| AVS 62nd International Symposium & Exhibition | |
| Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic | Monday Sessions |
| Session SA-MoM |
| Session: | Imaging and Nanodiffraction (8:20-10:00 am) & Novel Insights in Correlated Materials, Organic Materials and 2D Solids (10:40 am -12:00 pm) |
| Presenter: | Gijs van der Schot, Uppsala University, Sweden |
| Correspondent: | Click to Email |
Imaging live cells at a resolution higher than achieved using optical microscopy is a challenge. Ultra-fast coherent diffractive imaging1 with X-ray free-electron lasers (XFELs) has the potential to achieve sub-nanometer resolution on micron-sized living cells2. Our container-free injection method can introduce a beam of live cyanobacteria into the micron-sized focus of the Linac Coherent Light Source (LCLS) to record diffraction patterns from individual cells, with low noise at high hit rates3. We used iterative phase retrieval4-6 to derive two-dimensional projection images directly from the diffraction patterns. Synthetic X-ray Nomarski images7, calculated from the complex-valued reconstructions, show cells in a similar manner to what one would expect to see using a Nomarski microscope, only at higher resolution than currently available. In a first experiment, we collected diffraction patterns to 33-46 nm full-period resolution, and reconstructed the exit wave front to 76 nm resolution3. In a second experiment, we demonstrate that it is indeed possible to record diffraction data to nanometer resolution on live cells with an intense, ultra-short X-ray pulse as predicted earlier2,3. These results are encouraging, and future developments to the XFELs and improvements to the X-ray area-detectors will bring sub-nanometer resolution reconstructions of living cells within reach.
We thank the Swedish Research Council, the Knut and Alice Wallenberg Foundation, the European Research Council, the Röntgen-Ångström Cluster, and Stiftelsen Olle Engkvist Byggmästare for supporting this work.
References
1. Neutze, R., Wouts, R., van der Spoel, D., Weckert, E. & Hajdu, J. Potential for biomolecular imaging with femtosecond X-ray pulses. Nature406, 752-757 (2000).
2. Bergh, M. et al. Feasibility of imaging living cells at subnanometer resolutions by ultrafast X-ray diffraction. Q. Rev. Biophys. 41, 181-204 (2008).
3. van der Schot, G. et al. Imaging single cells in a beam of live cyanobacteria with an X-ray laser. Nat. Commun. 6, 5704 (2015).
4. Gerchberg, R.W. & Saxton, W.O. Practical Algorithm for Determination of Phase from Image and Diffraction Plane Pictures. Optik35, 237-246 (1972).
5. Fienup, J.R. Reconstruction of an Object from Modulus of Its Fourier-Transform. Opt. Lett.3, 27-29 (1978).
6. Luke, D.R. Relaxed averaged alternating reflections for diffraction imaging. Inverse Probl.21, 37-50 (2005).
7. Paganin, D. et al. X-ray omni microscopy. J. Microsc.214, 315-327 (2004).