Title: X-ray fluorescence microscopy for life and environmental studies at the Advanced Photon Source

Abstract: Trace elements, particularly metals, play very important roles in a large variety of biological and environmental systems. Approximately 40% of all enzymes require certain trace metals as part of their catalytic centers. Hard X-ray fluorescence microscopy (XFM) is one of the most sensitive techniques for studying trace metals in complex systems, such as biological tissues, cells, soil aggregates, etc. In this presentation, I will discuss the XFM capabilities at the Advanced Photon Source (APS) of Argonne National Laboratory, which offer a range of spatial resolutions from 10s of microns to sub-100 nm, covering the needs of studies at multiple length scales. I will also introduce the Bionanoprobe (BNP) instrument, the first of its kind XFM instrument with cryogenic capabilities, dedicated to studying biological systems at a sub-cellular level. The cryogenic capabilities, including a cryogenic sample environment and cryogenic sample transfer mechanism, allow biological samples to be measured in their frozen hydrated state, where the ultrastructure and elemental distributions are preserved closest to their natural state. Over the past decade, we have implemented XFM tomography, ptychography imaging, and in-line optical fluorescence imaging capabilities at the BNP, enabling multi-modality analysis on the same platform. Currently, the second-generation BNP instrument is under development and scheduled to be completed in 2025, with the primary goal of utilizing the APS-Upgrade synchrotron source and delivering a 10 nm spatial resolution.

Bio: Dr. Si Chen is Physicist and Beamline Scientist at the Advanced Photon Source (APS) of Argonne National Laboratory. Her research focuses on elemental imaging for life and environmental sciences with hard X-ray fluorescence microscopy (XFM). Dr. Chen joined Argonne in 2011 and commissioned the Bionanoprobe (BNP) instrument, i.e., the first of its kind nanoscale XFM with cryogenic capabilities. She is currently leading the user program centered around the BNP, as well as the efforts for developing the next-generation XFM instrumentation. Prior to joining Argonne, she received her PhD in Materials Engineering at Dartmouth College, where she studied snow metamorphism.