Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate
Autor(a) principal: | |
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Data de Publicação: | 2006 |
Outros Autores: | , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/1822/4469 |
Resumo: | In this paper we report the synthesis and the characterization of the novel ligand H5EPTPA-C16 ((hydroxymethylhexadecanoyl ester)ethylenepropylenetriaminepentaacetic acid). This ligand was designed to chelate the GdIII ion in a kinetically and thermodynamically stable way while ensuring an increased water exchange rate (kex) on the GdIII complex due to steric compression around the water binding site. The attachment of a palmitic ester unit to the pendant hydroxymethyl group on the ethylenediamine bridge yields an amphiphilic conjugate that forms micelles in aqueous solution with a long tumbling time (R). The critical micelle concentration (CMC = 0.34 mM) of the amphiphilic [Gd(EPTPA-C16)(H2O)]2- chelate was determined by variable concentration proton relaxivity measurements. A global analysis of the data obtained in variable temperature and multiple field 17O NMR, and 1H NMRD measurements allowed the determination of parameters governing relaxivity for [Gd(EPTPA-C16)(H2O)]2-; this is the first time that paramagnetic micelles with optimized water exchange are investigated. The water exchange rate was found to be kex298 = 1.7×108 s-1, very similar to that previously reported for the nitrobenzyl derivative [Gd(EPTPA-bz-NO2)(H2O)]2- (kex298 = 1.5×108 s-1). The rotational dynamics of the micelles was analysed using the Lipari-Szabo approach. The micelles formed in aqueous solution show a considerable flexibility, with a local rotational correlation time of the GdIII segments, lO298 = 330 ps, being much shorter than the global rotational correlation time of the supramolecular aggregates, gO298 = 2100 ps. This internal flexibility of the micelles is responsible for the only limited increase of the proton relaxivity observed on micelle formation (r1 = 22.59 mM-1s-1 for the micelles vs. 9.11 mM-1s-1 for the monomer chelate (20 MHz; 25°C)). |
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Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rateGadoliniumImaging agentsMicellesSteric compressionWater exchangeMRICMCScience & TechnologyIn this paper we report the synthesis and the characterization of the novel ligand H5EPTPA-C16 ((hydroxymethylhexadecanoyl ester)ethylenepropylenetriaminepentaacetic acid). This ligand was designed to chelate the GdIII ion in a kinetically and thermodynamically stable way while ensuring an increased water exchange rate (kex) on the GdIII complex due to steric compression around the water binding site. The attachment of a palmitic ester unit to the pendant hydroxymethyl group on the ethylenediamine bridge yields an amphiphilic conjugate that forms micelles in aqueous solution with a long tumbling time (R). The critical micelle concentration (CMC = 0.34 mM) of the amphiphilic [Gd(EPTPA-C16)(H2O)]2- chelate was determined by variable concentration proton relaxivity measurements. A global analysis of the data obtained in variable temperature and multiple field 17O NMR, and 1H NMRD measurements allowed the determination of parameters governing relaxivity for [Gd(EPTPA-C16)(H2O)]2-; this is the first time that paramagnetic micelles with optimized water exchange are investigated. The water exchange rate was found to be kex298 = 1.7×108 s-1, very similar to that previously reported for the nitrobenzyl derivative [Gd(EPTPA-bz-NO2)(H2O)]2- (kex298 = 1.5×108 s-1). The rotational dynamics of the micelles was analysed using the Lipari-Szabo approach. The micelles formed in aqueous solution show a considerable flexibility, with a local rotational correlation time of the GdIII segments, lO298 = 330 ps, being much shorter than the global rotational correlation time of the supramolecular aggregates, gO298 = 2100 ps. This internal flexibility of the micelles is responsible for the only limited increase of the proton relaxivity observed on micelle formation (r1 = 22.59 mM-1s-1 for the micelles vs. 9.11 mM-1s-1 for the monomer chelate (20 MHz; 25°C)).Fundação para a Ciência e a Tecnologia (FCT) - POCTI/QUI/47005/2002). EU Cost Action D18 "Lanthanide chemistry for diagnosis and therapy". Swiss National Science Foundation. Swiss Federal Office for Education and Science.WileyUniversidade do MinhoTorres, SusanaMartins, J. A. R.André, João P.Geraldes, Carlos F. G. C.Merbach, André E.Tóth, Éva20062006-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/1822/4469eng"Chem. Eur. J." ISSN 0947-6539. 12:7 (2006) 940-948.0947-653910.1002/chem.20050055116224764http://www.wiley-vch.de/publish/en/journals/alphabeticIndex/2111/info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-21T12:32:35Zoai:repositorium.sdum.uminho.pt:1822/4469Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:27:57.996334Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
