140], iron or steel [92,93,141], Co [60], and BaFe [47]. An interesting approach for the protection of metallic nanoparticles was commercialized by TurboBeads Inc. not long ago (www.turbobeads.com).…”