CryoMAS Probes for Order-of-Magnitude Advance in S/N in NMR of Solids

描述（由申请人提供）：魔角旋转（MAS）被成千上万的核磁共振（NMR）研究人员用于大分子结构测定、膜蛋白、催化和有机金属配合物等领域。三十多年来，高分辨率核磁共振（HR）已经成为一种领先的分析技术，用于在均相系统中所有类型的分子的结构和功能阐明，无论大小。最近，HR-MAS已被用于将该技术扩展到非均匀系统，如人类和动物组织。恶性乳腺癌组织的1H HR-MAS光谱显示，与非恶性乳腺组织相比，磷胆碱水平显著升高，如果HR-MAS探头的信噪比（SNR）能够充分提高，似乎可以识别出许多其他明确的标志物。用于液体的HR核磁共振探针已经可以使用低温冷却的样品线圈，由于其信噪比的四倍提高，这些线圈正在彻底改变核磁共振领域。使用几种常见类型的CryoMAS探针，包括1H/13C/15N和1H/X，可以实现更大的信噪比改善。到目前为止，我们的工作表明，在上述两种探针的MAS实验中，通过将线圈和电路元件低温冷却至25 K，同时将样品保持在室温下，信噪比提高了五倍。预计在第二阶段的进一步进展中，信噪比将大幅增加。这些进步将包括(1)新型线圈技术，使高磁场下25 K的谐振器质量因子Q增加50%以上，(2)密封式旋转器设计的改进，使冷冻线圈的磁填充因子提高25%，(3)400-1000 MHz范围内高压陶瓷电容器的Q增加了两倍。(4)在三共振CryoMAS探针中实现超过75 kHz 1H去耦磁场强度至少为11.7 t的能力，在样品温度低至30 K时的旋转也将得到实质性的改进，并且将增加毫米波辐照的规定，以使动态核极化（DNP）易于添加。在MAS DNP中，将样品温度从90k降低到40k，通常可以将DNP实验中的信噪比提高一个数量级。基于增强模式伪晶高电子迁移率晶体管（E-PHEMT）的低温冷却前置放大器噪声系数（NF）的进一步降低将进一步提高信噪比。关键词：固体核磁共振探针，低温探针，HR-MAS，癌症诊断测试，分子结构，低温前放大器，动态核极化（DNP）项目简介：核磁共振（NMR）已经成为确定生物学，化学和医学中复杂分子结构的最有效的分析工具之一，但核磁共振技术在不溶于适当液体的大分子中取得的成功有限。本文提出的仪器开发，称为CryoMAS核磁共振探针，将把非常昂贵的核磁共振光谱仪所需的时间减少20到100倍（从几周或几天到几小时或几分钟），从而使确定成千上万的生物和化学上重要的大分子的结构成为现实，这些大分子的结构目前是未知的。这对公共卫生、催化剂和酶的药物开发非常重要，仅举几例。商业/市场潜力：全球安装了5000多个高场核磁共振系统，其中许多在研究型医院；核磁共振设备年销售额目前超过3亿美元。HR-MAS在乳腺癌的明确诊断测试中显示出相当大的前景。提出的MAS探针的发展也将引起成千上万化学和生物化学领域的核磁共振研究人员的兴趣。在二期完成后的15年内，CryoMAS探针的市场潜力几乎肯定会超过1亿美元，甚至可能超过3亿美元。

DESCRIPTION (provided by applicant): Magic Angle Spinning (MAS) is utilized by thousands of Nuclear Magnetic Resonance (NMR) researchers in fields such as macromolecule structure determination, membrane proteins, catalysis, and organo-metallo-complexes. For over three decades, High-Resolution (HR) NMR has been a leading analytical technique for structure and function elucidation of molecules of all types, large and small, in homogeneous systems. More recently, HR-MAS has been used to extend the technique to inhomogeneous systems, such as human and animal tissues. The 1H HR-MAS spectrum of malignant breast cancer tissue shows dramatically increased levels of phosphocholine compared to nonmalignant breast tissue, and it appears likely that many other unambiguous markers can be identified for other pathologies if the signal to noise ratio (SNR) of the HR-MAS probe can be increased sufficiently. HR NMR probes for liquids have become available with cryogenically cooled sample coils that are revolutionizing the field of NMR owing to their factor-of-four improvement in SNR. Even greater improvements in SNR can be achieved with CryoMAS probes of several common types, including 1H/13C/15N and 1H/X. Our work thus far demonstrated about a factor-of-five improvement in SNR in MAS experiments in probes of both of the above types by cryogenically cooling the coils and circuit elements to 25 K while the sample was maintained at room temperature. A substantial additional increase in SNR is expected from a combination of further advances during the Phase II. These advances will include (1) novel coil technology enabling more than a 50% increase in resonator quality factor Q at 25 K in high magnetic fields, (2) refinements in a hermetically sealed spinner design enabling a 25% improvement in magnetic filling factor of the cryocoils, (3) a factor of two increase in the Q of HV ceramic capacitors in the 400-1000 MHz range, and (4) ability to achieve over 75 kHz 1H decoupling field strength in a triple-resonance CryoMAS probe to at least 11.7 T. Substantial improvements in spinning at sample