Lanthanide Complexes Containing Macrocyclic Ligands for Magnetic Resonance Imaging Contrast Agents PDF Download
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Author: Kam-Cheung Wong
Publisher:
ISBN: 9781374800052
Category :
Languages : en
Pages :
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Author: Kam-Cheung Wong
Publisher:
ISBN: 9781374800052
Category :
Languages : en
Pages :
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Book Description
Author: Kam-cheung Wong (Ph. D.)
Publisher:
ISBN:
Category : Contrast media (Diagnostic imaging)
Languages : en
Pages : 460
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Author: Melissa M. Lewis
Publisher:
ISBN:
Category :
Languages : en
Pages : 410
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Book Description
Magnetic Resonance Imaging (MRI) is a non-invasive technique used in medical imaging with applications in diagnosis, stage determination and monitoring of the progress of disease. Although contrast agents have been used to enhance the image generated by MRI, it still suffers the major shortcoming of low sensitivity. This has led to a thrust to develop contrast agents that improve the sensitivity by relaxation (T1 and T2) as well as by chemical exchange saturation transfer (CEST). To further aid in the development of sensitive MRI contrast agents, the synthesis and evaluation of lanthanide and transition metal complexes was executed. The results are presented herein. Chapter 2 investigated pH dependent reversible binding on CEST effect and relaxivity in macrocyclic complexes possessing three of the same arms and a lone p-nitrophenol arm. Unfortunately, only the Tb3+complex had a small CEST signal. T1 relaxivity of the Gd3+ complex showed high relaxivity at acidic pH and low relaxivity at basic pH. Chapter 3 discussed the rigidification of the DOTAM structure as a means to promote the formation of the SAP isomer for CEST signal generation. These ligands were rigidified by at least one cyclohexyl group and were found to be very selective toward transition metals over lanthanides. However, none of the complexes investigated generated a CEST signal. Chapter 4 attempted to examine the amide CEST signal of DOTAM-tetraanilide complexes containing various para-substituents that would limit T2 exchange and increase amide-based pH measurements. Due to the insolubility of the other complexes, only the p-H and p-OMe complexes were evaluated. The CEST spectrum of the Tm3+-p-OMe complex revealed two amide signals. The absence of a bound water molecule in the Tm3+ agents allowed for higher signal to noise ratios because of reduced T1 and T2 relaxation. Chapter 5 involved a model study that assessed the electronic effects of para-substituents on the amide CEST signal and relaxivity of DO3A-monoanilide complexes. CEST spectra of only the Tm3+complexes could be acquired. The various substituents allowed a CEST effect to be observed at different pH values. The T1 relaxivities of the Dy3+ and Tm3+ complexes were both low, while the Dy3+ complexes had much higher T2 relaxivities as compared to the Tm3+-based ones. Finally, Chapter 6 highlighted the attempt to synthesize para-phosphonate monoanilide analogues of the DOTAM tetraanilide complexes mentioned in Chapter 4, which would be suitable for in vivo studies. It is anticipated that the two amide signals seen in the CEST spectrum of the Tm3+-p-OMe complex would still persist in the modified complex, thus providing a means of a concentration independent ratiometric analysis of the CEST effect. Due to synthetic challenges, the synthesis of these modified complexes is still ongoing.
Author: Carlos F.G.C. Geraldes
Publisher: CRC Press
ISBN: 1040098797
Category : Science
Languages : en
Pages : 427
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Book Description
Since the development of the first clinical MRI contrast agent, Gd(DTPA) (or Magnevist®) in the early 1980s, another three linear and three macrocyclic (eg. Gd(DOTA) (Dotarem®) have been introduced in the clinic and inspired a huge number of researchers worldwide to perform preclinical research to obtain contrast agents for many kinds of clinical applications, which are described in this book. The most current research has been assembled here and can be used by the scientific community to continue increasing the relevance of metal-containing molecules and nanomaterials for MRI-based diagnosis and thus increase the practical use of these systems. Presents the importance of metal-containing molecules and nanomaterials for MRI-based diagnosis and the practical use of these systems. Discusses the structure and dynamics of Ln-based contrast agents as well as computational studies related to these agents. Endorses and stimulates research in the vibrant field of biological inorganic chemistry. Reviews the most current research supporting the relevance of metal-containing molecules and nanomaterials for diagnosis and therapy. The authors are preeminent bioinorganic and medicinal inorganic chemists and review the most current research in this field.
