The pH sensitivity of −NH exchange in LnDOTA-tetraamide complexes varies with amide substituent
Identifieur interne : 000217 ( Pmc/Corpus ); précédent : 000216; suivant : 000218The pH sensitivity of −NH exchange in LnDOTA-tetraamide complexes varies with amide substituent
Auteurs : Ana Christina L. Opina ; Yunkou Wu ; Piyu Zhao ; Garry Kiefer ; A. Dean SherrySource :
- Contrast media & molecular imaging [ 1555-4309 ] ; 2011.
Abstract
The amide proton exchange rates in various lanthanide(III) DOTA-tetraamide complexes were investigated by CEST as a function of variable chemical structures and charges on the amide substituents. Comparisons were made between YbDOTA-(gly)4− (Yb-1), YbDOTA-(NHCH2PO3)45− (Yb-2), and YbDOTA-(NHCH2PO3Et2)43+ (Yb-3). The general shapes of the CEST versus pH profiles were similar for the three complexes but they showed maximum CEST intensities at different pH values, pH 8.3, 8.8 and 6.9 for Yb-1, Yb-2 and Yb-3, respectively. This indicates that a more negatively charged substituent on the amide helps stabilize the partial positive charge on the amide nitrogen and consequently more base is required to catalyze proton exchange. The chemical shifts of the −NH protons in Yb-1 and Yb-2 were similar (−17 ppm) while the −NH proton in Yb-3 was at −13 ppm. This shows that crystal field produced by the amide oxygen donor atoms in Yb-3 is substantially weaker than that in the other two complexes. In an effort to expand the useful range of pH values that might be measured using these complexes as CEST agents, the shapes of the CEST versus pH curves were also determined for two thulium(III) complexes with much larger hyperfine shifted −NH proton resonances. The ratio of CEST from −NH exchange in Tm-1 compared to CEST from −NH exchange in Tm-3 was found to be linear over an extended pH range, from 6.3 to 7.4. This demonstrates a potential advantage of using mixtures of lanthanide(III) DOTA-tetraamides for mapping tissue pH by use of ratiometric CEST imaging.
Url:
DOI: 10.1002/cmmi.445
PubMed: 22144023
PubMed Central: 3233223
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PMC:3233223Le document en format XML
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<author><name sortKey="Opina, Ana Christina L" sort="Opina, Ana Christina L" uniqKey="Opina A" first="Ana Christina L." last="Opina">Ana Christina L. Opina</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Wu, Yunkou" sort="Wu, Yunkou" uniqKey="Wu Y" first="Yunkou" last="Wu">Yunkou Wu</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
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<author><name sortKey="Zhao, Piyu" sort="Zhao, Piyu" uniqKey="Zhao P" first="Piyu" last="Zhao">Piyu Zhao</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Kiefer, Garry" sort="Kiefer, Garry" uniqKey="Kiefer G" first="Garry" last="Kiefer">Garry Kiefer</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Sherry, A Dean" sort="Sherry, A Dean" uniqKey="Sherry A" first="A. Dean" last="Sherry">A. Dean Sherry</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
<affiliation><nlm:aff id="A2">Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-8568, UNITED STATES</nlm:aff>
</affiliation>
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<sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">The pH sensitivity of −NH exchange in LnDOTA-tetraamide complexes varies with amide substituent</title>
<author><name sortKey="Opina, Ana Christina L" sort="Opina, Ana Christina L" uniqKey="Opina A" first="Ana Christina L." last="Opina">Ana Christina L. Opina</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Wu, Yunkou" sort="Wu, Yunkou" uniqKey="Wu Y" first="Yunkou" last="Wu">Yunkou Wu</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Zhao, Piyu" sort="Zhao, Piyu" uniqKey="Zhao P" first="Piyu" last="Zhao">Piyu Zhao</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Kiefer, Garry" sort="Kiefer, Garry" uniqKey="Kiefer G" first="Garry" last="Kiefer">Garry Kiefer</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Sherry, A Dean" sort="Sherry, A Dean" uniqKey="Sherry A" first="A. Dean" last="Sherry">A. Dean Sherry</name>
