Combination measurement shows distribution of metals in biological samples
With an advanced X-ray combination technique, scientists have traced nanocarriers for tuberculosis drugs within cells with very high precision. The method combines two sophisticated scanning X-ray measurements and can locate minute amounts of various metals in biological samples at very high resolution, as a team around DESY scientist Karolina Stachnik reports in the journal Scientific Reports. To illustrate its versatility, the researchers have also used the combination method to map the calcium content in human bone, an analysis that can benefit osteoporosis research.“Metals play key roles in numerous biological processes, from the oxygen transport in our red blood cells and the mineralisation of bones to the detrimental accumulation of metals in nerve cells as seen in diseases like Alzheimer’s,” explains Stachnik who works in the Center for Free-Electron Laser Science CFEL at DESY. High-energy X-rays make metals light up in fluorescence, a method that is very sensitive even to tiny amounts. “However, the X-ray fluorescence measurements usually do not show the ultrastructure of a cell, for example,” says DESY scientist Alke Meents who led the research. “If you want to exactly locate the metals within your sample, you have to combine the measurements with an imaging technique.” The ultrastructure comprises the details of the cell morphology that are not visible under an optical microscope.
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Image: Two agglomerates of antibiotic-loaded iron nanocontainers (red) in a macrophage. Credit: Stachnik et al., „Scientific Reports“, CC BY 4.0