temperatures down to 30 K will also be developed, and provisions for millimeter-wave irradiation will be added to enable Dynamic Nuclear Polarization (DNP) to be easily added. Reducing the sample temperature from 90 K to 40 K in MAS DNP is expected to often in- crease S/N in DNP experiments by an order of magnitude. Additional improvements in S/N will come from further progress in reduction of noise figure (NF) of cryogenically cooled preamps based on the Enhancement mode Pseudomorphic High Electron Mobility Transistors (E-PHEMT). Key Words: solids NMR probes, cryoprobes, HR-MAS, cancer diagnostic tests, molecular structures, cryogenic preamps, dynamic nuclear polarization (DNP) Project Narrative: Nuclear magnetic resonance (NMR) has been one of the most effective analytical tools for determining the structure of complex molecules in biology, chemistry, and medicine, but the NMR technique has had limited success for the very large molecules that are not soluble in suitable liquids. The instrument development proposed herein, called a CryoMAS NMR probe, will reduce the amount of time needed on very expensive NMR spectrometers by a factor of 20 to 100 (from weeks or days to hours or minutes) and thus make it practical to determine the structures of hundreds of thousands of biologically and chemically important macro-molecules for which structures are currently unknown. This is important to drug developments for public health, catalysts, and enzymes, to name but a few. Business/market potential: There are over 5,000 high-field NMR systems installed world-wide, many of which are at research hospitals; and annual NMR equipment sales are currently over $300M. HR-MAS has shown considerable promise for unambiguous diagnostic testing for breast cancer. The proposed MAS probe development would also be of interest to thousands of NMR researchers in chemistry and biochemistry. Market potential of CryoMAS probes over the 15 years following completion of the Phase II almost certainly exceeds $100M and may exceed $300M. PUBLIC HEALTH RELEVANCE: Nuclear magnetic resonance (NMR) has been one of the most effective analytical tools for determining the structure of complex molecules in biology, chemistry, and medicine, but the NMR technique has had limited success for the very large molecules that are not soluble in suitable liquids. The instrument development proposed herein, called a CryoMAS NMR probe, will reduce the amount of time needed on very expensive NMR spectrometers by a factor of 20 to 100 (from weeks or days to hours or minutes) and thus make it practical to determine the structures of hundreds of thousands of biologically and chemically important macro-molecules for which structures are currently unknown. This is important to drug developments for public health, catalysts, and enzymes, to name but a few. Business/market potential: There are over 5,000 high-field NMR systems installed world-wide, many of which are at research hospitals; and annual NMR equipment sales are currently over $300M. HR-MAS has shown considerable promise for unambiguous diagnostic testing for breast cancer. The proposed MAS probe development would also be of interest to thousands of NMR researchers in chemistry and biochemistry. Market potential of CryoMAS probes over the 15 years following completion of the Phase II almost certainly exceeds $100M and may exceed $300M.