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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Polymeric Paracest Agents For Enhancing Mri Contrast Sensitivity, Yunkou Wu, Youfu Zhou, Olivier Quari, Mark Woods, Piyu Zhao, Todd B. Soesbe, Garry Kiefer, A. Dean Sherry
Polymeric Paracest Agents For Enhancing Mri Contrast Sensitivity, Yunkou Wu, Youfu Zhou, Olivier Quari, Mark Woods, Piyu Zhao, Todd B. Soesbe, Garry Kiefer, A. Dean Sherry
Chemistry Faculty Publications and Presentations
Linear polymers of PARACEST agents were prepared by using classical free radical chain polymerization conditions. The Eu3+-polymers exhibited similar intermediate-to-slow water exchange and CEST characteristics as the Eu3+-monomers. This provided an avenue to lower the detection limit of these imaging agents substantially and makes them potentially useful as MRI sensors for molecular imaging.
Towards The Rational Design Of Mri Contrast Agents: Electron Spin Relaxation Is Largely Unaffected By The Coordination Geometry Of Gadolinium(Iii)–Dota-Type Complexes, Alain Borel, Jonathan F. Bean, Robert B. Clarkson, Lothar Helm, Loïck Moriggi, A. Dean Sherry, Mark Woods
Towards The Rational Design Of Mri Contrast Agents: Electron Spin Relaxation Is Largely Unaffected By The Coordination Geometry Of Gadolinium(Iii)–Dota-Type Complexes, Alain Borel, Jonathan F. Bean, Robert B. Clarkson, Lothar Helm, Loïck Moriggi, A. Dean Sherry, Mark Woods
Chemistry Faculty Publications and Presentations
Electron‐spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electron‐spin relaxation is that it is closely related to the ligand‐field parameters of the Gd3+ ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTA‐type ligands could be …
Modulation Of Water Exchange In Europium(Iii) Dota–Tetraamide Complexes Via Electronic Substituent Effects, S. James Ratnakar, Mark Woods, Angelo J.M. Lubag, Zoltan Kovacs, A. Dean Sherry
Modulation Of Water Exchange In Europium(Iii) Dota–Tetraamide Complexes Via Electronic Substituent Effects, S. James Ratnakar, Mark Woods, Angelo J.M. Lubag, Zoltan Kovacs, A. Dean Sherry
Chemistry Faculty Publications and Presentations
The chemical exchange saturation transfer (CEST) efficiency for a series Eu3+-based tetraamide complexes bearing p-substituents on a single coordinating pendant arm is highly sensitive to water exchange rates. The CEST effect increases in the order Me < MeO < F ∼ CO2tBu < CN ≪ H. These results show that CEST contrast can be modulated by changes in electron density at a single ligating atom, and this forms the basis of creating imaging agents that respond to chemical oxidation and reduction.
A Bridge To Coordination Isomer Selection In Lanthanide(Iii) Dota-Tetraamide Complexes, Jeff Vipond, Mark Woods, Piyu Zhao, Gyula Tircsó, Jimin Ren, Simon G. Bott, Doug Ogrin, Garry Kiefer, Zoltan Kovacs, A. Dean Sherry
A Bridge To Coordination Isomer Selection In Lanthanide(Iii) Dota-Tetraamide Complexes, Jeff Vipond, Mark Woods, Piyu Zhao, Gyula Tircsó, Jimin Ren, Simon G. Bott, Doug Ogrin, Garry Kiefer, Zoltan Kovacs, A. Dean Sherry
Chemistry Faculty Publications and Presentations
Interest in macrocyclic lanthanide complexes such as DOTA is driven largely through interest in their use as contrast agents for MRI. The lanthanide tetraamide derivatives of DOTA have shown considerable promise as PARACEST agents, taking advantage of the slow water exchange kinetics of this class of complex. We postulated that water exchange in these tetraamide complexes could be slowed even further by introducing a group to sterically encumber the space above the water coordination site, thereby hindering the departure and approach of water molecules to the complex. The ligand 8O2-bridged-DOTAM was synthesized in a 34% yield from cyclen. …
Europium(Iii) Macrocyclic Complexes With Alcohol Pendant Groups As Chemical Exchange Saturation Transfer Agents, Mark Woods, Donald E. Woessner, Piyu Zhao, Azhar Pasha, Meng-Yin Yang, Ching-Hui Huang, Olga Vasalatiy, Janet R. Morrow, A. Dean Sherry
Europium(Iii) Macrocyclic Complexes With Alcohol Pendant Groups As Chemical Exchange Saturation Transfer Agents, Mark Woods, Donald E. Woessner, Piyu Zhao, Azhar Pasha, Meng-Yin Yang, Ching-Hui Huang, Olga Vasalatiy, Janet R. Morrow, A. Dean Sherry
Chemistry Faculty Publications and Presentations
