Discrete magnetic nanoparticles
Discrete magnetic nanoparticles synthesized using a layer-by-layer technique are disclosed. The nanoparticles contain a magnetic core having a large magnetic moment, a plurality of layers and an exterior coating. The nanoparticles have utility in a wide range of biological and bioanalytical applications.
1. A nanoparticle comprising
a magnetic core particle coated with at least one hydrophilic coating,
a plurality of layers coupled to the hydrophilic coating, wherein the plurality of layers comprises alternating layers of at least one polycationic layer and at least one polyanionic layer, and
a protective exterior coating,
wherein the magnetic particle has a diameter of at least 100 nm and exhibits a magnetic moment of at least about 1.5×10 −13 emu.
2. The nanoparticle of claim 1 , wherein the plurality of layers comprise at least one of a polystyrene, a poly(allylamine), a poly(lysine), an alginate, hyaluronan, a poly(glutamic acid), a poly(lactic acid), a poly(acrylic acid), a poly(methacrylic acid), chitosan, a poly(ethylenimine), a diallyldimethylammonium halide, N-methyl-N-vinylacetamide, a poly(vinyl sulfate), a poly(vinyl sulfonate), a poly(3-thiophene acetic acid), a poly(maleic acid), or a poly(ethylene).
3. The nanoparticle of claim 1 , wherein the hydrophilic coating comprises at least one of citric acid, dimercaptosuccinic acid, poly(ethyleneimine), poly(allylamine) or polystyrene sulfonate.
4. The nanoparticle of claim 1 , wherein the protective exterior coating comprises silica or titania.
5. The nanoparticle of claim 1 , wherein the core particle comprises a zinc ferrite cubic particle having a minimum edge length of at least about 100 nm, and wherein the plurality of layers comprises at least six layers.
6. The nanoparticle of claim 1 , wherein the average diameter of the nanoparticle is between about 100 nm and about 300 nm.
7. A method for preparing a nanoparticle, comprising:
depositing a hydrophilic coating on a magnetic core particle to form a coated particle,
depositing a plurality of layers on the coated particle to form a layer-coated particle, wherein the plurality of layers comprises alternating layers of at least one polycationic layer and at least one polyanionic layer, and
depositing a protective coating on the exterior of the layer-coated particle to form the nanoparticle,
wherein the magnetic particle has a diameter of at least 100 nm and exhibits a magnetic moment of at least about 1.5×10 −13 emu.
8. The method of claim 7 , wherein the plurality of layers comprise at least one of a polystyrene, a poly(allylamine), a poly(lysine), an alginate, hyaluronan, a poly(glutamic acid), a poly(lactic acid), a poly(acrylic acid), a poly(methacrylic acid), chitosan, a poly(ethylenimine), a diallyldimethylammonium halide, N-methyl-N-vinylacetamide, a poly(vinyl sulfate), a poly(vinyl sulfonate), a poly(3-thiophene acetic acid), a poly(maleic acid), or a poly(ethylene).
9. The method of claim 7 , wherein the exterior coating comprises silica or titania.
10. A nanoparticle comprising
a magnetic core particle comprising a zinc ferrite cubic particle having a minimum edge length of at least about 100 nm,
a plurality of layers comprising alternating layers of at least one polycationic layer and at least one polyanionic layer, and
protective exterior coating,
wherein the magnetic particle exhibits a magnetic moment of at least about 1.5×10 −13 emu and wherein the plurality of layers comprises at least six layers.
11. The nanoparticle of claim 10 , wherein the plurality of layers comprise at least one of a polystyrene, a poly(allylamine), a poly(lysine), an alginate, hyaluronan, a poly(glutamic acid), a poly(lactic acid), a poly(acrylic acid), a poly(methacrylic acid), chitosan, a poly(ethylenimine), a diallyldimethylammonium halide, N-methyl-N-vinylacetamide, a poly(vinyl sulfate), a poly(vinyl sulfonate), a poly(3-thiophene acetic acid), a poly(maleic acid), or a poly(ethylene).
12. The nanoparticle of claim 10 , wherein the core particle is further coated with at least one hydrophilic coating and the plurality of layers is coupled to the hydrophilic coating.
13. The nanoparticle of claim 12 , wherein the hydrophilic coating comprises at least one of citric acid, dimercaptosuccinic acid, poly(ethyleneimine), poly(allylamine) or polystyrene sulfonate.
14. The nanoparticle of claim 10 , wherein the exterior coating comprises silica or titania.
15. The nanoparticle of claim 10 , wherein the average diameter of the nanoparticle is between about 100 nm and about 300 nm.