Novel Bifunctional Cyclic Chelator for (89)Zr Labeling-Radiolabeling and Targeting Properties of RGD Conjugates

Mol Pharm. 2015 Jun 1;12(6):2142-50. doi: 10.1021/acs.molpharmaceut.5b00128. Epub 2015 May 19.


Within the last years (89)Zr has attracted considerable attention as long-lived radionuclide for positron emission tomography (PET) applications. So far desferrioxamine B (DFO) has been mainly used as bifunctional chelating system. Fusarinine C (FSC), having complexing properties comparable to DFO, was expected to be an alternative with potentially higher stability due to its cyclic structure. In this study, as proof of principle, various FSC-RGD conjugates targeting αvß3 integrins were synthesized using different conjugation strategies and labeled with (89)Zr. In vitro stability, biodistribution, and microPET/CT imaging were evaluated using [(89)Zr]FSC-RGD conjugates or [(89)Zr]triacetylfusarinine C (TAFC). Quantitative (89)Zr labeling was achieved within 90 min at room temperature. The distribution coefficients of the different radioligands indicate hydrophilic character. Compared to [(89)Zr]DFO, [(89)Zr]FSC derivatives showed excellent in vitro stability and resistance against transchelation in phosphate buffered saline (PBS), ethylenediaminetetraacetic acid solution (EDTA), and human serum for up to 7 days. Cell binding studies and biodistribution as well as microPET/CT imaging experiments showed efficient receptor-specific targeting of [(89)Zr]FSC-RGD conjugates. No bone uptake was observed analyzing PET images indicating high in vivo stability. These findings indicate that FSC is a highly promising chelator for the development of (89)Zr-based PET imaging agents.

Keywords: 89Zr; RGD peptide; fusarinine C; positron emission tomography (PET); triacetylfusarinine C.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chelating Agents / chemistry*
  • Ferric Compounds / chemistry
  • Humans
  • Hydroxamic Acids / chemistry
  • Oligopeptides / chemistry
  • Positron-Emission Tomography
  • Radioisotopes / chemistry*
  • Zirconium / chemistry


  • Chelating Agents
  • Ferric Compounds
  • Hydroxamic Acids
  • Oligopeptides
  • Radioisotopes
  • fusigen
  • N,N',N''-triacetylfusarinine C
  • arginyl-glycyl-aspartic acid
  • Zirconium