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Overhauser Effect Essay

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Dynamic nuclear polarization (DNP) through Overhauser effect has several applications including Overhauser enhanced magnetic resonance imaging (OMRI) and considerable interest in the field of biomedical imaging [1-8]. Recent experiments on common free radicals are often used such as family of nitroxide free radicals, and several studies have done to determine which derivatives give the best signal enhancement [7-11]. For low-frequency in vivo electron spin resonance imaging (ESRI) and as contrast agents for OMRI, nitroxyl radicals have been used as spin probes [4,12], and successfully obtained images of tissue water protons in the vicinity of paramagnetic radicals and achieved in vivo imaging [13].Recently, isotropically labeling nitroxyl spin probes used to investigate redox sensitive molecular probes for …show more content…

In ESRI, both spatial and the spectral information of the exogenously administered spin probes are obtained. Hence, ESRI often presents the in vivo of the spin probes without complementary anatomical information. In contrast, Magnetic resonance imaging (MRI) gives superior anatomic information. OMRI is a double resonance technique that depends on the Overhauser effect. It coupled the advantages of MRI with the sensitivity of ESR, by making use of the Overhauser effect [4,16]. In this phenomenon, the relatively stronger magnetic moment of the electron is used to transfer of polarization from unpaired electron spins to the coupled proton spins results in the enhancement of the NMR signal in regions of the sample containing free-radical, revealing its spatial distribution in the final image. This leads to the possibility of NMR imaging at very low magnetic fields [4,9,12,17-26]. These advantages motivated us to explore, for the first time, the capability of OMRI for simultaneous molecular imaging of redox reactions using nitroxyl radicals. Nitroxyl radicals have been widely used as spin

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