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. Author manuscript; available in PMC: 2010 Jul 21.
Published in final edited form as: Acc Chem Res. 2009 Jul 21;42(7):893–903. doi: 10.1021/ar800245h

Figure 5.

Figure 5

(a) Proposed mechanism of a Zn(II)-responsive MR contrast agent. The coordinating acetate arms internally rearrange to bind Zn(II) which opens a coordination site on the Gd(III) center and therefore increases relaxivity. (b) Left: Gd-daa3 Selectivity. T1-weighted MR images of a 1 mM solution of Gd-daa3 in HEPES buffer. (A) HEPES buffer; (B) Gd-daa3; (C) Gd-daa3 with 1 mM ZnCl2; (D) Gd-daa3 with 1 mM MgCl2; (E) Gd-daa3 with 1 mM CaCl2. (b) Right Gd-daa3 Sensitivity. T1-weighted MR images of a 1 mM solution of Gd-daa3 in HEPES buffer with varying zinc concentrations. (A) 0μM Zn; (B) 50 μM Zn; (C) 100 μM Zn; (D) 500 μM Zn; (E) 1 mM Zn.