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Title: Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ~90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. Finally, this combined approach offers a way to study the role of trace elements in their structural context.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [3] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. La Trobe Univ., Melbourne, VIC (Australia); Commonwealth Scientific and Industrial Research Organization Manufacturing Flagship, Parkville, VIC (Australia)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; 1R01GM104530; 1S10RR029272-01
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 8; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Institutes of Health (NIH); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ptychography; X-ray fluorescence microscopy; cryogenic biological samples
OSTI Identifier:
1235500
Alternate Identifier(s):
OSTI ID: 1215636; OSTI ID: 1346725