Targeted contrast agents and methods for targeting contrast agents

Abstract

A contrast agent having a contrast protein have contrast properties and at least one targeting moiety, wherein the at least one targeting moiety is operatively linked to or incorporated within the contrast protein. Methods for targeting contrast agents and for preparing such agents are included.

1 - 20 . (canceled) 
     
     
         21 . A contrast agent comprising a modified physiological metal-binding scaffold polypeptide, wherein the scaffold polypeptide has stronger binding affinity for a paramagnetic metal ion than for a physiological metal, the contrast agent further comprising a paramagnetic metal ion bound to metal-binding domain of the polypeptide. 
     
     
         22 . The contrast agent of  claim 21 , wherein the metal-binding domain comprises a plurality of metal-specific oxygen ligands. 
     
     
         23 . The contrast agent of  claim 21 , wherein the metal-binding domain comprises continuous and non-continuous metal-binding sites. 
     
     
         24 . The contrast agent of  claim 21 , wherein the metal-binding domain comprises at least one EF-Hand or EF-like binding motif. 
     
     
         25 . The contrast agent of  claim 21 , wherein the physiological metal is calcium, manganese, copper, iron, zinc, nickel, sodium, potassium, or magnesium. 
     
     
         26 . The contrast agent of  claim 21 , wherein the paramagnetic metal ion is a lanthanide. 
     
     
         27 . The contrast agent of  claim 26 , wherein the paramagnetic metal ion is selected from the group consisting of: Gd(III), Mn(II), Fe(II), Fe(III), Co(II), Co(III), Ni(III), Mo(V), and V(IV). 
     
     
         28 . The contrast agent of  claim 26 , wherein the paramagnetic metal ion is Gd(III). 
     
     
         29 . The contrast agent of  claim 21 , further comprising a targeting moiety, wherein the targeting moiety is operatively linked to the scaffold polypeptide. 
     
     
         30 . The contrast agent of  claim 29 , further comprising a linker, wherein the linker is operatively coupled to the scaffold polypeptide and the targeting moiety. 
     
     
         31 . The contrast agent of  claim 29 , wherein the targeting moiety is operatively coupled to the C-terminus of the scaffold polypeptide. 
     
     
         32 . The contrast agent of  claim 29 , wherein the targeting moiety is operatively coupled to the N-terminus of the scaffold polypeptide. 
     
     
         33 . The contrast agent of  claim 29 , wherein the targeting moiety is inserted between the C- and N-terminus of the scaffold polypeptide. 
     
     
         34 . The contrast agent of  claim 29 , wherein the targeting moiety is operatively linked to the scaffold polypeptide by a covalent or peptide bond. 
     
     
         35 . The contrast agent of  claim 29 , wherein the targeting moiety induces endocytosis in a target cell. 
     
     
         36 . The contrast agent of  claim 29 , wherein the targeting moiety is configured to bind a cancer cell. 
     
     
         37 . The contrast agent of  claim 21 , including at least one post-translational modification. 
     
     
         38 . The contrast agent of  claim 37 , further comprising at least one polyethylene glycol (PEG) group or glucan group attached to the modified scaffold polypeptide. 
     
     
         39 . The contrast agent of  claim 21 , wherein the contrast protein has a mutation or a plurality mutations that form the metal ion binding site. 
     
     
         40 . A method of magnetic resonance imaging of a subject comprising:
 administering a recombinant protein of  claim 21  to a subject in need thereof;   allowing the recombinant protein to bind a target cell; and imaging the subject using magnetic resonance imaging.