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Critical In Vitro Evaluation of Responsive MRI Contrast Agents for Calcium and Zinc
Author(s) -
Mishra Anurag,
Logothetis Nikos K.,
Parker David
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001548
Subject(s) - chemistry , gadolinium , zinc , calcium , dissociation (chemistry) , bicarbonate , metal ions in aqueous solution , metal , in vitro , proton magnetic resonance , nuclear magnetic resonance , mri contrast agent , ion , dissociation constant , biophysics , biochemistry , receptor , physics , organic chemistry , biology
The synthesis of two gadolinium(III) complexes that exhibit an increase in proton relaxivity in the presence of added Ca 2+ or Zn 2+ ions is reported. The complexes increase their hydration state from zero to one following metal‐ion binding, confirmed by spectral measurements on the corresponding Eu III complexes. At a field of 1.4 T and 310 K, modulation of relaxivity of the order of 30–40 % was observed in mouse serum in each case. The dissociation constants for Ca 2+ and Zn 2+ binding were sensitive to the presence of added bicarbonate, and were 450 μ M (Ca 2+ ) and 200 μ M (Zn 2+ ) in serum. Such systems may, therefore, be considered for use as magnetic resonance imaging (MRI) contrast agents to track the restoration of changes in metal‐ion concentration in the cerebrospinal fluid of the brain, following neural stimulation.