Metal Ion Sensing Using Ion Chemical Exchange Saturation Transfer 19F Magnetic Resonance Imaging

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• 作者：Amnon Bar-Shir ; Assaf A. Gilad ; Kannie W. Y. Chan ; Guanshu Liu ; Peter C. M. van Zijl ; Jeff W. M. Bulte ; Michael T. McMahon
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：August 21, 2013
• 年：2013
• 卷：135
• 期：33
• 页码：12164-12167
• 全文大小：304K
• 年卷期：v.135,no.33(August 21, 2013)
• ISSN：1520-5126

文摘

Although metal ions are involved in a myriad of biological processes, noninvasive detection of free metal ions in deep tissue remains a formidable challenge. We present an approach for specific sensing of the presence of Ca²⁺ in which the amplification strategy of chemical exchange saturation transfer (CEST) is combined with the broad range of chemical shifts found in ¹⁹F NMR spectroscopy to obtain magnetic resonance images of Ca²⁺. We exploited the chemical shift change (螖蠅) of ¹⁹F upon binding of Ca²⁺ to the 5,5鈥?difluoro derivative of 1,2-bis(o-aminophenoxy)ethane-N,N,N鈥?N鈥?tetraacetic acid (5F-BAPTA) by radiofrequency labeling at the Ca²⁺-bound ¹⁹F frequency and detection of the label transfer to the Ca²⁺-free ¹⁹F frequency. Through the substrate binding kinetics we were able to amplify the signal of Ca²⁺ onto free 5F-BAPTA and thus indirectly detect low Ca²⁺ concentrations with high sensitivity.