共查询到20条相似文献,搜索用时 15 毫秒
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Dr. Lorena García-Hevia Dr. Manuel Bañobre-López Dr. Juan Gallo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):431-441
Manganese-based nanostructured contrast agents (CAs) entered the field of medical diagnosis through magnetic resonance imaging (MRI) some years ago. Although some of these Mn-based CAs behave as classic T1 contrast enhancers in the same way as clinical Gd-based molecules do, a new type of Mn nanomaterials have been developed to improve MRI sensitivity and potentially gather new functional information from tissues by using traditional T1 contrast enhanced MRI. These nanomaterials have been designed to respond to biological environments, mainly to pH and redox potential variations. In many cases, the differences in signal generation in these responsive Mn-based nanostructures come from intrinsic changes in the magnetic properties of Mn cations depending on their oxidation state. In other cases, no changes in the nature of Mn take place, but rather the nanomaterial as a whole responds to the change in the environment through different mechanisms, including changes in integrity and hydration state. This review focusses on the chemistry and MR performance of these responsive Mn-based nanomaterials. 相似文献
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A Class of FeIII Macrocyclic Complexes with Alcohol Donor Groups as Effective T1 MRI Contrast Agents
Eric M. Snyder Didar Asik Samira M. Abozeid Ariel Burgio Gage Bateman Steven G. Turowski Joseph A. Spernyak Janet R. Morrow 《Angewandte Chemie (International ed. in English)》2020,59(6):2414-2419
Early studies suggested that FeIII complexes cannot compete with GdIII complexes as T1 MRI contrast agents. Now it is shown that one member of a class of high‐spin macrocyclic FeIII complexes produces more intense contrast in mice kidneys and liver at 30 minutes post‐injection than does a commercially used GdIII agent and also produces similar T1 relaxivity in serum phantoms at 4.7 T and 37 °C. Comparison of four different FeIII macrocyclic complexes elucidates the factors that contribute to relaxivity in vivo including solution speciation. Variable‐temperature 17O NMR studies suggest that none of the complexes has a single, integral inner‐sphere water that exchanges rapidly on the NMR timescale. MRI studies in mice show large in vivo differences of three of the FeIII complexes that correspond, in part, to their r1 relaxivity in phantoms. Changes in overall charge of the complex modulate contrast enhancement, especially of the kidneys. 相似文献
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Sanhita Sinharay Gabriela Fernández‐Cuervo Jasmine P. Acfalle Mark D. Pagel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6491-6495
A chemical exchange saturation transfer (CEST) MRI contrast agent has been developed that detects sulfatase enzyme activity. The agent produces a CEST signal at δ=5.0 ppm before enzyme activity, and a second CEST signal appears at δ=9.0 ppm after the enzyme cleaves a sulfate group from the agent. The comparison of the two signals improved detection of sulfatase activity. 相似文献
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Priv.‐Doz. Dr. Goran Angelovski 《Angewandte Chemie (International ed. in English)》2016,55(25):7038-7046
Bioresponsive MRI contrast agents hold great promise for monitoring major physiological and pathological processes in a non‐invasive manner. They are capable of altering the acquired MRI signal as a consequence of changes in their microenvironment, thus allowing real‐time functional reporting in living organisms. Importantly, chemistry offers diverse solutions for the design of agents which respond to a great number of specific targets. However, the path to the successful utilization of these biomarkers in the desired functional MRI studies involves careful consideration of multiple scientific, technical, and practical issues across various research disciplines. This Minireview highlights the critical steps for planning and executing such multidisciplinary projects with an aim to substantially improve our knowledge of essential biological processes. 相似文献
