title: Peptide derivatized lamellar aggregates as target-specific MRI contrast agents.
abstract: The relaxivity behaviour and the structural characterization of new supramolecular aggregates (bilayer structures and micelles) obtained by combining two different amphiphilic monomers are reported. One monomer, (C18)(2)DTPAGlu-Gd, contains a very stable gadolinium complex, and the other, DSPE-PEG(2000)-CCK8, contains the bioactive CCK8 peptide. Samples that contained only DSPE-PEG(2000)-CCK8, or up to 50 % (C18)(2)DTPAGlu-Gd, aggregated as double-layer structures (lamellar aggregates) with a thickness of approximately 80-100 A, as evaluated by SANS measurement and Cryo-TEM imaging. A transition to micelle formation was observed when the amount of (C18)(2)DTPAGlu-Gd in the aggregate was increased. These were rod-like micelles approximately 40 A in radius and >200 A in length. The proton relaxivities for both lamellar aggregates and rod-like micelles were the same (17.2 mM(-1) s(-1)), although the values were the results of different combinations of local and global contributions. The in vitro target selectivity of aggregates that contained the CCK-8 peptide was demonstrated by using nuclear medicine techniques.
authors.affiliation: Department of Biological Sciences, CIRPeB University of Naples, Federico II and IBB CNR, Via Mezzocannone 16, Naples, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Tesauro
authors.forename: Antonella
authors.initials: A
authors.lastname: Accardo
authors.forename: Eliana
authors.initials: E
authors.lastname: Gianolio
authors.forename: Luigi
authors.initials: L
authors.lastname: Paduano
authors.forename: José
authors.initials: J
authors.lastname: Teixeira
authors.forename: Karin
authors.initials: K
authors.lastname: Schillén
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Morelli
mesh_terms: D002766:Cholecystokinin / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008823:Micelles; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010316:Particle Size; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013329:Structure-Activity Relationship
chemical_list: D003287:Contrast Media; D046911:Macromolecular Substances; D008823:Micelles; D009942:Organometallic Compounds; D010446:Peptide Fragments; D010455:Peptides; C410885:cholecystokinin 8; D002766:Cholecystokinin; D005682:Gadolinium