MICROTOME METHODS FOR ALIGNED SAMPLES FOR HIGH FIELD ESR

高场 ESR 对齐样品的切片机方法

• 批准号: 7420480
• 负责人: BORIS G DZIKOVSKI
• 金额: $ 2.38万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7420480
• 关键词: biomedical equipment; magnetic field; orientation; sectioning

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A combination of isopotential spin-dry centrifugation (ISDU) and microtome techniques is used to record high field/high frequency (HF/HF) ESR spectra corresponding to different orientations of the membrane normal relative to the magnetic field. At X-band (~ 9.5 GHz) one can get ESR spectra for different orientations of the membrane normal relative to the magnetic field merely by rotating the sample in the resonator. The method is not applicable at higher frequencies. Due to unavoidable dielectric losses, a successful HF experiment requires thin ( 100 mkm) flat samples placed at a node of the millimeter wave E-field. For the standard fixed resonator geometry, the sample normal is parallel to the applied magnetic field B0. However, applying microtome techniques to ISDU aligned samples offers an opportunity to combine excellent orientational resolution, one of the main virtues of high-field ESR, with the ability to study aligned membrane samples in various orientations. The technique is used to prepare thin slices of various, controllable membrane orientations, suitable for HF/HF ESR. The X-band spectra of the slices are shown identical to the spectra obtained by rotating corresponding ISDU samples in the resonator. Examples of spin-labeled Gramicidin A and cholestane spin label in the aligned DPPC membrane illustrate applications of the technique and some virtues of HFHF ESR on aligned membranes vs. X-band.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。使用等电位旋转干燥离心（ISDU）和切片机技术的组合来记录高场/高频（HF/HF）ESR谱，其对应于膜相对于磁场的法线的不同取向。在X波段（~ 9.5 GHz），只需在谐振器中旋转样品，即可获得膜垂直于磁场的不同取向的ESR谱。该方法不适用于更高的频率。由于不可避免的介电损耗，一个成功的HF实验需要薄（100 mkm）的平面样品放置在一个节点的毫米波E场。对于标准固定谐振器几何形状，样品法线平行于所施加的磁场B 0。然而，应用切片机技术ISDU对齐的样品提供了一个机会，联合收割机优秀的取向分辨率，高场ESR的主要优点之一，与研究对齐的膜样品在各种方向的能力。该技术用于制备各种薄膜取向的薄片，适用于HF/HF ESR。切片的X波段光谱与通过在谐振器中旋转相应的ISDU样品获得的光谱相同。自旋标记短杆菌肽A和胆甾烷自旋标记物在定向DPPC膜上的实例说明了该技术的应用以及HFHF ESR在定向膜上与X带相比的一些优点。