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Lorenzo Tei Dr. Alessandro Barge Dr. Simonetta Geninatti Crich Dr. Roberto Pagliarin Dr. Viviana Negri Dr. Daniela Ramella Dr. Giancarlo Cravotto Prof. Silvio Aime Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(27):8080-8087
To design efficient targeting strategies in magnetic resonance (MR) molecular imaging applications, the formation of supramolecular adducts between (strept)avidin ((S)Av) and tribiotinylated Gd‐DOTA‐monoamide complexes (DOTA=1,4,7,10‐tetraazacyclododecane‐N,N′,N′′,N′′′‐tetraacetic acid) was explored. Two compounds based on the trivalent core of tris(2‐aminoethyl)amine each containing three biotin molecules and one ( L1 ) or three ( L2 ) DOTA‐monoamide (DOTAMA) ligands were synthesized. In these tribiotinylated derivatives the biotins are spaced far enough apart to allow the formation of the supramolecular adduct with the protein and to host the chelating units in between the (S)Av layers. Size exclusion HPLC analyses indicated complete formation of very high molecular weight polymers (>2 MDa) with (S)Av in solution. A 1H NMR spectroscopy relaxometric study on the obtained polymeric adducts showed a marked increase of the relaxivity at 35–40 MHz as a consequence of the lengthening of the tumbling time due to the formation of Gd‐chelates/(S)Av polymers. The most efficient Gd3 L2 /(S)Av polymeric system was used for a test in cell cultures. The target is represented by a neural cell adhesion molecule (NCAM), which is overexpressed in Kaposi’s sarcoma cells and tumor endothelial cells (TEC) and that is efficiently recognized by a biotinylated tetrameric peptide (C3d‐Bio). In vitro experiments showed that only cells incubated with both C3d‐Bio and Gd3 L2 /SAv polymer were hyperintense with respect to the control. Relaxation rates of cell pellets incubated with Gd3 L2 /SAv alone were not significantly different from the untreated cells demonstrating the absence of a specific binding. 相似文献
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Dr. Martín Regueiro‐Figueroa Dr. Gabriele A. Rolla Dr. David Esteban‐Gómez Dr. Andrés de Blas Dr. Teresa Rodríguez‐Blas Prof. Mauro Botta Dr. Carlos Platas‐Iglesias 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17300-17305
Stable Mn2+ mono‐ and binuclear complexes containing pentadentate 6,6′‐((methylazanediyl)bis(methylene))dipicolinic acid coordinating units give remarkably high relaxivities due to the presence of two inner‐sphere water molecules. The mononuclear derivative binds human serum albumin (HSA) with an association constant of 3372 M ?1, which results in the replacement of the coordinated water molecules by donor atoms of protein residues. The dinuclear analogue also binds HSA while leaving one of the Mn2+ centres exposed to the solvent with two coordinated water molecules. Thus, this complex shows remarkably high relaxivities upon protein binding (39.0 mM ?1 s?1 per Mn, at 20 MHz and 37 °C). 相似文献
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Zuzana Kotková Dr. Jan Kotek Dr. Daniel Jirák Dr. Pavla Jendelová Dr. Vít Herynek Dr. Zuzana Berková Dr. Petr Hermann Dr. Ivan Lukeš Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10094-10102
A novel bimodal fluorescence/MRI probe based on a cyclodextrin scaffold has been synthesized and characterized. The final agent employs the fluorescein (F) functionality as a fluorescence marker and the GdIII complex of a macrocyclic DOTA‐based ligand (GdL) having one aminobenzyl‐phosphinic acid pendant arm as an MRI probe, and has a statistical composition of (GdL)6.9‐F0.1‐β‐CD. Slow rotational dynamics (governed by a very rigid cyclodextrin scaffold) combined with fast water exchange (ensured by the chosen macrocyclic ligand) resulted in a high relaxivity of ~22 s?1 mM ?1 per GdIII or ~150 s?1 mM ?1 per molecule of the final conjugate (20 MHz, 25 °C). In vitro labelling of pancreatic islets (PIs) and rat mesenchymal stem cells has been successfully performed. The agent is not cytotoxic and is easily internalized into cells. The labelled cells can be visualized by MRI, as proved by the detection of individual labelled PIs. A fluorescence study performed on mesenchymal stem cells showed that the agent stays in the intracellular space for a long time. 相似文献
