Fast-scanning small-angle X-ray scattering of hydrated biological cells

Due to their high penetration depth, X-rays enable us to obtain information from the interior of whole unsliced cells. Scanning small-angle X-ray scattering (SAXS), in particular, reveals real-space images in dark-field representation as well as structural information in reciprocal space. However, obtaining information on anisotropy and orientation from cells in an aqueous, close-to-physiological environment remains challenging. Here, we extend the recently introduced fast-scanning SAXS mode with short exposure times of a few milliseconds to such hydrated samples by combining a newly developed X-ray compatible microfluidic chamber and innovative data analysis that includes an effective noise-filtering method. This strategy enables the systematic analysis of radiation damage by quantifying the SAXS signal. Our results demonstrate that scanning SAXS can be used to obtain intracellular information of fixed-hydrated cells and the approach may in the future be applicable to living cells as well.