Encapsulated magnetite

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... 

Landfester K, Ramfrez LP (2003) Encapsulated magnetite particles for biomedical application. J Phys Condens Matter 15 S1345-S1361... 

Emulsion polymerization techniques have also been used for the direct encapsulation of magnetic particles [113,114]. A double layer of surfactant was generally used (sodium oleate combined with sodium dodecyl benzene sulfonate). The method yielded up to 20 wt% of encapsulated magnetite into polystyrene polydis-perse latex particles. Sometimes, the formation of large amounts of coagulum could not be avoided [113a]. 

K. Landfester and L. P. Ramirez, Encapsulated magnetite for biomedical applications. Journal of Physics Condensed Matter, 15, S1345-S1361 (2003). 

Chitosan-g-NIPAM-co-N, N-dimethylacrylamide nano carrier encapsulating magnetite core (Fe O ) coupled with a drug via an acid-labile hydrazone bond It showed thermoresponsive behavior with a LCST of 38°C and faster drug release at pH 5.3. [32]... 

A) Elaboration of PLLA-based superparamagnetic nanoparticles Characterization, magnetic behavior study and in vitro relaxivity evaluation Abstract. Oleic acid-coated magnetite has been encapsulated in biocompatible magnetic nanoparticles (MNP) by a simple emulsion evaporation method. 

Fig. 17.6 Left hand side Model for the formation of magnetite in a Magnetospirillum species. L stands for an organic ligand. The oval forms represent specific Fe transport proteins, Right hand side Three magnetosomes encapsulated by a membrane (slightly modified) (Courtesy D. Schuler MPI Bremen see Schuler, 1999 A/ith permission).

Boron nitride capsules containing 10-20 nm particles of magnetite were produced by forming pellets of boron nitride magnetite in a ratio of 8 2 and arc melting the pellets in an Ar/N2 atmosphere for a few minutes. HRTEM confirmed that the magnetite particles were encapsulated in the boron nitride (Hirano et al., 1999). 

The encapsulation of magnetite particles into polystyrene particles was efficiently achieved by a miniemulsion process using oleoyl sarcosine acid [ 109] or the more efficient oleic acid as first surfactant system to handle the interface magnetite/styrene, and SDS to stabilize the interface styrene/water, thus creating a polymer-coated ferrofluid (Fig. 15b). Since the magnetite particles were very small (ca. 10 nm), each polymer particle was able to incorporate many inorganic nanoparticles. A content of 20 wt% could be incorporated in this way. 

The crosslinking of starch at the droplet interface in inverse miniemulsion leads to the formation of hydrogels. The formulation process for the preparation of crosslinked starch capsules in inverse miniemulsion is schematically shown in Fig. 10. The influence of different parameters such as the amount of starch, surfactant P(E/B-fe-EO), and crosslinker (2,4-toluene diisocyanate, TDI) on the capsule size and stability of the system were studied. The obtained capsules were in a size range of 320-920 nm. Higher amounts of starch and surfactant result in a smaller capsule size. The TEM images of crosslinked starch capsules prepared with different amount of crosslinker (TDI) are presented in Fig. 11. The nanocapsules can be employed as nanocontainers for the encapsulation of dsDNA molecules with different lengths [114] and for the encapsulation of magnetite nanoparticles. 

Kitamoto and Abe applied power ultrasonic waves (19.5 kHz, 600 W) to 300 ml of FeCh aqueous solution (pH 7.0) at 70 °C, and succeeded in encapsulating polyacrylate spheres of 250 nm diameter with magnetite ferrite coatings [49]. From TEM observations of the cross sections it was seen that the polymer spheres were covered with uniform columnar crystallites of 30-40 nm in diameter at the bottom and 60-70 nm at the top. The ultrasound waves produce OH groups on the polymer surfaces which work as ferrite nucleation sites this improves the quality of the ferrite coatings. The ferrite-encapsulated particles will greatly improve the performance of the enzyme immunoassay as a cancer test reagent. The above possible mechanism for the formation of the blue oxide is consistent with explanations in the literature for a sonochemical reaction. 

Emulsifier-free miniemulsion polymerization with [2, 2-azobis (2-amidinopropane) dihydrochloride (V50)] as initiator was also used for the encapsulation of oleic acid/magnetite nanocrystals in styrene [156, 157] or chloromethyl-styrene for further functionalization [158]. 

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