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1、磁共振成像磁共振成像现在学习的是第1页，共19页The Paper现在学习的是第2页，共19页OutlineConclusion3Introduction1Experimental Section 2现在学习的是第3页，共19页1、IntroductionMolecular imaging It seems to take photos of molecular,display the morphological structure of our target.In other words,characterization and measurement of the process of l
2、iving animals,human biology and model system in the cellular and molecular level using the imaging detector in vitro.Features of molecular imaging Non-invasive imaging technique Dynamic acquisition Reflect full-scale现在学习的是第4页，共19页Some main imaging techniques Positron emission tomography(PET)Single p
3、hoton emission computed tomography(SPECT)Magnetic resonance imaging(MRI)Ultrasonic imaging Optical imaging(Bioluminescence,Fluorescence)现在学习的是第5页，共19页MRIMagnetic resonance imaging(MRI)is one of the most important techniques in medical imaging.It is noninvasive,avoids problems occurring in other imag
4、ing techniques such as scattering(optical imaging)or high-energy radiation(computed tomography(CT)or X-ray),and enables the production of 3D images of various tissues.现在学习的是第6页，共19页The challenge is to prepare complexes that do not release the toxic metal ion in vivo and yet are efficient contrast ag
5、ents.现在学习的是第7页，共19页2、Experimental SectionThe contrast is generated by differences in either the proton density between tissues and/or differences in T1 or T2 relaxation times.A noncovalent approach is to prepare amphiphilic compounds that form aggregates.Targeted contrast agents usually have higher
6、relaxivities when interacting with the target due to the restriction of the rotational motion upon binding.现在学习的是第8页，共19页In MRI an ongoing trend is to apply higher magnetic field strengths(1.5 T).This can be achieved by optimizing the average water residence lifetime tM to even shorter values than t
7、hat predicted of 2040 ns for high molecular weight agents.现在学习的是第9页，共19页One of approaches to find systems with optimal R is to use the rather rigid calix4arene core as a synthetic platform.Calixarenes generally enable the introduction of at least two different functions.现在学习的是第10页，共19页Aggregation现在学
8、习的是第11页，共19页Variable-temperature 17O NMR measurementsWithin the experimental error,the hyperfine coupling constant is identical to commonly observed values for oxygen atoms directly coordinated to Gd.现在学习的是第12页，共19页Nuclear magnetic relaxation dispersion NMRD is a powerful technique for characterizin
9、g MRI contrast agents.NMRD profiles show the relaxivity of the monomer to be almost independent of the magnetic field strength up to 60 MHz.现在学习的是第13页，共19页Interaction with HASIt has been shown previously that calix4arenes can interact with the hydrophobic transport protein HSA,due to their apolar st
10、ructure.The affinity of hydrophobic compounds with HSA is an ongoing topic in modern MRI research since both relaxivity and pharmacokinetics can be controlled by noncovalent binding of contrast agents to HSA.现在学习的是第14页，共19页To compare our results with literature data on calixarene-based Gd complexes
11、interacting with HSA,we followed the procedure described for these systems and assumed that there is,effectively,only a single binding site in HAS.We also performed NMRD measurements at 37 on a solution containing 4%HSA(0.6mm)and 1(0.47mm).现在学习的是第15页，共19页The electronic parameters are in the same ran
12、ge as thoseof the micellar aggregates and of the monomer.现在学习的是第16页，共19页3、ConclusionThe novel noncharged self-aggregating calix4arene-based MRI contrast agent described here exhibits good relaxivities over a broad range of Lamor frequencies.Evaluation of the parameters governing the relaxivity shows that it is limited by the average residence time of water in the first coordination sphere of GdIII.现在学习的是第17页，共19页Investigations to further improve the efficiency of calix4arene-based MRI contrast agents along these lines are in progress.现在学习的是第18页，共19页现在学习的是第19页，共19页