Conjugation effects of various linkers on Gd(III) MRI contrast agents with Dendrimers: Optimizing the Hydroxypyridinonate (HOPO) Ligands with Nontoxic, Degradable Esteramide (EA) dendrimers for high relaxivity

William C. Floyd, Piper J. Klemm, Danil E. Smiles, Ayano C. Kohlgruber, Valérie C. Pierre, Justin Lee Mynar, Jean Frechet, Kenneth N. Raymond

Research output: Contribution to journalArticlepeer-review

85 Scopus citations

Abstract

One essential requirement for more sensitive gadolinium-based MRI contrast agents is to slow the molecular tumbling of the gadolinium(III) ion, which increases the gadolinium's relaxivity (i.e., its ability to speed up the NMR relaxation of nearby water molecules). One route to this is through conjugation to high-molecular-weight polymers such as dendrimers. In this work, amine-functionalized TREN-bis(1,2-HOPO)-TAM-ethylamine and TREN-bis(1-Me-3,2- HOPO)-TAM-ethylamine ligands have been synthesized and attached to biocompatible 40 kDa esteramide (EA)- and poly-l-lysine (PLL)-based dendrimers capable of binding up to eight gadolinium complexes. These conjugates have T1 relaxivities of up to 38.14 ± 0.02 mM-1 s-1 per gadolinium at 37 °C, corresponding to relaxivities of up to 228 mM -1 s-1 per dendrimer molecule. This relaxivity expressed on a "per Gd" basis is several times that of the small-molecule complexes and an order of magnitude higher than that of current commercial agents. Because of their high performance and low toxicity, these macromolecules may constitute an attractive complement to currently available gadolinium(III)-based contrast agents.

Original languageEnglish (US)
Pages (from-to)2390-2393
Number of pages4
JournalJournal of the American Chemical Society
Volume133
Issue number8
DOIs
StatePublished - Mar 2 2011

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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