Synthesis and Evaluation of Nanoglobular Macrocyclic Mn(II) Chelate Conjugates as Non-Gadolinium(III) MRI Contrast Agents

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• 作者：Mingqian Tan ; Zhen Ye ; Eun-Kee Jeong ; Xueming Wu ; Dennis L. Parker ; Zheng-Rong Lu
• 刊名：Bioconjugate Chemistry
• 出版年：2011
• 出版时间：May 18, 2011
• 年：2011
• 卷：22
• 期：5
• 页码：931-937
• 全文大小：908K
• 年卷期：v.22,no.5(May 18, 2011)
• ISSN：1520-4812

文摘

Because of the recent observation of the toxic side effects of Gd(III) based MRI contrast agents in patients with impaired renal function, there is strong interest on developing alternative contrast agents for MRI. In this study, macrocyclic Mn(II) chelates were conjugated to nanoglobular carriers, lysine dendrimers with a silsesquioxane core, to synthesize non-Gd(III) based MRI contrast agents. A generation 3 nanoglobular conjugate of Mn(II)-1,4,7-triaazacyclononane-1,4,7-triacetate-GA amide (G3-NOTA-Mn) was also synthesized and evaluated. The per ion T₁ and T₂ relaxivities of G2, G3, G4 nanoglobular Mn(II)-DOTA monoamide conjugates decreased with increasing generation of the carriers. The T₁ relaxivities of G2, G3, and G4 nanoglobular Mn(II)-DOTA conjugates were 3.3, 2.8, and 2.4 mM^鈥? s^鈥? per Mn(II) chelate at 3 T, respectively. The T₁ relaxivity of G3-NOTA-Mn was 3.80 mM^鈥? s^鈥? per Mn(II) chelate at 3 T. The nanoglobular macrocyclic Mn(II) chelate conjugates showed good in vivo stability and were readily excreted via renal filtration. The conjugates resulted in much less nonspecific liver enhancement than MnCl₂ and were effective for contrast-enhanced tumor imaging in nude mice bearing MDA-MB-231 breast tumor xenografts at a dose of 0.03 mmol Mn/kg. The nanoglobular macrocyclic Mn(II) chelate conjugates are promising nongadolinium based MRI contrast agents.