SMALL-ANGLE MICRO DIFFRACTION OF BIOLOGICAL MATERIALS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Work over the last year has demonstrated that the BioCAT K-B mirror system be the basis of an effective and versatile system for medium and wide angle fiber diffraction from biological materials. Frequently with muscle systems, however, we are interested both low and wide angle information. Similarly, with collagenous systems (such as bone) it would be useful to see the low-angle information as well as the wide angle. The purpose of these studies was to see if the minimum d-spacing of the instrument could be pushed down to be suitable to collect low-angle information from muscle. Both 12 and 8 keV energies were tried, focused at both the sample and at the detector. The results indicated that very good results could be obtained from muscle at 8 keV, easily resolving 60 nm first order, focussed at either the detector or at the sample. We also discovered that far superior diffraction patterns from bone sections could be obtained by focusing at the sample (~10 micron focal spot) than can be obtained with conventional instrumentation. It appears with some further development it should be able to resolve the first order of collagen at 67 nm, which would be highly desirable for scanning micro-diffraction applications. These results also indicated that the same apparatus could be useful for time resolved SAXS and WAXS studies using micro-fluidic mixers.