Radicals and Polyradicals for Dynamic Nuclear Polarization

动态核极化的自由基和多自由基

• 批准号: 8432066
• 负责人: TIMOTHY M SWAGER
• 金额: $ 30.72万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8432066
• 关键词: Address; Anisotropy; Area; Biochemical; Biological; Biological Models; Bypass; Cell Nucleus; Collaborations; Coupled; Electrons; Evaluation; Fullerenes; Funding; Gel; Generations; Imaging Techniques; Investigation; Laboratories; Lead; Liquid substance; Magic; Magnetic Resonance; Magnetic Resonance Imaging; Magnetism; Methods; Mono-S; Nature; Nuclear; Nuclear Magnetic Resonance; Organic solvent product; Polymers; Process; Relative (related person); Research; Signal Transduction; Solid; Solutions; Space Perception; Structural Biochemistry; Structure; Testing; Water; base; crosslink; density; design; improved; instrumentation; interest; magnetic field; microwave electromagnetic radiation; next generation; novel; professor; research study; scaffold; solid state; success; theories

DESCRIPTION (provided by applicant): This proposal is focused on the synthesis of new molecules, polymers and gels to be used with dynamic nuclear polarization (DNP) to produce enhanced NMR signals. The PI has a continuing collaboration with Professor Robert G. Griffin of the Francis Bitter Magnet Laboratory for critical evaluation of DNP materials and DNP NMR applications. The DNP method makes use of spins associated with radicals to polarize the nuclear spins of the molecules of interest. Preliminary investigations with biradicals have shown that these molecules provide greatly enhanced signals in NMR spectra (observed enhancements of H 300 are obtained in magic angle spinning spectra of solids and H 400 in solution NMR spectra). The coupled biradical approach has allowed these high enhancements at lower concentrations than can be achieved with a mono-radical species. The lower concentrations minimize the broadening due to the paramagnetic radicals in the mixture. New improved biradicals and next generation polyradical-based fullerene structures will be synthesized and evaluated for their ability to polarize nuclear spins. Extended polyradical structures based upon polymers will be developed and evaluated for DNP activity. These latter materials will be converted into gels for the polarization of liquids and eventually DNP NMR structure studies. Anisotropic DNP gels will be produced and offer new opportunities for NMR structure determination. This research is directed at producing materials that will lead to improved analysis of the structures of biological molecules by nuclear magnetic resonance and eventually novel imaging techniques for MRI. Magnetic resonance methods suffer from low sensitivity and dynamic nuclear polarization addresses this limitation. In this process electrons are excited by microwaves and transfer magnetic polarization to nuclei to produce large sensitivity enhancements.

描述（由申请人提供）：该建议集中于与动态核极化（DNP）一起使用的新分子，聚合物和凝胶的合成，以产生增强的NMR信号。 PI与Francis Bitter Magnet Laboratory的Robert G. Griffin教授进行了持续的合作，以对DNP材料和DNP NMR应用进行批判性评估。 DNP方法利用与自由基相关的旋转来使目标分子的核自旋两极。对Biradicals的初步研究表明，这些分子在NMR光谱中提供了大大增强的信号（观察到的H 300的增强是在固体的魔法角度旋光中获得的，在溶液NMR光谱中获得了H 400）。耦合的Biradical方法使这些高浓度的高增强量要比单个自由基物种所能达到的浓度较低。较低的浓度最大程度地减少了由于混合物中顺磁性自由基而引起的拓宽。将合成并评估新的改进的Biradicals和下一代基于多性恋的富勒烯结构，并评估它们的核自旋的能力。将开发并评估基于聚合物的扩展的多性自由基结构，以评估DNP活性。这些后一种材料将转化为凝胶，以进行液体的极化和最终的DNP NMR结构研究。各向异性DNP凝胶将产生，并为NMR结构确定提供新的机会。这项研究旨在生产材料，从而通过核磁共振和最终用于MRI的新型成像技术来改善对生物分子结构的分析。磁共振方法的灵敏度低，动态核极化解决了这一限制。在此过程中，电子通过微波激发，并将磁极化转移到核中以产生较大的灵敏度增强。