title |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
spellingShingle |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate Torres, Susana Gadolinium Imaging agents Micelles Steric compression Water exchange MRI CMC Science & Technology |
title_short |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
title_full |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
title_fullStr |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
title_full_unstemmed |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
title_sort |
Supramolecular assembly of an amphiphilic GdIII chelate: tuning the reorientational correlation time and the water exchange rate |
author |
Torres, Susana |
author_facet |
Torres, Susana Martins, J. A. R. André, João P. Geraldes, Carlos F. G. C. Merbach, André E. Tóth, Éva |
author_role |
author |
author2 |
Martins, J. A. R. André, João P. Geraldes, Carlos F. G. C. Merbach, André E. Tóth, Éva |
author2_role |
author author author author author |
dc.contributor.none.fl_str_mv |
Universidade do Minho |
dc.contributor.author.fl_str_mv |
Torres, Susana Martins, J. A. R. André, João P. Geraldes, Carlos F. G. C. Merbach, André E. Tóth, Éva |
dc.subject.por.fl_str_mv |
Gadolinium Imaging agents Micelles Steric compression Water exchange MRI CMC Science & Technology |
topic |
Gadolinium Imaging agents Micelles Steric compression Water exchange MRI CMC Science & Technology |
description |
In this paper we report the synthesis and the characterization of the novel ligand H5EPTPA-C16 ((hydroxymethylhexadecanoyl ester)ethylenepropylenetriaminepentaacetic acid). This ligand was designed to chelate the GdIII ion in a kinetically and thermodynamically stable way while ensuring an increased water exchange rate (kex) on the GdIII complex due to steric compression around the water binding site. The attachment of a palmitic ester unit to the pendant hydroxymethyl group on the ethylenediamine bridge yields an amphiphilic conjugate that forms micelles in aqueous solution with a long tumbling time (R). The critical micelle concentration (CMC = 0.34 mM) of the amphiphilic [Gd(EPTPA-C16)(H2O)]2- chelate was determined by variable concentration proton relaxivity measurements. A global analysis of the data obtained in variable temperature and multiple field 17O NMR, and 1H NMRD measurements allowed the determination of parameters governing relaxivity for [Gd(EPTPA-C16)(H2O)]2-; this is the first time that paramagnetic micelles with optimized water exchange are investigated. The water exchange rate was found to be kex298 = 1.7×108 s-1, very similar to that previously reported for the nitrobenzyl derivative [Gd(EPTPA-bz-NO2)(H2O)]2- (kex298 = 1.5×108 s-1). The rotational dynamics of the micelles was analysed using the Lipari-Szabo approach. The micelles formed in aqueous solution show a considerable flexibility, with a local rotational correlation time of the GdIII segments, lO298 = 330 ps, being much shorter than the global rotational correlation time of the supramolecular aggregates, gO298 = 2100 ps. This internal flexibility of the micelles is responsible for the only limited increase of the proton relaxivity observed on micelle formation (r1 = 22.59 mM-1s-1 for the micelles vs. 9.11 mM-1s-1 for the monomer chelate (20 MHz; 25°C)). |
publishDate |
2006 |
dc.date.none.fl_str_mv |
2006 2006-01-01T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/1822/4469 |
url |
http://hdl.handle.net/1822/4469 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
"Chem. Eur. J." ISSN 0947-6539. 12:7 (2006) 940-948. 0947-6539 10.1002/chem.200500551 16224764 http://www.wiley-vch.de/publish/en/journals/alphabeticIndex/2111/ |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Wiley |
publisher.none.fl_str_mv |
Wiley |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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