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.
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