Magnetic particles

Abstract

Materials and methods for making small magnetic particles, e.g., clusters of metal atoms, which can be employed as a substrate for immobilizing a plurality of ligands. Also disclosed are uses of these magnetic nanoparticles as therapeutic and diagnostic reagents, and in the study of ligand-mediated interactions.

1 . A magnetic nanoparticle having a core of metal atoms, wherein the core is covalently linked to a plurality of ligands and has a diameter of less than 2.5 nm. 
     
     
         2 . The magnetic nanoparticle of  claim 1 , wherein the core comprises passive metal atoms and magnetic metal atoms. 
     
     
         3 . The magnetic nanoparticle of  claim 1 , wherein the core comprises passive metal atoms. 
     
     
         4 . The magnetic nanoparticle of  claim 2 , wherein the passive metal is gold, platinum, silver or copper and the optional magnetic metal is iron, cobalt or gadolinium. 
     
     
         5 . The magnetic nanoparticle of  claim 1 , wherein the core is formed from atoms of Au, Au/Fe, Au/Cu, Au/Gd, Au/Fe/Cu, Au/Fe/Gd or Au/Fe/Cu/Gd. 
     
     
         6 . The magnetic nanoparticle of  claim 2 , wherein the ratio of passive metal atoms to magnetic metal atoms in the core is between about 5:0 and about 2:5 
     
     
         7 . The magnetic nanoparticle of  claim 2 , wherein the ratio of passive metal atoms to magnetic metal atoms in the core is between about 5:0.1 and about 5:1. 
     
     
         8 . The magnetic nanoparticle of  claim 2 , wherein the passive metal is gold and the magnetic metal is iron. 
     
     
         9 . The magnetic nanoparticle of  claim 8 , wherein the ratio of gold atoms to iron atoms is about 5:0.1. 
     
     
         10 . The magnetic nanoparticle of  claim 8 , wherein the ratio of gold atoms to iron atoms is about 5:1. 
     
     
         11 . The magnetic nanoparticle of  claim 1 , wherein the core has a diameter of less than 2.0 nm when the core contains only passive metal atoms such as Au. 
     
     
         12 . The magnetic nanoparticle of any one of  claim 1 , wherein said ligands incorporate a lanthanide. 
     
     
         13 . The magnetic nanoparticle of  claim 12 , wherein the lanthanide is gadolinium. 
     
     
         14 . The magnetic nanoparticle of  claim 1 , wherein the nanoparticle comprises an NMR active atom. 
     
     
         15 . The magnetic nanoparticle of  claim 14 , wherein the NMR active atom is Mn +2 , Gd +3 , Eu +2 , Cu +2 , V +2 , Co +2 , Ni +2 , Fe +2 , Fe +3  or a lanthanide +3 . 
     
     
         16 . The nanoparticle of  claim 1 , wherein at least one of the ligands comprises a carbohydrate group. 
     
     
         17 . The nanoparticle of  claim 1 , wherein said ligands comprise a polysaccharide, an oligosaccharide or a monosaccharide group. 
     
     
         18 . The nanoparticle of  claim 1 , wherein said ligands comprises a glycanoconjugate. 
     
     
         19 . The nanoparticle of  claim 18 , wherein the glycanoconjugate is a glycolipid or a glycoprotein. 
     
     
         20 . The nanoparticle of  claim 1 , wherein said ligands are linked to the core via a sulphide group. 
     
     
         21 . The nanoparticle of  claim 1 , wherein the nanoparticle comprises a label. 
     
     
         22 . The nanoparticle of  claim 21 , wherein the label is a fluorescent group or a radioactive isotope or a NMR active atom. 
     
     
         23 . The nanoparticle of  claim 1 , wherein the nanoparticle comprises a peptide. 
     
     
         24 . The nanoparticle of  claim 1 , wherein the nanoparticle comprises DNA or RNA. 
     
     
         25 . The nanoparticle of  claim 1 , wherein the nanoparticle comprises a pharmaceutically active component. 
     
     
         26 . The nanoparticle of  claim 1 , wherein the ligand is capable of binding a receptor on a cell. 
     
     
         27 . The nanoparticle of  claim 1 , wherein the nanoparticle is water soluble. 
     
     
         28 . A composition comprising a population of one or more of the nanoparticles of  claim 1 . 
     
     
         29 . The composition of  claim 28  which comprises a plurality of nanoparticles having different ligand groups. 
     
     
         30 . A method for treating cancer in a patient, said method comprising introducing at least one nanoparticle into said patient and applying a high frequency magnetic field to kill cancer cells, said nanoparticle having a core of metal atoms selected from the group consisting of: gold, platinum, silver and copper atoms, the core having a diameter of less than 2.5 nm, wherein the core is covalently linked to a plurality of ligands, at least one of which comprises a carbohydrate group. 
     
     
         31 . The method of  claim 30 , wherein the core of the nanoparticle has a diameter of less than 2.0 nm and the core is formed from gold atoms. 
     
     
         32 . The method of  claim 30 , wherein the ligands are linked to the core via a sulphide group. 
     
     
         33 . The method of  claim 30 , wherein the nanoparticle is water soluble. 
     
     
         34 . The method of  claim 30 , wherein the nanoparticle further comprises a peptide, DNA or RNA. 
     
     
         35 . The method of  claim 30 , wherein the ligand comprises: a polysaccharide, an oligosaccharide, or a monosaccharide group; or a glycanoconjugate. 
     
     
         36 . The method of  claim 30 , wherein the treatment of cancer is the treatment of a tumour. 
     
     
         37 . The method of  claim 36 , wherein the nanoparticle comprises a ligand that includes a tumour-specific antigen for specifically targeting the nanoparticle to the tumour. 
     
     
         38 . The method of  claim 37 , wherein the ligand is a tumour associated antigen or tumour autocrine factor.