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We report a first-in-class responsive, pentafluorosulfanyl (–SF 5 )-tagged 19 F MRI agent capable of reversibly detecting reducing environments via an Fe II/III redox couple. In the Fe III form, the agent displays no 19 F MR signal due to paramagnetic relaxation enhancement-induced signal broadening; however, upon rapid reduction to Fe II with one equivalent of cysteine, the agent displays a robust 19 F signal. Successive oxidation and reduction studies validate the reversibility of the agent. The –SF 5 tag in this agent enables ‘multicolor imaging’ in conjunction with sensors containing alternative fluorinated tags and this was demonstrated via simultaneous monitoring of the 19 F MR signal of this –SF 5 agent and a hypoxia-responsive agent containing a –CF 3 group.
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Design Strategies for Responsive Fluorine‐19 Magnetic Resonance Probes Using Paramagnetic Metal Complexes
Abstract Magnetic resonance imaging (MRI) is a powerful and widely used in vivo imaging technique that enables whole body imaging without ionizing radiation. In clinical practice,1H MRI is employed for imaging anatomical and physiological states via monitoring of protons in water and lipids. In order to monitor biochemical processes at the molecular level, several research groups are exploring responsive MRI agents that alter their signal upon interaction with an analyte or biological environment of interest. Fluorine (19F) MRI agents are promising due to the19F nucleus having similar magnetic resonance (MR) properties to proton and the absence of endogenous19F in living systems, resulting in no background signal. In order to make responsive19F MR agents for molecular imaging and analysis, fluorinated platforms must be developed in which their19F MR signal changes after interacting with a target analyte. A promising strategy is to use paramagnetic metals to modulate the19F MR signal by altering the relaxation rates and/or chemical shift of an appended19F imaging tag. In this concept, we provide an overview of the theoretical principles and molecular design strategies that have been exploited in the design of responsive19F MR agents, with a specific focus on agents based on small molecule paramagnetic metal ion chelates.
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- Award ID(s):
- 1945401
- PAR ID:
- 10401418
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Analysis & Sensing
- Volume:
- 3
- Issue:
- 2
- ISSN:
- 2629-2742
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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