Paramagnetic lanthanide(III) complexes that contain hyperfine-shifted exchangeable protons offer considerable advantages over diamagnetic molecules as chemical exchange saturation transfer (CEST) agents for MRI. As part of a program to investigate avenues to improve the sensitivity of such agents, the CEST characteristics of europium(III) macrocyclic complexes having appended hydroxyethyl groups were investigated. The CEST spectrum of the asymmetrical complex, EuCNPHC3+, shows five distinct peaks for each magnetically nonequivalent exchangeable proton in the molecule. The CEST spectra of this complex were fitted to NMR Bloch theory to yield exchange rates between each of six exchanging proton pools (five on the …
Towards The Rational Design Of Mri Contrast Agents: A Practical Approach To The Synthesis Of Gadolinium Complexes That Exhibit Optimal Water Exchange, Mark Woods, Mauro Botta, Stefano Avedano, Jing Wang, A. Dean Sherry
Towards The Rational Design Of Mri Contrast Agents: A Practical Approach To The Synthesis Of Gadolinium Complexes That Exhibit Optimal Water Exchange, Mark Woods, Mauro Botta, Stefano Avedano, Jing Wang, A. Dean Sherry
Chemistry Faculty Publications and Presentations
The gadolinium(III) complex of S-SSSS-NO2BnDOTMA exhibits water exchange kinetics that are optimal for use in high relaxivity or targeted contrast agents. However, the synthesis of this ligand is hampered by the steric encumbrance imparted upon the cyclen ring by the nitrobenzyl substituent. A relatively simple modification has been used to enable the synthesis of larger quantities of a bifunctional ligand that retains similar fast water exchange properties. The gadolinium complex of S-SSS-NO2BnDO3MA-1A is shown to retain the rapid water exchange kinetics characteristic of a twisted square antiprismatic (TSAP) …
Toward The Design Of Mr Agents For Imaging Β-Cell Function, Mark Woods, Shanrong Zhang, A. Dean Sherry
Toward The Design Of Mr Agents For Imaging Β-Cell Function, Mark Woods, Shanrong Zhang, A. Dean Sherry
Chemistry Faculty Publications and Presentations
The chemistry of Gd3+-based MRI agents has advanced considerably during the past decade toward agents with higher relaxivity and agents that respond to physiology and / or metabolism. This review describes various approaches that have been taken toward the development of responsive contrast agents and discusses the importance of fast water exchange for advancement of targeted Gd3+-based agents with higher sensitivity. The recent discovery of Eu3+ complexes having extraordinarily slow water exchange has opened a new avenue in contrast agent design based upon the chemical exchange saturation transfer (CEST) mechanism. These new paramagnetic complexes called PARACEST agents offer new possibilities …
Synthesis, Relaxometric And Photophysical Properties Of A New Ph-Responsive Mri Contrast Agent: The Effect Of Other Ligating Groups On Dissociation Of A P-Nitrophenolic Pendant Arm, Mark Woods, Garry Kiefer, Simon G. Bott, Aminta Castillo-Muzquiz, Carrie Eshelbrenner, Lydie Michaudet, Kenneth Mcmillan, Siva D.K. Mudigunda, Doug Ogrin, Gyula Tircso, Shanrong Zhang, Piyu Zhao, A. Dean Sherry
Synthesis, Relaxometric And Photophysical Properties Of A New Ph-Responsive Mri Contrast Agent: The Effect Of Other Ligating Groups On Dissociation Of A P-Nitrophenolic Pendant Arm, Mark Woods, Garry Kiefer, Simon G. Bott, Aminta Castillo-Muzquiz, Carrie Eshelbrenner, Lydie Michaudet, Kenneth Mcmillan, Siva D.K. Mudigunda, Doug Ogrin, Gyula Tircso, Shanrong Zhang, Piyu Zhao, A. Dean Sherry
Chemistry Faculty Publications and Presentations
Two gadolinium(III) chelates, GdNP-DO3A (1-methlyene-(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triAcetate) and GdNP-DO3AM (1-methlyene(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide), containing a single nitrophenolic pendant arm plus either three acetate or three amide pendant arms were synthesized and characterized. The properties of the gadolinium, terbium, and dysprosium complexes of these ligands were examined as a function of pH. The extent and mechanism of the changes in water relaxivity with pH of each gadolinium complex was found to differ substantially for the two complexes. The water relaxivity of Gd(NP-DO3A) increases from 4.1 …