英语专业论文翻译英专业论文翻译.doc

A smart copper(II)-responsive binucleargadolinium(III) complex-based magnetic resonanceimaging contrast agent? Yan-meng Xiao,ab Gui-yan Zhao,ab Xin-xiu Fang,ab Yong-xia Zhao,ab Guan-hua Wang,c Wei Yang*a and Jing-wei Xu*a A novel Gd-DO3A-type bismacrocyclic complex, [Gd2(DO3A)2BMPNA], with a Cu2+-selective binding unitwas synthesized as a potential “smart” copper(II)-responsive magnetic resonance imaging (MRI) contrast agent. The relaxivity of the complex was modulated by the presence or absence of Cu2+; in the absence of Cu2+, the complex exhibited a relatively low relaxivity value (6.40 mM
1 s
1), while the addition of Cu2+ triggered an approximately 76% enhancement in relaxivity (11.28 mM
1 s
1). Moreover, this Cu2+- responsive contrast agent was highly selective in its response to Cu2+ over other biologically-relevant metal ions. The influence of some common biological anions on the Cu2+-responsive contrast agent and the luminescence lifetime of the complex were also studied. The results of the luminescence lifetime measurements indicated that the enhancement in relaxivity was mainly ascribed to the increased number of inner-sphere water molecules binding to the paramagnetic Gd3+ core upon the addition of Cu2+. In addition, the visual change associated with the significantly enhanced relaxivity due to the addition of Cu2+ was observed from T1-weighted phantom images. Introduction Copper(II) ion is a vital metal nutrient for the metabolism of life and plays a critical role in various biological processes.1,2 Its homeostasis is critical for the metabolism and development of living organisms.3,4 On the other hand, the disruption of its homeostasis may lead to a variety of physical diseases and neurological problems such as Alzheimers disease,5 Menkes and Wilsons disease,6 amyotrophic lateral sclerosis,7,8 and prion disease.9,10 Therefore, the assessment and understanding of the distribution of biological copper in living systems by noninvasive imaging is crucial to