Encapsulated magnetic particles

Magnetic fluids are stable dispersions of ultrafine magnetic particles or encapsulated magnetic particles in an organic or aqueous carrier medium. The stabihza-tion of these particles can be achieved by surfactants which hinder the particles from flocculation or sedimentation. In ideal cases, the particles also keep their stability under the exposition of magnetic fields. 

Cationic PNIPAM-covered magnetic particles Hetero coagulation of iron oxide nanoparticles onto cationic particles. Encapsulation of preformed particles by polymerization of NIPAM, BAM and AEMH 300-1000 nm Superparamag-netic, bioreactive particles. Temperature, salinity and pH sensitive [10,18,19]... 

In an interesting variation of the technology. Law et al, (L2) described a liposome-based TSH assay in which the liposomal membrane surface contained covalently attached antibodies, and a modified membrane-impermeable acridinium ester derivative was encapsulated inside the vesicles. A normal sandwich assay was conducted using magnetic particles as the solid phase and antibody-sensitized liposomes as the label. The total assay time was 5 min, compared with the normal 2.5 hr, and showed superior sensitivity. 

Zhang QY, Xie G, Zhang HP, et al. (2(X)7) Encapsulation of magnetic particles via miniemulsion polymerization of styrene. II. Effect of some parameters on the polymerization of styrene. J Appl Polym Sci 105 3525-3530... 

Ramtrez LP, Landfester K (2003) Magnetic polystyrene nanoparticles with a high magnetite content obtained by miniemulsion processes. Macromol Chem Phys 204 22-31 Landfester K, Ramirez LP (2003) Encapsulated magnetite particles for biomedical application. J Phys Condens Matter 15 S1345-S1361... 

In a quest for different applications various numbers of polymers have been chosen to prepare encapsulated and functionalized magnetic particles by soap-free emulsion polymerization. Examples are amide- and carboxyl-functionalized magnetic latex for protein immobilization [156], and thermally sensitive and carboxyl-functionalized particles for antibody purification [157], bioprocesses... 

The effect of the amount of surfactant SDS, hydrophobe hexadecane, iron oxide magnetic particles, MAA and non-ionic cellulose ether, hydroxyethylcellulose, on the magnetic latex morphology, surface quality and size distribution was studied by Forcada et al. for the encapsulation of magnetic particles by miniemulsion polymerization of St. Optimal conditions were 2-3% of SDS, 9-12% of hexadecane, 10% of iron oxide and 2% of HEC, relative to the total amount of St and iron oxide [177]. 

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