Resumen
[0001] The invention relates to nanoparticles of noble metals, having a controlled microstructure which leads to the appearance of ferromagnetic behaviour in said nanoparticles, thereby enabling the use of very small magnets (< 5 nm) in a range in which standard ferromagnetic metals behave as superparamagnetic entitles (disappearance of hysteresis cycle). The inventive nanoparticles can be used, for example, to reduce the dimensions in magnetic recordings, as well as in biomedicine as tools for biomolecule recognition, nuclear magnetic resonance imaging, drug-release control or hypothermia treatments.
Reivindicaciones
1. Magnetic nanoparticles of noble metals non-magnetic in the mass state of size less than 5 nm comprising: a) a core formed from a noble metal and b) an anisotropic crust formed from compounds containing at least one metal-sulphur covalent bond. 2. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claim 1, characterised in that the noble metal for the core is Au, Pd, Pt, Ag or any other metal non-ferromagnetic in the mass state. 3. Magnetic nanoparticles of noble metals according to claims 1 and 2, characterised in that the size of the nanoparticles lies between 1.0 and 2.0 nm, preferably between 1.2 and 1.4 nm. 4. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claims 1-3, characterised in that when the core is formed from Au, the anisotropic crust contains Au-S compounds and Au-S-R compounds in proportions between 1/1000 and 1000/1 (Au-S/Au-S-R). 5. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claims 1-3, characterised in that when the core is formed from Pd, the anisotropic crust contains Pd-S compounds and Pd-S-R compounds in proportions between 1/1000 and 1000/1 (Pd-S/Pd-S-R). 6. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claims 4 and 5, characterised in that R is an aliphatic chain or an aliphatic chain in turn joined to other molecules, in particular proteins or other biomolecules, R in turn being able to contain a marker, a fluorescent group or a radioactive isotope. 7. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claims 1-6, characterised in that the nanoparticles display a ferromagnetic behaviour. 8. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claim 7, characterised in that the nanoparticles display a ferromagnetic behaviour with low coercive field. 9. Magnetic nanoparticles of noble metals non-magnetic in the mass state according to claim 1-6, characterised in that the nanoparticles display a paramagnetic behaviour. 10. Process for preparation of magnetic nanoparticles according to claims 1-9, comprising the reaction of a precursor of the non-magnetic noble metal with a thiol derivative of general formula HS-R in stoichiometric excess and in the presence of a reducing agent. 11. Process for preparation of magnetic nanoparticles according to claim 10, characterised in that when the non-magnetic noble metal is gold the precursor is prepared by means of reaction of tetrachloroauric acid with any quaternary ammonium salt in stoichiometric excess. 12. Process for preparation of magnetic nanoparticles according to claim 10, characterised in that when the non-magnetic noble metal is palladium the precursor is prepared by means of reaction of any palladium salt, in particular nitrate, sulphate or chloride, with any quaternary ammonium salt in stoichiometric excess. 13. Use of magnetic nanoparticles according to claims 1-9 for Increasing the density of information in a magnetic recording. 14. Use of magnetic nanoparticles according to claims 1-9 in a device for the controlled release of drugs. 15. Use of magnetic nanoparticles according to claims 1-9 for hyperthermia treatment. 16. Use of magnetic nanoparticles according to claims 1-9 for improving the imaging in nuclear magnetic resonance. 17. Use of magnetic nanoparticles according to claims 1-9 as biosensors. 18. Use of magnetic nanoparticles according to claims 1-9 in magnetic printing. 19. Use of magnetic nanoparticles according to claims 1-9 in magneto-optical applications. 20. Use of magnetic nanoparticles according to claims 1-9 in coding applications. 21. A system which will contain a population of one or more of the nanoparticles according to claims 1 to 9. 22. A system according to claim 20 which will contain a plurality of nanoparticles containing different functional groups.
