Layer-by-Layer synthesis and tunable optical properties of hybrid magnetic–plasmonic nanocomposites using short bifunctional molecular linkers

Abstract

Spurred by research in magnetoplasmonics, plasmon-enhanced magneto-optical effects and active plasmonics, the demand for hybrid magnetic-plasmonic nanoparticle-based materials of optical quality is high. Currently used synthesis methods involve possibly interfering polymer media or polyelectrolyte interlayers, grooved supports or non-transparent substrates. To obtain homogeneous, partially transparent and polymer/polyelectrolyte-free magnetic-plasmonic nanocomposites with angle-independent optical properties, we produced hybrid gold-magnetite and silver-magnetite nanocomposites by a novel Layer-by-Layer synthesis using short bifunctional molecular linkers on glass substrates. Resulting nanocomposites had high nanoparticle filling fractions and showed tunability of the plasmon wavelength over a very broad spectral range by changing composite thickness through the number of added nanoparticle layers. The angle-independence of optical properties and the abilities to switch the plasmonic material and to tune the plasmon resonances of the magnetic-plasmonic composites make these materials a unique platform for magnetoplasmonic research.

Optical properties of magnetic-plasmonic nanoparticle multilayers

“…9 SFM measurements yielded a thickness of the first double layer of about 13.2 nm and for each added NDL the total structure became about 7.3 nm thicker.…”

“…[9][10][11][12] Au-Fe 3 O 4 nanocomposites with different numbers of nanoparticle double layers (NDLs), which are one gold and one iron oxide nanoparticle layer combined were synthesized. Magnetic-plasmonic nanoparticle multilayers fabricated using this protocol are of optical quality, homogeneous without visible aggregates and a variable thickness.…”

“…Because of the polymer-/polyeletrolyte-free fabrication method, such nanoparticle multilayers have large nanoparticle filling fractions. 9 To gain insight in the origin of the optical properties of these magnetic-plasmonic materials and vice versa to learn more about the structural properties through a thorough knowledge of the optical properties, a joint theoretical-experimental approach was adopted.…”

Multifunctional iron oxide nanoparticles for biomedical applications

“…[1][2][3][4] If the NP's size ranges between 5 and 25nm, magnetite (Fe 3 O 4 ) exhibits superparamagnetic behavior. This interesting property combines the convenient handling of a paramagnetic material (no net moment without any external magnetic field) with the large magnetic moment of a ferromagnet.…”

Selective protein purification by PEG–IDA-functionalized iron oxide nanoparticles

“…[1][2][3][4][5][6][7] They have a unique magnetic behavior called superparamagnetism, which is the absence of a net magnetic moment without an applied magnetic eld (similar to a paramagnet), while having a magnetic susceptibility comparable to a ferromagnetic material. Iron oxide particles (such as magnetite) are frequently used in hyperthermia, magnetic resonance imaging, optical or drug carrier experiments.…”