| 1. |
- Accardo, Antonella, et al.
(författare)
-
High-relaxivity supramolecular aggregates containing peptides and Gd complexes as contrast agents in MRI
- 2007
-
Ingår i: Journal of Biological Inorganic Chemistry. - : Springer Science and Business Media LLC. - 1432-1327 .- 0949-8257. ; 12:2, s. 267-276
-
Tidskriftsartikel (refereegranskat)abstract
- Mixed supramolecular aggregates, obtained by assembling together two amphiphilic monomers (C18H37)2NCO(CH2)2CO(AdOO)5-G-CCK8 (AdOO is 8-amino-3,6-dioxaoctanoic acid, CCK8 is C-terminal octapeptide of cholecystokinin) and (C18H37)2NCO(CH2)2COLys(DTPAGlu)CONH2 (DTPAGlu is N,N-bis[2-[bis(carboxyethyl)amino]ethyl]-l-glutamic acid), are characterized for their structural parameters by dynamic light scattering and for their relaxometric properties, in the absence and in the presence of 0.9 wt% NaCl. Two different aggregates (micelles and bilayer structures) are present in the absence of NaCl, while only bilayer structures are observed at physiological ionic strength. The presence of NaCl increases the ionic strength, promoting a decrease in the repulsions between the polar heads and among the aggregates in solution, thus supporting the formation of large-curvature aggregates such as bilayer structures like vesicles. In these conditions the closed, vesicular shape and the large size (hydrodynamic radius of about 300 Å) of the aggregates allow a high number of paramagnetic gadolinium complexes and bioactive peptides to be accommodated on the inner and external surfaces . The presence of the salt causes a variation in the structural arrangement of the molecules and a partial rigidification of the assembled Gd(III) complexes on the surface vesicles, reducing their internal motions and giving an approximately 15% higher relaxivity value (r 1p = 21.0 and 18.6 Mm−1 s−1 in the presence and in the absence of NaCl, respectively). The vesicles obtained, for the high relaxivity of each gadolidium complex and for the presence of a surface-exposed bioactive peptide, are very promising candidates as target-selective MRI contrast agents.
|
|
| 2. |
- Elding, Lars Ivar, et al.
(författare)
-
Detection of a Novel Intermediate in the Addition of Thiols to Osmium Carbonyl Clusters
- 1998
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 1998:24, s. 2721-2722
-
Tidskriftsartikel (refereegranskat)abstract
- Spectroscopic studies of the reaction of [Os-3(CO)(11)MeCN)] with para-thiocresol to form [Os-3(mu-H)(CO)(10)(mu-SC6H4Me-p)] indicate that the reaction proceeds via a two-step consecutive process involving the intermediate [Os-3(CO)(11)-(MeC6H4SH-p)], in which there is an agostic Os-H-S interaction.
|
|
| 3. |
- Persson, Roger, et al.
(författare)
-
Synthesis and Characterization of Triosmium Clusters Containing the Bidentate Ligand Ph2PCH2CH2SMe; Detection of an Unusual Isomerisation Reaction
- 2001
-
Ingår i: Organometallics. - : American Chemical Society (ACS). - 1520-6041 .- 0276-7333. ; 20:20, s. 4150-4160
-
Tidskriftsartikel (refereegranskat)abstract
- Diphenylphosphinoethylene methyl sulfide, Ph2PCH2CH2SMe, reacts with [Os3(CO)11(NCMe)] yielding [Os3(CO)11(Ph2PCH2CH2SMe)]. Treatment of [Os3(CO)10(NCMe)2] with 1 equiv of the P,S ligand initially yields the cluster 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)], in which the phosphine and the thioether moieties coordinate to different metal atoms of the metal triangle; addition of two or more equivalents of the ligand yields 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)] and [Os3(CO)10(Ph2PCH2CH2SMe)2]. The cluster 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)] is metastable and undergoes a slow isomerization reaction at room temperature to form 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)], in which the ligand chelates one Os atom. Computational modeling of 1,2- and 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)] indicates that the two clusters are of similar stability, with the latter isomer being of slightly lower energy. The dynamic behavior of the clusters have been investigated by variable-temperature 13C{1H} and 31P{1H} NMR, and the kinetics of the isomerization reaction have been measured. The latter indicate that the isomerization proceeds via an associative mechanism which is proposed to involve an intramolecular nucleophilic attack by the coordinated sulfur on an osmium atom. The solid state structures of [Os3(CO)11(Ph2PCH2CH2SMe)], 1,2-[Os3(CO)10(-Ph2PCH2CH2SMe)], and 1,1-[Os3(CO)10(Ph2PCH2CH2SMe)] are reported.
|
|
| 4. |
- Tesauro, Diego, et al.
(författare)
-
Peptide Derivatized Lamellar Aggregates as Target-Specific MRI Contrast Agents
- 2007
-
Ingår i: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 8:8, s. 950-955
-
Tidskriftsartikel (refereegranskat)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)2DTPAGlu-Gd, contains a very stable gadolinium complex, and the other, DSPE-PEG2000-CCK8, contains the bioactive CCK8 peptide. Samples that contained only DSPE-PEG2000-CCK8, or up to 50 % (C18)2DTPAGlu-Gd, aggregated as double-layer structures (lamellar aggregates) with a thickness of80-100 Å, as evaluated by SANS measurement and Cryo-TEM imaging. A transition to micelle formation was observed when the amount of (C18)2DTPAGlu-Gd in the aggregate was increased. These were rod-like micelles 40 Å in radius and >200 Å 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.
|
|
| 5. |
- Zhou, Jinyuan, et al.
(författare)
-
Review and consensus recommendations on clinical APT-weighted imaging approaches at 3T : Application to brain tumors
- 2022
-
Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 88:2, s. 546-574
-
Tidskriftsartikel (refereegranskat)abstract
- Amide proton transfer-weighted (APTw) MR imaging shows promise as a biomarker of brain tumor status. Currently used APTw MRI pulse sequences and protocols vary substantially among different institutes, and there are no agreed-on standards in the imaging community. Therefore, the results acquired from different research centers are difficult to compare, which hampers uniform clinical application and interpretation. This paper reviews current clinical APTw imaging approaches and provides a rationale for optimized APTw brain tumor imaging at 3 T, including specific recommendations for pulse sequences, acquisition protocols, and data processing methods. We expect that these consensus recommendations will become the first broadly accepted guidelines for APTw imaging of brain tumors on 3 T MRI systems from different vendors. This will allow more medical centers to use the same or comparable APTw MRI techniques for the detection, characterization, and monitoring of brain tumors, enabling multi-center trials in larger patient cohorts and, ultimately, routine clinical use.
|
|
