MICRODIFFRACTION DEVELOPMENT & MICRODIFFRACTION STUDIES OF CARTILAGE & COLLAGEN

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。BioCAT的微探针能力的发展已被提议为目前的NIH拨款周期。BioCAT设备的一个重点领域是复杂生物材料的静态和时间分辨纤维衍射测量。其中一个区域是肌腱、软骨和皮肤中有序小区域内的胶原纤维结构。在这里，我们报告了初步的微衍射实验，证明了这种研究在18ID上的可行性。使用KB反射镜系统（Xradia Inc.）产生6x6 um^2的聚焦光束，距离最后一个反射镜300 mm，入射光束被准直到100x100微米以减少发散。系统对准来自Si（111）单色仪的12 keV单色光束。在样品位置（距离第二个KB反射镜20 cm处）获得的光束尺寸为6 x 6微米FWHM。样品用低温流保存在低温下以防止辐射损伤。我们能够从大鼠尾胶原（I型）和软骨组织（II型）中分辨出紧密间隔（1/67 mm）的胶原子午反射。我们预计该装置将成为研究许多结缔组织类型中基于胶原蛋白的结构的通用工具，并为研究薄组织标本中其他局部有序结构（例如淀粉样蛋白聚集体）开辟了可能性。

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. The development of BioCAT's microprobe capabilities has been proposed for the current NIH grant cycle. A thrust area at the BioCAT facility is static and time-resolved fiber-diffraction measurements from complex biological materials. One of these areas is the structure of collagenous fibers within small ordered regions in tendons, cartilage, and skin. Here we report on preliminary microdiffraction experiments demonstrating the feasibility of such studies on 18ID. A KB mirror system (Xradia Inc.) was used to produce a 6x6 um^2 focused beam, 300 mm from the last mirror, and the incident beam was collimated to 100x100 microns to reduce the divergence. The system was aligned to a 12 keV monochromatic beam from our Si(111) monochromator. The beam size obtained was 6 x 6 micron FWHM at the sample position (20 cm from the second KB mirror). The samples were kept at low temperature using a cryostream to prevent radiation damage. We were able to resolve the closely spaced (1/67 mm) collagen meridional reflections from rat-tail collagen (type I) and from cartilage tissue (type II). We anticipate that this setup will be a versatile tool for studying collagen-based structures in a number of connective tissue types, as well as open up the possibility of studying other locally ordered structures (e.g. Amyloid aggregates) in thin tissue specimens.