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Zn 2+ ‐Responsive Bimodal Magnetic Resonance Imaging and Fluorescence Imaging Agents and Their Interaction with Human Serum Albumin
Author(s) -
Xu YingQi,
Luo Jian,
Chen ZhongNing
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402197
Subject(s) - gadolinium , chemistry , human serum albumin , fluorescence , crystallography , denticity , nephrogenic systemic fibrosis , nuclear magnetic resonance , crystal structure , biochemistry , physics , organic chemistry , quantum mechanics
The gadolinium(III) complexes Gd L1 and Gd L2 were designed as Zn 2+ ‐responsive bimodal magnetic resonance imaging (MRI) and fluorescence imaging probes. Upon binding to Zn 2+ ions, Gd L1 exhibits a bidentate or tridentate mode to form heterodinuclear Gd L1 Zn or heterotrinuclear (Gd L1 ) 2 Zn, whereas Gd L2 binds to the Zn 2+ ion only in a bidentate mode to form (Gd L2 ) 2 Zn. The gadolinium(III) complexes derived from both H 3 L1 and H 3 L2 exhibit remarkable interactions with human serum albumin (HSA) at both site I and site II, which result in significant enhancements of the relaxivity and remarkable improvements of T 1 ‐weighted imaging contrast. In the presence of HSA, both the relaxivity ( r 1 ) and fluorescence exhibit 300 % enhancement with a clear blueshift of the fluorescence for Gd L1 Zn, which is ascribed to direct binding to HSA through the formation of a Zn–HSA coordination bond. In contrast, the presence of HSA induces smaller relaxivity increases for Gd L1 (155 %), (Gd L1 ) 2 Zn (183 %), Gd L2 (192 %), and (Gd L2 ) 2 Zn (181 %); these increases are ascribed to weaker hydrophobic interactions or stereospecificity with HSA. The contrast of T 1 ‐weighted phantom MR images of these gadolinium(III) complexes in human serum (HS) is much improved relative to that in 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid (HEPES) buffer solutions.