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

Abstract 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 few milliseconds to such hydrated samples by combining a newly developed, X-ray compatible microfluidic sample 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. Synopsis Fast scanning SAXS on biological cells in aqueous environment reveals intracellular anisotropy and orientation and allows for systematic assessment of radiation damage caused by the measurements.