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. A possible method to determine the precise position, as well as the shape, of a crystal, makes use of confocal optical microscopy, a method which allows reconstruction of the three-dimensional shape of an object. To explore this option, we have established a collaboration with Warren Zipfel (Cornell, Biomedical Engineering Dept.), an expert in confocal microscopy, and have hired a post-doc, Imran Khan, to construct and test a confocal system at one of the MacCHESS beamlines. Preliminary experiments have established that accurate crystal shapes can be determined using an off-line commercial confocal microscope (Zeiss LSM 510). Crystals can be studied both in crystallization trays and mounted in loops (as they are on the beamline), and may be imaged in either fluorescence or reflectance mode. Previous experiments (Gillilan &student) established that many protein crystals will readily take up fluorescent dye, with no apparent effect on crystal structure. Hence the fluorescence mode is relevant, and may be useful in distinguishing crystals from their surroundings. We are currently investigating the effects of various experimental parameters on image quality. Design of an on-line confocal system is nearly complete, major components have been purchased (laser source, lenses, scanning galvanometer), and we anticipate having a working prototype in late 2011.
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