Micelles derivatized with octreotide as potential target-selective contrast agents in MRI

Anna Morisco, Antonella Accardo, Eliana Gianolio, Diego Tesauro, Ettore Benedetti, Giancarlo Morelli

Research output: Contribution to journalArticle

Abstract

New amphiphilic monomers (OCA-DTPAGlu and OCA-DOTA) containing, in the same molecule, three different functions: (i) the chelating agent (DTPAGlu or DOTA) able to coordinate gadolinium ion, (ii) the octreotide bioactive peptide able to target somatostatin receptors, and (iii) a hydrophobic moiety with two 18-carbon atoms alkyl chains have been designed and synthesized by solid-phase methods. The novel amphiphilic monomers aggregate, in water solution, giving stable micelles at very low concentration (cmc values of 2.3 × 10-6 mol kg-1 and 2.5 × 10-6 mol kg-1 for OCA-DTPAGlu and OCA-DOTA, respectively) as confirmed by fluorescence spectroscopy. Fluorescence studies and circular dichroism experiments indicate, for the two compounds as well as for their gadolinium complexes (OCA-DOTA(Gd) and OCA-DTPAGlu(Gd)), the complete exposure of octreotide on the micelle surface, and the predominant presence of an antiparallel β-sheet peptide conformation characterized by a β-like turn. The high relaxivity value (r1p = 13.9mM-1 s-1 at 20 MHz and 25 °C), measured for micelles obtained by the gadolinium complex OCA-DTPAGlu(Gd), indicates these aggregates as promising target-selective magnetic resonance imaging (MRI) contrast agents.

Original languageEnglish
Pages (from-to)242-250
Number of pages9
JournalJournal of Peptide Science
Volume15
Issue number3
DOIs
Publication statusPublished - 2009

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Keywords

  • Fluorescence spectroscopy and circular dichroism
  • Micelles
  • MRI contrast agent
  • Octreotide

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Molecular Medicine
  • Structural Biology
  • Organic Chemistry
  • Drug Discovery
  • Pharmacology

Cite this

Morisco, A., Accardo, A., Gianolio, E., Tesauro, D., Benedetti, E., & Morelli, G. (2009). Micelles derivatized with octreotide as potential target-selective contrast agents in MRI. Journal of Peptide Science, 15(3), 242-250. https://doi.org/10.1002/psc.1087