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以两种夹心型锰杂多配合物K10[Mn4(PW9O34)2]·22H2O和Na16[Mn4(H2O)2(P2W15O56)2]·53H2O作为研究对象, 采用元素分析和红外光谱对其结构进行了表征, 测试其在水中、牛血清白蛋白及运铁蛋白溶液中的弛豫效率, 并进行了大鼠活体成像实验. 结果表明, 这两种锰杂多配合物的弛豫效率高于或接近于目前临床常用的造影剂Gd-DTPA, 对肝脏和肾脏MRI信号具有良好的增强效果, 是比较好的潜在磁共振成像造影剂候选化合物. 相似文献
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Tuning Phenols with Intra‐Molecular Bond Shifted HYdrogens (IM‐SHY) as diaCEST MRI Contrast Agents 下载免费PDF全文
Xing Yang Nirbhay N. Yadav Xiaolei Song Prof. Sangeeta Ray Banerjee Hannah Edelman Il Minn Prof. Peter C. M. van Zijl Prof. Martin G. Pomper Prof. Michael T. McMahon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(48):15824-15832
The optimal exchange properties for chemical exchange saturation transfer (CEST) contrast agents on 3 T clinical scanners were characterized using continuous wave saturation transfer, and it was demonstrated that the exchangeable protons in phenols can be tuned to reach these criteria through proper ring substitution. Systematic modification allows the chemical shift of the exchangeable protons to be positioned between 4.8 to 12 ppm from water and enables adjustment of the proton exchange rate to maximize CEST contrast at these shifts. In particular, 44 hydrogen‐bonded phenols are investigated for their potential as CEST MRI contrast agents and the stereoelectronic effects on their CEST properties are summarized. Furthermore, a pair of compounds, 2,5‐dihydroxyterephthalic acid and 4,6‐dihydroxyisophthalic acid, were identified which produce the highest sensitivity through incorporating two exchangeable protons per ring. 相似文献
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Preparation of Highly Efficient MRI Contrast Agents through Complexation of Cationic GdIII‐Containing Metallosurfactant with Biocompatible Polyelectrolytes 下载免费PDF全文
Yingying Chen Qin Zhu Xinghui Cui Weijun Tang Heng Yang Prof. Yuan Yuan Prof. Aiguo Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12477-12482
Novel contrast agents were developed through assembling of GdIII‐containing metallosurfactant (MS) with biocompatible polyelectrolytes sodium hyaluronate (HA), heparinsodium (HS) and dextran sulfate sodium (DSS). The formed polyelectrolyte–surfactant complexes showed different structural patterns as the charge ratio increased, including spherical aggregates, rod‐like aggregates and network patterns in monovalent HA system, while spherical structures emerged in multivalent HS and DSS systems. Energy dispersive spectroscopy analysis and scanning electron microscopy mapping showed the presence of GdIII in these complexes. Inductively coupled plasma atomic emission spectrometry was further used to quantify the contents of GdIII in the assemblies. T1 magnetic resonance imaging showed that these GdIII‐loaded complexes exhibited relaxivity of up to 63.81 mM ?1 s?1, much higher than that of Ominiscan (4.64 mM ?1 s?1). The cytotoxicity test in vitro demonstrated the excellent biocompatibility of these complexes, which is essential for clinical application. 相似文献
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A pH‐Responsive MRI Agent that Can Be Activated Beyond the Tissue Magnetization Transfer Window 下载免费PDF全文
Xiaojing Wang Dr. Yunkou Wu Dr. Todd C. Soesbe Dr. Jing Yu Dr. Piyu Zhao Dr. Garry E. Kiefer Prof. A. Dean Sherry 《Angewandte Chemie (International ed. in English)》2015,54(30):8662-8664
A terbium‐based complex that displays a water exchange CEST resonance well outside the normal magnetization transfer (MT) frequency range of tissues provides a direct readout of pH values by MRI. Deprotonation of the phenolic proton in this complex results in a frequency shift of 56 ppm in a bound water molecule exchange peak between pH 5 and 8. This allows direct imaging of pH without prior knowledge of the agent concentration and with essentially no interference from the tissue MT signal. 相似文献