Design and synthesis of a novel magnetic resonance imaging contrast agent for selective sensing of zinc ion

A series of new diethylenetriaminepentaacetic acid (DTPA)-bisamide chelators has been prepared and characterized for application as zinc sensors. We have designed and synthesized (GdLa)(2-), which contains a DTPA-bisamide moiety. The R-1 relaxivity of (GdLa)(2-) solution decreased monotonically on the addition of Zn2+. Moreover, (GdLa)(2-) showed high selectivity for Zn2+ against Ca2+ and Mg2+. We also measured the UV-visible spectra and the coldspray ionization (CSI) MS spectra and concluded that the 1-to-1 Zn2+ complex of (GdLa)(2-) is stable at higher concentrations of Zn2+. These complexes should provide the basis for creating a superior Zn2+-sensitive MRI contrast agent and are excellent candidates for incorporation into sensors designed for selective detection of Zn2+ in biological applications.