Magnetic core-shell composite particles

Oka and co-workers [14] employed the Pickering emulsion technique to fabricate core-shell composite particles, composed of copolymer poly(3HB-co-3HV) particles and magnetic iron oxide nanoparticles, for targeted drug delivery based on magnetic guidance. Iron oxide... 

There has been extensive work on core/shell nanoparticles where the core is magnetic Fe304, PbS and the shell is a polymer that provides biocompatibility and long-term stability [121]. PbS particles are formed in a Pb(AOT)2/polymer composite [122], according to whether this has an ordered layer structure or not, nanorods or spherical particles are obtained. 

Still using the same two-step procedure, monodisperse and thermoresponsive magnetic latex particles based on PNIPAM were prepared [157, 158], Anionic iron oxide nanoparticles were first adsorbed onto preformed cationic particles of various compositions [PS, poly(styrene-co-NIPAM) core-shell, or PNIPAM], The obtained heterocoagulates were then encapsulated with crosslinked PNIPAM through seeded precipitation polymaization (Fig. 24). The magnetic content varied from 6 to 23 wt%. These particles were successfiiUy used for the covalent immobilization of antibodies, and the resulting conjugates were tested as solid phases in immunoassays [159]. 

Polymers can be produced by applying the various types of polymerisation mechanism described above, i.e. all radical polymerisations including controlled polymerisation and ionic polymerisation. In addition to producing polymers with well-defined characteristics, polymerisation in heterogeneous systems can be used to produce well-defined polymer particles including very well-structured composite nanoparticles. For instance, particles with a magnetic core and nanoparticles showing a core-shell-type nanostructure can be... 

FIGURE 9.2 Illustration of particles morphology (a) hard sphere (i.e., polystyrene), (b) microgel structure (polyNIPAM), (c) core-shell like (i.e., polystyrene core-polyNIPAM shell), and (d) composite particles (i.e., hard magnetic polymer core and water soluble polymer shell). 

Coaxial spinning can also be used to form polymer-particle composite nanofibers as discussed in Chapter 6. Li et al. (2005a), in their research on decorating the interior of hoUow nanofibers with nanoparticles, used this technique very effectively. The core fluid used was a ferrofluid of magnetic iron oxide particles and the shell layer was a mixture of poly(vinyl p5u-olhdone)/ titanium isopropoxide. Extraction of the core phase of the core-shell nanofibers with octane yielded hollow, magnetically susceptible nanofibers, with their interiors decorated with oxide nanoparticles. 

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