Mapping biological composition through quantitative phase and absorption X-ray ptychography

Abstract

Isolating compositional information in biological X-ray imaging can be problematic as such information is conflated with thickness and density variations when viewing in projection through a sample. We demonstrate an effective method for identifying variations in material composition by simultaneously using the quantitative phase and magnitude images provided through soft X-ray ptychography. Using this approach we show significantly increased contrast and improved reliability of the identification of intracellular features from uncharacterised samples. While demonstrated for X-ray ptychography, this method is immediately applicable to electron and optical microscopy methods where the complex transmission function of the sample is recovered.

Multimodality hard-x-ray imaging of a chromosome with nanoscale spatial resolution

“…Hence, their ratio, which cancels the unknown thickness, leads to a novel type of contrast for composition ( Fig. 2j ) that has been successfully applied to studies of different type of samples before 21 27 28 29 . Ag came from the precursor used in the preparation process of the platinum blue stain 30 and deposits have been previously seen 31 (see methods).…”

Multi-slice ptychography with large numerical aperture multilayer Laue lenses

“…Since its first demonstration [12], the achieved focus size has been steadily improved to sub-10 nm scale with flat or wedged MLLs [13][14][15][16][17][18][19]. Integrating scanning probe microscopy with ptychography gains accumulating popularity for its multi-modality imaging capability with high spatial resolution [20][21][22]. The throughput of this approach was further enhanced by operating in the on-the-fly scan mode [23][24][25][26].…”

Molar concentration from sequential 2-D water-window X-ray ptychography and X-ray fluorescence in hydrated cells

“…MEFs are migrating cells, and as such have very fine features such as filopodia which they use to sense the surrounding environment and guide their movement. Filopodia are between 100 and 300 nm thick 32 , and have not previously been seen in X-ray diffraction measurements, most likely due to harsh preparation methods 19 . However, by sealing the cells in a fully hydrated environment, these fine features can be easily seen, as shown in Fig.…”

“…On close inspection, it can be seen that the bends in the filopodia are often adjacent to small X-ray dense areas on the substrate. The scattering quotient, f q , which is characteristic of composition is expressed as 19 …”

“…Scanning CDI methods, herein referred to generally as ptychography, allow specimens larger than the extent of a single X-ray probe to be imaged with fewer artefacts 10 11 12 , while providing directly quantitative information about the specimen 1 8 13 14 . Current ptychography techniques have demonstrated that artefacts can be suppressed virtually entirely 15 16 17 18 , with any artefacts remaining in cellular ptychography due to the preparation of the specimen rather than inherent to the technique 19 . To realise the potential of X-ray ptychography for biological applications, it is therefore necessary to avoid the structural and imaging artefacts caused by drying and or freezing 20 21 .…”