Learn how scientists use X-rays to study bones at a molecular level
![A drawing of swordfish and a bubble containing a drawing of a molecular model. Both on blue background representing water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame1_Website.jpg)
Did you know that swordfish use their long sword as a tool for hunting? Rather than using it like a sword, they use it as a club to stun their prey. However, despite being under heavy load during hunting, it doesn't break easily.
Scientists explore this material strength using various experimental techniques, such as SAXS. Because the swordfish sword is in many ways similar to the bones of older human adults, it can help in understanding human bone ageing.
![A drawing showing an X-ray image of a swordfish's sword and leg bones of a diving human adult. The blue background represents water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame2_Website-1024x614.jpg)
Bio-SAXS: biological small-angle X-ray scattering
Bio-SAXS lets scientists determine the shape and dynamics of proteins and other bio-molecules using X-rays.
X-ray experiments take place at specialised testing stations called beamlines in synchrotrons.
Bio-SAXS is very versatile - it can be used for samples in almost any form, e.g. liquid or solid.
During a bio-SAXS experiment, X-rays are shot at a biological sample and get scattered in a unique pattern as they pass through it. This pattern depends on the types of atoms and how they are arranged inside the sample.
![A drawing of a cuvette filled with a liquid sample containing floating molecules. An X-ray passes through it and scatters into a circular pattern of tiny dots. The blue background represents water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame3_Website-1024x614.jpg)
Scientists then analyse the scattering pattern to 'peek inside' a material to work out the 3D structures of the molecules.
Bio-SAXS is very versatile - it can be used for samples in almost any form, e.g. liquid or solid. It allows studying how molecules change their structure in different conditions, and how they interact with each other. The molecular structures and interactions are what give materials their unique properties.
![A drawing showing a bubble containing SAXS pattern and another bubble with a molecular model derived from that pattern. The blue background represents water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame4_Website-1024x614.jpg)
Understanding human bone ageing using the swordfish sword
Bio-SAXS has previously enabled scientists to examine the structure of mineral particles in the swordfish sword at both the young bone at its base and the old bone at its tip. Studying this could help us understand better why and how bones in older adults deteriorate with time.
![A zoom into the swordfish sword at its tip and at its base shows more porosity and lower mineralisation in the bone structure at the base on the sword than at the tip. The blue background represents water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame5_Website-1024x614.jpg)
Other applications of bio-SAXS
Bio-SAXS helps scientists address other questions as well:
- Detect crystals growing inside cells
![A drawing of four bubbles, each representing a different application of bio-SAXS. First bubble: two different molecular structures at different temperatures. Second bubble: a lipid nanoparticle. Third bubble: plastic bag in the water falls apart into tiny pieces. Fourth bubble: cells with elongated orange crystals inside them. The blue background represents water.](https://www.embl.org/news/wp-content/uploads/2023/09/13062023_SAXSExplainer_Frame6_Website-1024x614.jpg)