A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

Thomas D. Murray, Artem Y. Lyubimov, Craig M. Ogata, Huy Vo, Monarin Uervirojnangkoorn, Axel T. Brunger, James M. Berger

Research output: Contribution to journalArticlepeer-review

Abstract

Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2μl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called 'fixed-target' sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessary to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10-15μm) loaded into the chips yielded a complete, high-resolution (<1.6Å) data set sufficient to determine a high-quality structure by molecular replacement. The features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.

Original languageEnglish (US)
Pages (from-to)1987-1997
Number of pages11
JournalActa Crystallographica Section D: Biological Crystallography
Volume71
DOIs
StatePublished - Oct 1 2015

Keywords

  • X-ray crystallography
  • XFEL
  • microcrystals
  • microfluidics
  • microfocus beamline
  • serial data collection
  • silicon nitride

ASJC Scopus subject areas

  • Structural Biology

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