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 language | English |
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Pages (from-to) | 242-250 |
Number of pages | 9 |
Journal | Journal of Peptide Science |
Volume | 15 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2009 |
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