Hydrophobic magnetic nanoparticles

Willner I, KatzE. ControlUng chemical reactivity at solid olution interfaces by means of hydrophobic magnetic nanoparticles. Langmuir 2006 22 1409-1419. 

Katz E, Willner I. Switching of directions of bioelectrocatalytic currents and photocurrents at electrode surfaces by using hydrophobic magnetic nanoparticles. Angew Chem Lnt Ed 2005 44 4791-4794. 

Katz E, Willner I. Hydrophobic magnetic nanoparticles induce selective bioelectrocatalysis. Chem Commun 2005 4089-4091. 

Katz E, Lioubashevski O, Willner L Magnetoswitchable single-electron charging of Au-nanoparticles using hydrophobic magnetic nanoparticles. Chem Commun 2006 1109 1111. 

Shulai Lu prepared magnetic polymeric composite particles by miniemulsion polymerization of styrene in the presence of hydrophobic magnetic nanoparticles with hexadecane (HD] as hydrophobe, 2,2 -azobisisobutyronitrile (AIBN], and sodium dodecyl sulfate (SDS] as an emulsifier or sodium p-styrenesulfonate (NaSS] as an ionic comonomer [151], The results showed that miniemulsion polymerization is an effective method for encapsulation of magnetite into a hydrophobic polymer. 

In the field of sensors, ion-binding block copolymers, which allow the formation of functionalized vesicles, could be of special interest. Vesicles sensitive to magnetic field were obtained from aqueous dispersion of hydrophobic iron oxide nanoparticles and block copolymers of PGA and PBD [272], Sachsenhofer and coworkers reported on the embedding of hydrophobic gold nanoparticles into PEO-PBD polymersomes [273]. Recently, polymer vesicles containing Ru(bpy )32+ units in the wall with a high potential for application in catalysis were introduced [274],... 

The synthesis of core-shell magnetic nanoparticles from polyacrylic acid (PAA) graft copolymers containing side chains of PEO and PPO (Fig. 5) was demonstrated by Hatton et al. [102]. Using a mixture of the polymers at a temperature of 180°C, amine-terminated PEO and PPO were coupled onto the PAA via amidation. Super-paramagnetic polymer-coated nanoparticles were synthesized by the hydrolysis and condensation of Fe(II) and Fe(III) chloride salts in the presence of PPO- or PEO-modified PAA copolymers. The extraction of organic compounds from aqueous media towards the copolymer shell of hydrophobic PPO segments can be applied in the field of water purification. 

For the encapsulation of hydrophilic magnetic nanoparticles, the surfaces have to be converted into more hydrophobic by functionalization with a surfactant having a low hydrophilic/lipophilic balance (HLB) value, with coupling agents or surface modifiers. Apart from the enhancement of the surface hydrophobicity of the inorganic particles, in some cases different reactive groups are introduced for polymerization with the hydrophobic monomer... 

Y. Zhang, L. Liu, M. Ren, C. Zhao, and W. Yang, Preparation of hollow microspheres with hydrophilic/hydrophobic asummetric surface and loading of magnetic nanoparticles, Acta Polym. Sinica, 0 (5), 502-508, 2011. 

Sun et al. [347] have synthesized the hydrophilic Fes04 nanoparticles by the modification of hydrophobic ones. Under ambient conditions, a hexane dispersion of hydrophobic Fe304 nanoparticles (about 20 mg in 0.2 mL) was added to a suspension of tetramethylammonium 11-aminoundecanoate (about 20 mg in 2 mL) in dichloromethane. The mixture was shaken for about 20 min, during which time the particles precipitated and separated using a magnet. The solvent and nonmagnetic... 

Fig. 15 T1O2 nanotubes in drug delivery system, (a) Magnetic nanoparticle filled nanotubes with attached drug (F) for magnetically guided site selective drug delivery. Release is triggered by photocatalytic chain scission upon UV irradiation. Inset an example where a blue fluorescent molecule is released from magnetically actuated nanotubes (reproduced with permission from Ref 276). (b) Amphiphilic nanotubes loaded with drugs or biomolecules which are released upon opening the hydrophobic cap with UV irradiation (reproduced with permission from Ref 202).

Reversibility of the transition renders the hydrogels attractive for sensor applications or controlled drug release. The hydrophobic core can be used to solubilize organic molecules such as fluorescent dyes or magnetic nanoparticles so... 

Figure 3.30 Synthesis route of PMO magnetic hollow spheres (a) hydrophobic, stearic acid-capped Fes04 nanoparticles in an organic phase are treated with CTAB to produce (b) water-dispersible nanoparticles, (c) Formation of FC4 vesicles leads to encapsulation of the CTAB-stabilized Fe304 nanoparticles, (d) Addition of BTME/CTAB forms the outer ethane-bridged PMO shell surrounding the vesicles. (See color insert.)...

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