Author: Andre S. Merbach
Publisher: John Wiley & Sons
ISBN: 1118503678
Category : Science
Languages : en
Pages : 514
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Book Description
Magnetic Resonance Imaging (MRI) is one of the most important tools in clinical diagnostics and biomedical research. The number of MRI scanners operating around the world is estimated to be approximately 20,000, and the development of contrast agents, currently used in about a third of the 50 million clinical MRI examinations performed every year, has largely contributed to this significant achievement. This completely revised and extended second edition: Includes new chapters on targeted, responsive, PARACEST and nanoparticle MRI contrast agents. Covers the basic chemistries, MR physics and the most important techniques used by chemists in the characterization of MRI agents from every angle from synthesis to safety considerations. Is written for all of those involved in the development and application of contrast agents in MRI. Presented in colour, it provides readers with true representation and easy interpretation of the images. A word from the Authors: Twelve years after the first edition published, we are convinced that the chemistry of MRI agents has a bright future. By assembling all important information on the design principles and functioning of magnetic resonance imaging probes, this book intends to be a useful tool for both experts and newcomers in the field. We hope that it helps inspire further work in order to create more efficient and specific imaging probes that will allow materializing the dream of seeing even deeper and better inside the living organisms. Reviews of the First Edition: "...attempts, for the first time, to review the whole spectrum of involved chemical disciplines in this technique..."—Journal of the American Chemical Society "...well balanced in its scope and attention to detail...a valuable addition to the library of MR scientists..."—NMR in Biomedicine
Author: Seth Mason Cohen
Publisher:
ISBN:
Category :
Languages : en
Pages : 592
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Author: Pui-Ling Tong
Publisher: Open Dissertation Press
ISBN: 9781374698079
Category :
Languages : en
Pages :
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Book Description
This dissertation, "Lanthanide Complexes for Magnetic Resonance Imaging (MRI) Contrast Agents" by 湯佩玲, Pui-ling, Tong, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b4257621 Subjects: Magnetic resonance imaging Lanthanum compounds Contrast media
Author: Cong Li
Publisher: Open Dissertation Press
ISBN: 9781374708921
Category :
Languages : en
Pages :
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This dissertation, "Lanthanide Complexes for Magnetic Resonance Imaging (MRI) Contrast Agents and Luminescent Sensors" by Cong, Li, 李聰, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled LANTHANIDE COMPLEXES FOR MAGNETIC RESONANCE IMAGING (MRI) CONTRAST AGENTS AND LUMINESCENT SENSORS Submitted by Li Cong for the degree of Doctor of Philosophy at The University of Hong Kong in June 2004 Magnetic resonance imaging (MRI) and bioluminescence imaging are widely used in medical diagnosis. There is a need to develop MRI contrast agents and 3+ 3+ luminescence sensors with higher sensitivity and specificity. Novel Gd and Tb complexes endowed with different functionalities have been synthesized and studied. In this work, a series of general and straightforward methods for the preparation of mono, 1,4 bis and tris N-alkylation of cyclen in high yields and with unprecedented regioselectivity were developed. These protocols are useful in introducing different functional groups to the 1,4,7,10-tetraazacyclododecane (cyclen) in a single step without the use of unnecessary protecting groups. For example, the functionalised 1,4,7-tris-(acetic acid)-1,4,7,10-tetraazacyclododecane (DO3A) derivatives that used to be prepared by multiple steps can now be achieved in two simple steps with attractive features such as high yield, operational convenience and cost economy. 