Gd3+-Based Magnetic Resonance Imaging Contrast Agent Responsive to Zn2+

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• 作者：Mart铆n Regueiro-Figueroa ; Serhat G眉nd眉z ; V茅ronique Patinec ; Nikos K. Logothetis ; David Esteban-G贸mez ; Rapha毛l Tripier ; Goran Angelovski ; Carlos Platas-Iglesias
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 2, 2015
• 年：2015
• 卷：54
• 期：21
• 页码：10342-10350
• 全文大小：554K
• ISSN：1520-510X

文摘

We report the heteroditopic ligand H₅L, which contains a DO3A unit for Gd³⁺ complexation connected to an NO2A moiety through a N-propylacetamide linker. The synthesis of the ligand followed a convergent route that involved the preparation of 1,4-bis(tert-butoxycarbonylmethyl)-1,4,7-triazacyclononane following the orthoamide strategy. The luminescence lifetimes of the Tb(⁵D₄) excited state measured for the TbL complex point to the absence of coordinated water molecules. Density functional theory calculations and ¹H NMR studies indicate that the EuL complex presents a square antiprismatic coordination in aqueous solution, where eight coordination is provided by the seven donor atoms of the DO3A unit and the amide oxygen atom of the N-propylacetamide linker. Addition of Zn²⁺ to aqueous solutions of the TbL complex provokes a decrease of the emission intensity as the emission lifetime becomes shorter, which is a consequence of the coordination of a water molecule to the Tb³⁺ ion upon Zn²⁺ binding to the NO2A moiety. The relaxivity of the GdL complex recorded at 7 T (25 掳C) increases by almost 150% in the presence of 1 equiv of Zn²⁺, while Ca²⁺ and Mg²⁺ induced very small relaxivity changes. In vitro magnetic resonance imaging experiments confirmed the ability of GdL to provide response to the presence of Zn²⁺.