Membranes of vertically aligned carbon nanotubes (VaCNT) can be used to clean or desalinate water at high flow rate and low pressure. Recently, researchers of Karlsruhe Institute of Technology (KIT) and partners carried out steroid hormone adsorption experiments to study the interplay of forces in the small pores. They found that VaCNT of specific pore geometry and pore surface structure are suited for use as highly selective membranes. The researchers report in Nature Communications. (DOI: 10.1038/s41467-024-44883-2)