@article{cf5f625332474bd0a5539d1de86d3341,
title = "A Frequency-Selective pH-Responsive paraCEST Agent",
abstract = "Paramagnetic chemical exchange saturation transfer (paraCEST) agents are well-suited for imaging tissue pH because the basis of CEST, chemical exchange, is inherently sensitive to pH. Several previous pH-sensitive paraCEST agents were based on an exchanging Ln3+-bound water molecule as the CEST antenna but this design often added additional line-broadening to the bulk water signal due to T2 exchange. We report herein a pH-sensitive paraCEST agent that lacks an inner-sphere water molecule but contains one Ln-bound −OH group for CEST activation. The Yb3+ complex, Yb(1), displayed a single, highly shifted CEST peak originating from the exchangeable Yb-OH proton, the frequency of which changed over the biologically relevant pH range. CEST images of phantoms ranging in pH from 6 to 8 demonstrate the potential of this agent for imaging pH. Initial rodent imaging studies showed that Gd(1) remains in the vascular system much longer than anticipated but is cleared slowly via renal filtration.",
keywords = "contrast agents, imaging agents, lanthanide complexes, pH sensing, paraCEST",
author = "Ratnakar, {S. James} and Sara Chirayil and Funk, {Alexander M.} and Shanrong Zhang and Queir{\'o}, {Jo{\~a}o F.} and Geraldes, {Carlos F.G.C.} and Zoltan Kovacs and Sherry, {A. Dean}",
note = "Funding Information: ADS acknowledges partial financial support for this work from the National Institutes of Health (CA-115531 and EB-02584) and the Robert A. Welch Foundation (AT-584). JFQ acknowledges support by FCT-Portugal (Portuguese Foundation for Science and Technology) and FEDER (European Regional Development Fund -PT2020) through the Centre for Mathematics (UID/MAT/00324/2019). CFGCG acknowledges the Coimbra Chemistry Centre Center (UID/QUI/00313/2019 and POCI-01-0145- FEDER-027996) of the University of Coimbra, and a Fulbright visiting scholarship. Funding Information: ADS acknowledges partial financial support for this work from the National Institutes of Health (CA‐115531 and EB‐02584) and the Robert A. Welch Foundation (AT‐584). JFQ acknowledges support by FCT‐Portugal (Portuguese Foundation for Science and Technology) and FEDER (European Regional Development Fund ‐PT2020) through the Centre for Mathematics (UID/MAT/00324/2019). CFGCG acknowledges the Coimbra Chemistry Centre Center (UID/QUI/00313/2019 and POCI‐01‐0145‐ FEDER‐027996) of the University of Coimbra, and a Fulbright visiting scholarship. Publisher Copyright: {\textcopyright} 2020 Wiley-VCH GmbH",
year = "2020",
month = nov,
day = "23",
doi = "10.1002/anie.202008888",
language = "English (US)",
volume = "59",
pages = "21671--21676",
journal = "Angewandte Chemie - International Edition",
issn = "1433-7851",
publisher = "John Wiley and Sons Ltd",
number = "48",
}