<affiliation><nlm:aff id="A1">Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</nlm:aff>
</affiliation>
<affiliation><nlm:aff id="A2">Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-8568, UNITED STATES</nlm:aff>
</affiliation>
</author>
</analytic>
<series><title level="j">Contrast media & molecular imaging</title>
<idno type="ISSN">1555-4309</idno>
<idno type="eISSN">1555-4317</idno>
<imprint><date when="2011">2011</date>
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<front><div type="abstract" xml:lang="en"><p id="P1">The amide proton exchange rates in various lanthanide(III) DOTA-tetraamide complexes were investigated by CEST as a function of variable chemical structures and charges on the amide substituents. Comparisons were made between YbDOTA-(gly)<sub>4</sub>
<sup>−</sup>
(Yb-1), YbDOTA-(NHCH<sub>2</sub>
PO<sub>3</sub>
)<sub>4</sub>
<sup>5−</sup>
(Yb-2), and YbDOTA-(NHCH<sub>2</sub>
PO<sub>3</sub>
Et<sub>2</sub>
)<sub>4</sub>
<sup>3+</sup>
(Yb-3). The general shapes of the CEST versus pH profiles were similar for the three complexes but they showed maximum CEST intensities at different pH values, pH 8.3, 8.8 and 6.9 for Yb-1, Yb-2 and Yb-3, respectively. This indicates that a more negatively charged substituent on the amide helps stabilize the partial positive charge on the amide nitrogen and consequently more base is required to catalyze proton exchange. The chemical shifts of the −NH protons in Yb-1 and Yb-2 were similar (−17 ppm) while the −NH proton in Yb-3 was at −13 ppm. This shows that crystal field produced by the amide oxygen donor atoms in Yb-3 is substantially weaker than that in the other two complexes. In an effort to expand the useful range of pH values that might be measured using these complexes as CEST agents, the shapes of the CEST versus pH curves were also determined for two thulium(III) complexes with much larger hyperfine shifted −NH proton resonances. The ratio of CEST from −NH exchange in Tm-1 compared to CEST from −NH exchange in Tm-3 was found to be linear over an extended pH range, from 6.3 to 7.4. This demonstrates a potential advantage of using mixtures of lanthanide(III) DOTA-tetraamides for mapping tissue pH by use of ratiometric CEST imaging.</p>
</div>
</front>
</TEI>
<pmc article-type="research-article" xml:lang="EN"><pmc-comment>The publisher of this article does not allow downloading of the full text in XML form.</pmc-comment>
<pmc-dir>properties manuscript</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-journal-id">101286760</journal-id>
<journal-id journal-id-type="pubmed-jr-id">33141</journal-id>
<journal-id journal-id-type="nlm-ta">Contrast Media Mol Imaging</journal-id>
<journal-title>Contrast media & molecular imaging</journal-title>
<issn pub-type="ppub">1555-4309</issn>
<issn pub-type="epub">1555-4317</issn>
</journal-meta>
<article-meta><article-id pub-id-type="pmid">22144023</article-id>
<article-id pub-id-type="pmc">3233223</article-id>
<article-id pub-id-type="doi">10.1002/cmmi.445</article-id>
<article-id pub-id-type="manuscript">NIHMS279651</article-id>
<article-categories><subj-group subj-group-type="heading"><subject>Article</subject>
</subj-group>
</article-categories>
<title-group><article-title>The pH sensitivity of −NH exchange in LnDOTA-tetraamide complexes varies with amide substituent</article-title>
</title-group>
<contrib-group><contrib contrib-type="author"><name><surname>Opina</surname>
<given-names>Ana Christina L.</given-names>
</name>
<xref ref-type="aff" rid="A1">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Wu</surname>
<given-names>Yunkou</given-names>
</name>
