Advantages of intermediate X-ray energies in Zernike phase contrast X-ray microscopy

Zhili Wang, Kun Gao, Jian Chen, Youli Hong, Xin Ge, Dajiang Wang, Zhiyun Pan, Peiping Zhu, Wenbing Yun, Chris Jacobsen, Ziyu Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Understanding the hierarchical organizations of molecules and organelles within the interior of large eukaryotic cells is a challenge of fundamental interest in cell biology. Light microscopy is a powerful tool for observations of the dynamics of live cells, its resolution attainable is limited and insufficient. While electron microscopy can produce images with astonishing resolution and clarity of ultra-thin (<1μm thick) sections of biological specimens, many questions involve the three-dimensional organization of a cell or the interconnectivity of cells. X-ray microscopy offers superior imaging resolution compared to light microscopy, and unique capability of nondestructive three-dimensional imaging of hydrated unstained biological cells, complementary to existing light and electron microscopy.Until now, X-ray microscopes operating in the "water window" energy range between carbon and oxygen k-shell absorption edges have produced outstanding 3D images of cryo-preserved cells. The relatively low X-ray energy (<540. eV) of the water window imposes two important limitations: limited penetration (<10μm) not suitable for imaging larger cells or tissues, and small depth of focus (DoF) for high resolution 3D imaging (e.g., ~. 1. μm DoF for 20. nm resolution). An X-ray microscope operating at intermediate energy around 2.5. keV using Zernike phase contrast can overcome the above limitations and reduces radiation dose to the specimen. Using a hydrated model cell with an average chemical composition reported in literature, we calculated the image contrast and the radiation dose for absorption and Zernike phase contrast, respectively. The results show that an X-ray microscope operating at ~. 2.5. keV using Zernike phase contrast offers substantial advantages in terms of specimen size, radiation dose and depth-of-focus.

Original languageEnglish (US)
Pages (from-to)387-392
Number of pages6
JournalBiotechnology Advances
Issue number3
StatePublished - May 2013


  • Depth-of-focus
  • Intermediate energy
  • Radiation dose
  • Tomography
  • X-ray microscopy
  • Zernike phase contrast

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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