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Stability of (47)Sc-complexes with acyclic polyamino-polycarboxylate ligands.

Połosak M, Piotrowska A, Krajewski S, Bilewicz A - J Radioanal Nucl Chem (2012)

Bottom Line: We found that the ligands studied (except HBED) form strong complexes within 10 min and that the radiolabelling yield varies between 96 and 99 %.The complexes were stable in isotonic NaCl, but stability of (46)Sc-TTHA, (46)Sc-BAPTA and (46)Sc-HBED in PBS buffer was low, due to formation by Sc(3+)stronger complexes with phosphates than with the studied ligands.From the radiolabelling studies with n.c.a. (47)Sc we can conclude that the most stable complexes are formed by the 8-dentate DTPA and EGTA ligands.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nuclear Chemistry and Technology, Dorodna16, 03-195 Warsaw, Poland.

ABSTRACT

The aim of this study was to evaluate acyclic ligands which can be applied for labeling proteins such as monoclonal antibodies and their fragments with scandium radionuclides. Recently, scandium isotopes ((47)Sc, (44)Sc) are more available and their properties are convenient for radiotherapy or PET imaging. They can be used together as "matched pair" in theranostic approach. Because proteins denaturize at temperature above 42 °C, ligands which efficiently form complexes at room temperature, are necessary for labelling such biomolecules. For complexation of scandium radionuclides open chain ligands DTPA, HBED, BAPTA, EGTA, TTHA and deferoxamine have been chosen. We found that the ligands studied (except HBED) form strong complexes within 10 min and that the radiolabelling yield varies between 96 and 99 %. The complexes were stable in isotonic NaCl, but stability of (46)Sc-TTHA, (46)Sc-BAPTA and (46)Sc-HBED in PBS buffer was low, due to formation by Sc(3+)stronger complexes with phosphates than with the studied ligands. From the radiolabelling studies with n.c.a. (47)Sc we can conclude that the most stable complexes are formed by the 8-dentate DTPA and EGTA ligands.

No MeSH data available.


Structures of the ligands
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Fig2: Structures of the ligands

Mentions: As shown in Fig. 1 the kinetics of complexation at room temperature is slow, while increase of temperature to 70 °C drastically increases kinetics of labelling. Therefore, macrocyclic ligands, like DOTA, are not suitable for labelling of thermal non-resistant molecules, like proteins. In the present work, we examined selected acyclic polyamino-polycarboxylate ligands, which form complexes with scandium cations more rapidly than does DOTA. The ligands demonstrating high affinity for 3+ metal cations such as Fe3+, Ga3+ and lanthanides were selected for our studies. Structures of the ligands are presented in Fig. 2.Fig. 2


Stability of (47)Sc-complexes with acyclic polyamino-polycarboxylate ligands.

Połosak M, Piotrowska A, Krajewski S, Bilewicz A - J Radioanal Nucl Chem (2012)

Structures of the ligands
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4514464&req=5

Fig2: Structures of the ligands
Mentions: As shown in Fig. 1 the kinetics of complexation at room temperature is slow, while increase of temperature to 70 °C drastically increases kinetics of labelling. Therefore, macrocyclic ligands, like DOTA, are not suitable for labelling of thermal non-resistant molecules, like proteins. In the present work, we examined selected acyclic polyamino-polycarboxylate ligands, which form complexes with scandium cations more rapidly than does DOTA. The ligands demonstrating high affinity for 3+ metal cations such as Fe3+, Ga3+ and lanthanides were selected for our studies. Structures of the ligands are presented in Fig. 2.Fig. 2

Bottom Line: We found that the ligands studied (except HBED) form strong complexes within 10 min and that the radiolabelling yield varies between 96 and 99 %.The complexes were stable in isotonic NaCl, but stability of (46)Sc-TTHA, (46)Sc-BAPTA and (46)Sc-HBED in PBS buffer was low, due to formation by Sc(3+)stronger complexes with phosphates than with the studied ligands.From the radiolabelling studies with n.c.a. (47)Sc we can conclude that the most stable complexes are formed by the 8-dentate DTPA and EGTA ligands.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nuclear Chemistry and Technology, Dorodna16, 03-195 Warsaw, Poland.

ABSTRACT

The aim of this study was to evaluate acyclic ligands which can be applied for labeling proteins such as monoclonal antibodies and their fragments with scandium radionuclides. Recently, scandium isotopes ((47)Sc, (44)Sc) are more available and their properties are convenient for radiotherapy or PET imaging. They can be used together as "matched pair" in theranostic approach. Because proteins denaturize at temperature above 42 °C, ligands which efficiently form complexes at room temperature, are necessary for labelling such biomolecules. For complexation of scandium radionuclides open chain ligands DTPA, HBED, BAPTA, EGTA, TTHA and deferoxamine have been chosen. We found that the ligands studied (except HBED) form strong complexes within 10 min and that the radiolabelling yield varies between 96 and 99 %. The complexes were stable in isotonic NaCl, but stability of (46)Sc-TTHA, (46)Sc-BAPTA and (46)Sc-HBED in PBS buffer was low, due to formation by Sc(3+)stronger complexes with phosphates than with the studied ligands. From the radiolabelling studies with n.c.a. (47)Sc we can conclude that the most stable complexes are formed by the 8-dentate DTPA and EGTA ligands.

No MeSH data available.