Claims
- 1. A superparamagnetic nanoparticle comprising Fe atoms and Au atoms distributed in a solid solution with no observable segregation into Fe-rich or Au-rich phases or regions.
- 2. A superparamagnetic nanoparticle comprising Fe atoms and Au atoms, wherein the nanoparticle is equiaxed with spherical morphology.
- 3. A superparamagnetic nanoparticle comprising Fe atoms and Au atoms, wherein the nanoparticle is characterized by a uniform volume magnetization.
- 4. A superparamagnetic nanoparticle comprising Fe atoms and Au atoms, wherein the nanoparticle has a saturation magnetization proportional to the number of Fe atoms in the nanoparticle.
- 5. The nanoparticle of any of claims 1 to 4 wherein the diameter of the nanoparticle is about 5 nm to about 50 nm.
- 6. The nanoparticle of any of claims 1 to 4 consisting of Fe atoms and Au atoms, wherein the Fe atom/Au atom ratio does not exceed about 1:1, i.e., Fe(50)/Au(50).
- 7. The nanoparticle of any of claims 1 to 4 wherein Fe atoms in the interior of the nanoparticle are protected from oxidation.
- 8. The nanoparticle of any of claims 1 to 4 comprising a metal core comprising the Fe atoms and the Au atoms, and a plurality of organic molecules linked to the surface of the metal core.
- 9. The nanoparticle of claim 8 wherein the organic molecules are selected so as to render the nanoparticle soluble in an organic solvent.
- 10. The nanoparticle of claim 8 wherein the organic molecules are selected so as to render the nanoparticle soluble in an aqueous environment.
- 11. The nanoparticle of claim 8 wherein the organic molecule comprises a hydrophobic polymer or a hydrophilic polymer.
- 12. The nanoparticle of claim 8 wherein the organic molecules are selected from the group consisting of a nucleic acid, a protein, a carbohydrate and a lipid.
- 13. The nanoparticle of claim 8 wherein the organic molecules comprise a sulfur atom, and wherein the organic molecules are linked to the surface of the metal core through an interaction between the Au atoms on the surface of the metal core and the sulfur atoms of the organic molecules.
- 14. The nanoparticle of claim 13 comprising a plurality of first organic molecules comprising hydrophobic or hydrophilic polymers comprising the sulfur atoms, and further comprising a plurality of second organic molecules covalently linked to the first organic molecules, such that the first organic molecules function as a chemical linker that indirectly links the second organic molecules to the surface of the metal core.
- 15. The nanoparticle of claim 14 wherein the second organic molecules are selected from the group consisting of a nucleic acid, a protein, a carbohydrate and a lipid.
- 16. A biological material comprising the nanoparticle of claim 8, wherein the biological material is selected from the group consisting of an organelle, a membrane and a cell.
- 17. The biological material of claim 16 wherein the nanoparticle is covalently or noncovalently bound to the biological material.
- 18. A population of superparamagnetic nanoparticles having uniform magnetic moments, such that the nanoparticles align their magnetic moments within an external magnetic field.
- 19. A population of superparamagnetic nanoparticles prepared by the process comprising:
evaporating a metal charge comprising Fe atoms and Au atoms using an atmospheric pressure direct current arc discharge to yield a metal vapor; contacting the metal vapor with a forced convective flow of argon gas to control particle nucleation and growth, yielding solid metal nanoparticles such that the Fe atoms and the Au atoms are distributed therein; contacting the nanoparticles with a forced convective flow helium or nitrogen gas to yield cooled nanoparticles; and bubbling the cooled nanoparticles through a liquid to yield a colloidal suspension of superparamagnetic nanoparticles.
- 20. The nanoparticle population of claim 19 wherein the liquid is aqueous sodium citrate.
- 21. The nanoparticle population of claim 19 wherein the liquid is an organic solvent.
- 22. The nanoparticle population of claim 19 wherein the liquid is mesitylene.
- 23. The nanoparticle population of claim 19 wherein the nanoparticles consist of Fe atoms and Au atoms, and wherein the Fe atom/Au atom ratio does not exceed about 1:1, i.e., Fe(50)/Au(50).
- 24. The nanoparticle population of claim 19 wherein the magnetic moment of the nanoparticles is proportional to the number of Fe atoms in the nanoparticles.
- 25. The nanoparticle population of claim 19 having a mean diameter of about 5 nm to about 50 nm and a variance of less than 50% of the mean.
- 26. The nanoparticle population of claim 19 having a mean diameter of about 5 mm to about 50 nm and a variance that has been decreased to approximately 5% of the mean by size-selective precipitation.
- 27. A method for making a population of superparamagnetic nanoparticles, the method comprising:
evaporating a metal comprising Fe atoms and Au atoms using an atmospheric pressure direct current arc discharge to yield a metal vapor; contacting the metal vapor with a forced convective flow of argon gas to control particle nucleation and growth, yielding solid metal nanoparticles such that the Fe atoms and the Au atoms are distributed therein; contacting the nanoparticles with a forced convective flow of helium or nitrogen gas to yield cooled nanoparticles; and bubbling the cooled nanoparticles through a liquid to yield a colloidal suspension of superparamagnetic nanoparticles.
- 28. The method of claim 27 wherein the liquid is aqueous sodium citrate.
- 29. The method of claim 27 wherein the liquid is an organic solvent.
- 30. The method of claim 27 wherein the liquid is mesitylene.
- 31. The method of claim 27 wherein the nanoparticles consist of Fe atoms and Au atoms, and wherein the Fe atom/Au atom ratio does not exceed about 1:1, i.e., Fe(50)/Au(50).
- 32. The method of claim 27 wherein the magnetic moment of the nanoparticles is proportional to the number of Fe atoms in the nanoparticles.
- 33. The method of claim 27 further comprising controlling the composition of the nanoparticles by controlling the composition of the metal charge of Fe atoms and Au atoms.
- 34. The method of claim 27 further comprising controlling the mean size of the particles by controlling the metal evaporation rate, the argon flow rate, or both.
- 35. The method of claim 27 wherein the rate of production of nanoparticles is on the order of grams per hour.
- 36. The method of claim 27 further comprising linking a plurality of organic molecules to the surface of the superparamagnetic nanoparticle.
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Applications Ser. No. 60/358,983, filed 22 Feb. 2002, 60/388,221, filed 13 Jun. 2002, and 60/392,192, filed 28 Jun. 2002, each of which is incorporated herein by reference in its entirety.
[0002] This application incorporates by reference U.S. patent No. ______ filed Feb. 23, 2003, entitled Magnetic Nanomaterials and Methods for Detection of Biological Materials.
Provisional Applications (3)
|
Number |
Date |
Country |
|
60392192 |
Jun 2002 |
US |
|
60388221 |
Jun 2002 |
US |
|
60358983 |
Feb 2002 |
US |