<xref ref-type="aff" rid="A1">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Zhao</surname>
<given-names>Piyu</given-names>
</name>
<xref ref-type="aff" rid="A1">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Kiefer</surname>
<given-names>Garry</given-names>
</name>
<xref ref-type="aff" rid="A1">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Sherry</surname>
<given-names>A. Dean</given-names>
</name>
<xref ref-type="corresp" rid="CR1">*</xref>
<xref ref-type="aff" rid="A1">†</xref>
<xref ref-type="aff" rid="A2">§</xref>
</contrib>
</contrib-group>
<aff id="A1"><label>†</label>
Department of Chemistry, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75083-0688, UNITED STATES</aff>
<aff id="A2"><label>§</label>
Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-8568, UNITED STATES</aff>
<author-notes><corresp id="CR1"><label>*</label>
To whom correspondence should be addressed. <email>sherry@utdallas.edu</email>
; <email>dean.sherry@utsouthwestern.edu</email>
</corresp>
</author-notes>
<pub-date pub-type="nihms-submitted"><day>14</day>
<month>3</month>
<year>2011</year>
</pub-date>
<pub-date pub-type="ppub"><month>11</month>
<year>2011</year>
</pub-date>
<pub-date pub-type="pmc-release"><day>1</day>
<month>11</month>
<year>2012</year>
</pub-date>
<volume>6</volume>
<issue>6</issue>
<fpage>459</fpage>
<lpage>464</lpage>
<abstract><p id="P1">The amide proton exchange rates in various lanthanide(III) DOTA-tetraamide complexes were investigated by CEST as a function of variable chemical structures and charges on the amide substituents. Comparisons were made between YbDOTA-(gly)<sub>4</sub>
<sup>−</sup>
(Yb-1), YbDOTA-(NHCH<sub>2</sub>
PO<sub>3</sub>
)<sub>4</sub>
<sup>5−</sup>
(Yb-2), and YbDOTA-(NHCH<sub>2</sub>
PO<sub>3</sub>
Et<sub>2</sub>
)<sub>4</sub>
<sup>3+</sup>
(Yb-3). The general shapes of the CEST versus pH profiles were similar for the three complexes but they showed maximum CEST intensities at different pH values, pH 8.3, 8.8 and 6.9 for Yb-1, Yb-2 and Yb-3, respectively. This indicates that a more negatively charged substituent on the amide helps stabilize the partial positive charge on the amide nitrogen and consequently more base is required to catalyze proton exchange. The chemical shifts of the −NH protons in Yb-1 and Yb-2 were similar (−17 ppm) while the −NH proton in Yb-3 was at −13 ppm. This shows that crystal field produced by the amide oxygen donor atoms in Yb-3 is substantially weaker than that in the other two complexes. In an effort to expand the useful range of pH values that might be measured using these complexes as CEST agents, the shapes of the CEST versus pH curves were also determined for two thulium(III) complexes with much larger hyperfine shifted −NH proton resonances. The ratio of CEST from −NH exchange in Tm-1 compared to CEST from −NH exchange in Tm-3 was found to be linear over an extended pH range, from 6.3 to 7.4. This demonstrates a potential advantage of using mixtures of lanthanide(III) DOTA-tetraamides for mapping tissue pH by use of ratiometric CEST imaging.</p>
</abstract>
<kwd-group><kwd>MRI</kwd>
<kwd>contrast agents</kwd>
<kwd>pH-responsive agents</kwd>
<kwd>paramagnetic agents</kwd>
<kwd>Chemical Exchange Saturation Transfer (CEST) agents</kwd>
<kwd>amide proton exchange</kwd>
<kwd>ratiometric analysis</kwd>
</kwd-group>
<contract-num rid="EB1">R01 EB004582-04
||EB</contract-num>
<contract-num rid="CA1">R01 CA115531-05
||CA</contract-num>
<contract-num rid="RR1">P41 RR002584-22
||RR</contract-num>
<contract-sponsor id="EB1">National Institute of Biomedical Imaging and Bioengineering : NIBIB</contract-sponsor>
<contract-sponsor id="CA1">National Cancer Institute : NCI</contract-sponsor>
<contract-sponsor id="RR1">National Center for Research Resources : NCRR</contract-sponsor>
</article-meta>
</front>
</pmc>
</record>
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