3+ The novel mononuclear Gd polyaminocarboxylates based on cyclen, GdL1- GdL7, were synthesized. Functional groups, such as crown ethers with different ring sizes, β-D-glucopyranose, guanidinium and quinine alkylated diaza-18C6, were introduced into these complexes to achieve target-specificity. The synthesis, structural 1 13 characterization measured by single crystal X-ray analysis, H and C NMR, ESI-MS, HRFAB-MS and elemental analysis, luminescence-lifetime measurements, the relaxometric investigations of the complexes by nuclear magnetic resonance 17 dispersion (NMRD) profiles, variable-temperature O NMR transverse relaxation and pH dependence relaxivity, in vivo MRI studies and in vitro toxicity studies were 3+ discussed. Relaxivities of the four Gd complexes, GdL1, GdL3, GdL5 and GdL6 -1 -1 -1 -1 are in the descending order of GdL1 (9.65 mM s ) > GdL3 (9.36 mM s ) > GdL6 -1 -1 -1 -1 (7.34 mM s ) > GdL5 (3.75 mM s ) measured at 20 MHz and 25C. Compared to -1 -1 the commercially available contrast agents [Gd(DOTA)(H O)] (4.74 mM s ) and -1 -1 [Gd(DO3A)(H O) ] (5.72 mM s ) with two bound water molecules, GdL1, GdL3 2 2 and GdL6 showed much higher relaxivity. The most striking result is the water molecule exchange lifetime of GdL1, which was measured as 55 ns, very close to the optimum value of 20-30 ns in theory. GdL1, GdL3 and GdL6 also demonstrated outstanding performances in the MRI studies based on small animals. The maximal renal and hepatic intensity enhancements (IE) induced by GdL1 were 200% and 105% respectively above the control level, and much higher than those of Gd-DOTA at 123% and 70%. Moreover, GdL1 and GdL3 afforded much longer resident lifetimes in the kidney cortex and liver parenchyma. It is noteworthy that GdL1 showed obvious target-specificity to liver tissue. The maximal hepatic IE induced by GdL1 with low dosage (90%, 0.03 mmol/kg) is even higher than that of Gd-DOTA with three times dosage (70%, 0.1 mmol/kg). Furthermore, an in vitro MTT assay confirmed that the cytotoxicity of GdL1 is quite low even at high concentration (10 mM). The luminescent properties of TbL1, TbL3 and TbL7 were investigated in aqueous solution. TbL
Author: ZhiHang Chen
Publisher:
ISBN: 9781361427316
Category :
Languages : en
Pages :
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Author: Christopher G. Gulgas
Publisher:
ISBN:
Category :
Languages : en
Pages : 133
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Book Description
Novel Eu3-containing macrocyclic complexes were synthesized and studied as anion sensing probe molecules. Several of these macrocycles exhibited unique luminescence responses to hydrogen-bond accepting anions (fluoride, acetate, and dihydrogen phosphate) in DMSO, even in the presence of a chloride ion background. The first series of compounds highlighted a high-yielding synthetic route for highly functional macrocycles that incorporate a Eu3 chelate, aromatic antennae, thiourea groups as anion-binding units, and a variable linker that tunes the size and rigidity of the pocket. These macrocycles exhibited Eu3 luminescence where emission intensity ([lambda]exc = 272 nm, [lambda]em = 614 nm) was correlated to the linker length. Anion-induced changes in emission intensity were dependent on the basicity of the anion, and emission enhancements were observed up to 77% upon titration with fluoride in one case. Through luminescence lifetime studies of the Eu3+ macrocycles and the study of a newly synthesized series of organic model compounds, it was determined that the luminescence response to anions was the result of interaction with the thiourea moieties and no evidence was observed for anion coordination to Eu3+. Additionally, two second-generation macrocycles were synthesized, incorporating an amine unit for stronger binding affinity. One of these macrocycles, featuring a pendant naphthalene antenna, responded to several anions in aqueous solution by means of a luminescence decrease of up to 30%. This general macrocyclic design shows promise for the development of Eu3+-based anion sensors that function in competitive solvents. In continuing work with lanthanide complexes, a new targeted Gd3+-based magnetic resonance imaging contrast agent was designed and synthesized for specific binding to the dopamine receptor protein. A relaxivity of 7.1 mM−1s−1 was measured for this complex at 400 mHz and 310 K.A Eu3+ analogue was also synthesized and structurally characterized. Luminescence lifetime measurements revealed the presence of 2 coordinated water molecules in aqueous solution, consistent with the observed relaxivity of the Gd3+ complex. The synthetic scheme described herein can be extended to the synthesis of a series of targeted complexes for enhanced dopamine receptor binding and imaging studies.
