Issue 9, 2001

Selective sensing of zinc ions with a novel magnetic resonance imaging contrast agent

Abstract

Light-based microscope imaging techniques using fluorescence sensor molecules suffer from photobleaching and light scattering, but magnetic resonance imaging (MRI) can provide three-dimensional imaging without these problems. Recently, “smart” MRI contrast agents which modulate the access of water to a chelated gadolinium (Gd3+) ion in the presence or absence of a specific trigger have been reported. Zinc (Zn2+) is an essential component of many enzymes, transcription factors and synaptic vesicles in excitatory nerve terminals, so imaging of chelatable Zn2+ is of interest. We have designed and synthesized the Gd3+ DTPA bisamide complex 7a as a Zn2+-sensitive MRI contrast agent. Compound 7a shows a dose-dependent change in the R1 relaxivity in the presence of Zn2+. We investigated this relaxation behavior, and for this purpose we also synthesized the Gd3+ DTPA amide ethyl ester complex 7b. It was shown that binding between 7a and Zn2+ caused a change in the relaxation time. Moreover, 7a had high selectivity for Zn2+ against Ca2+ and Mg2+. Compound 7a may have practical problems for in vivo usage, since the R1 relaxivity is reduced with increased Zn2+ concentration. However, this report demonstrates new approaches to the design and synthesis of Gd3+ complexes with R1 values that change with variation in Zn2+ concentration.

Graphical abstract: Selective sensing of zinc ions with a novel magnetic resonance imaging contrast agent

Supplementary files

Article information

Article type
Paper
Submitted
29 Jan 2001
Accepted
20 Jun 2001
First published
31 Jul 2001

J. Chem. Soc., Perkin Trans. 2, 2001, 1840-1843

Selective sensing of zinc ions with a novel magnetic resonance imaging contrast agent

K. Hanaoka, K. Kikuchi, Y. Urano and T. Nagano, J. Chem. Soc., Perkin Trans. 2, 2001, 1840 DOI: 10.1039/B100994J

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