In situ radiation damage tracking during scanning small-angle X-ray scattering

Due to the high penetration power of X-rays, X-ray imaging techniques have been employed to image cellular architecture. Among these techniques, scanning small-angle X-ray scattering (SAXS) is a powerful method for investigating ordered structures within cells. With the recent advent of high-brilliance synchrotron sources, nano-focused X-rays and fast scanning modes, scanning SAXS can now provide structural information from hydrated cells in liquid environments in little time. However, the high photon flux results in an increased dose and pronounced radiation damage to the intracellular structures. Therefore, strategies are required to monitor and quantitatively analyze the extent of damage. Here, we present a multimodal approach that employs an on-axis, high-speed, brightfield microscope to monitor cellular damage during scanning. This microscope is integrated into the scanning SAXS setup at ID13 of ESRF and records images in synchrony with SAXS data acquisition. We are able to observe and quantitatively track changes in cellular morphology \textit{in situ} and thereby obtain complementary information to that provided by scanning SAXS measurements. Our approach opens up the potential for a multifaceted investigation of radiation damage to biological cells and other sample types.