Gadolinium(III)–fluorescein complex as a dual modal probe for MRI and fluorescence zinc sensing

A bimodal imaging Gd–Zpy probe based on magnetic resonance imaging and fluorescence sensing has been synthesized and characterized. Gd–Zpy features a bright green emission and a turn-on fluorescent response manner with high sensitivity for Zn2+ in aqueous solution and is able to luminescent imaging intracellular Zn2+ levels within living cells. It exhibits a 130% increase of the longitudinal relaxation time and a 115% increase of transverse relaxive time upon addition of Zn2+. The results demonstrated that the incorporating of the fluorescein dye having the efficient chelators within a high-spin Gd3+ system was a powerful approach to achieve dual modal probes for MRI and fluorescence sensing.