(68)Ga/DOTA- and (64)Cu/NOTA-phthalocyanine conjugates as fluorescent/PET bimodal imaging probes

Bioconjug Chem. 2013 Sep 18;24(9):1624-33. doi: 10.1021/bc400257u. Epub 2013 Aug 26.

Abstract

In this paper, we describe the synthesis and characterization of a series of new bimodal probes combining water-soluble sulfonated zinc phthalocyanine (ZnPc) as a fluorescence imaging unit and either (68)Ga/1,4,7,10-tetraazocyclododecane-N,N'N″,N'″-tetraacetic acid (DOTA) or (64)Cu/1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) for PET imaging. The two moieties were linked through aliphatic chains of different lengths to modulate amphiphilicity. Labeling of DOTA- or NOTA-ZnPc conjugates with (68)Ga (t1/2 = 68 min) and (64)Cu (t1/2 = 12.7 h) was performed at 100 °C for 15 min with >90% efficiency for all conjugates. In vitro plasma stability assays demonstrated high stability of the (64)Cu/NOTA-ZnPc conjugate, which remained intact over a 24 h time period, and reasonably high stability of the (68)Ga/DOTA-ZnPc conjugate, which released up to 7% of free (68)Ga over a 3 h period. Based on in vitro plasma stability results, we performed biodistribution studies on two (64)Cu-labeled derivatives, which allowed us to select a single candidate for preliminary in vivo experiments. Fluorescence and PET imaging confirmed the potential of these novel conjugates to act as bimodal probes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Copper Radioisotopes / blood
  • Copper Radioisotopes / chemistry
  • Copper Radioisotopes / pharmacokinetics*
  • Fluorescent Dyes / chemistry
  • Fluorescent Dyes / pharmacokinetics*
  • Gallium Radioisotopes / blood
  • Gallium Radioisotopes / chemistry
  • Gallium Radioisotopes / pharmacokinetics*
  • Heterocyclic Compounds / blood
  • Heterocyclic Compounds / chemistry
  • Heterocyclic Compounds / pharmacokinetics*
  • Heterocyclic Compounds, 1-Ring / blood
  • Heterocyclic Compounds, 1-Ring / chemistry
  • Heterocyclic Compounds, 1-Ring / pharmacokinetics*
  • Indoles / blood
  • Indoles / chemistry
  • Indoles / pharmacokinetics*
  • Isoindoles
  • Mice
  • Mice, Nude
  • Neoplasms / diagnosis
  • Optical Imaging / methods
  • Positron-Emission Tomography / methods

Substances

  • Copper Radioisotopes
  • Fluorescent Dyes
  • Gallium Radioisotopes
  • Heterocyclic Compounds
  • Heterocyclic Compounds, 1-Ring
  • Indoles
  • Isoindoles
  • 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid
  • 1,4,7-triazacyclononane-N,N',N''-triacetic acid
  • phthalocyanine