Encapsulation of α-Particle-Emitting 225Ac3+ Ions Within Carbon Nanotubes.
(225)Ac(3+) is a generator of α-particle-emitting radionuclides with 4 net α-particle decays that can be used therapeutically. Targeting (225)Ac(3+) by use of ligands conjugated to traditional bifunctional chelates limits the amount of (225)Ac(3+) that can be delivered. Ultrashort, single-walled carbon nanotubes (US-tubes), previously demonstrated as sequestering agents of trivalent lanthanide ions and small molecules, also successfully incorporate (225)Ac(3+).


METHODS
Aqueous loading of both (225)Ac(3+) ions and Gd(3+) ions via bath sonication was used to construct (225)Ac@gadonanotubes ((225)Ac@GNTs). The (225)Ac@GNTs were subsequently challenged with heat, time, and human serum.


RESULTS
US-tubes internally loaded with both (225)Ac(3+) ions and Gd(3+) ions show 2 distinct populations of (225)Ac(3+) ions: one rapidly lost in human serum and one that remains bound to the US-tubes despite additional challenge with heat, time, and serum. The presence of the latter population depended on cosequestration of Gd(3+) and (225)Ac(3+) ions.


CONCLUSIONS
US-tubes successfully sequester (225)Ac(3+) ions in the presence of Gd(3+) ions and retain them after a human serum challenge, rendering (225)Ac@GNTs candidates for radioimmunotherapy for delivery of (225)Ac(3+) ions at higher concentrations than is currently possible for traditional ligand carriers.
Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas.
Michael L
ML
Matson
Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, and Weill Cornell Medical College, New York, New York; and.
Carlos H
CH
Villa
Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas Molecular Imaging Program at Stanford University, Department of Radiology, Stanford University, Stanford, California.
Jeyarama S
JS
Ananta
Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas.
Justin J
JJ
Law
Molecular Pharmacology and Chemistry Program, Memorial Sloan Kettering Cancer Center, and Weill Cornell Medical College, New York, New York; and.
David A
DA
Scheinberg
Department of Chemistry, and the Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas durango@rice.edu.
Lon J
LJ
Wilson
D000186:Actinium / Q000737:chemistry*; D000512:Alpha Particles; D002614:Chelating Agents / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry; D003952:Diagnostic Imaging; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D007477:Ions; D008024:Ligands; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry*; D016499:Radioimmunotherapy / Q000295:instrumentation* / Q000379:methods
D002614:Chelating Agents; D003287:Contrast Media; D007477:Ions; D008024:Ligands; D037742:Nanotubes, Carbon; D005682:Gadolinium; D000186:Actinium
225Ac; alpha therapy; carbon nanotube; nanotechnology