Biomolecules are both fascinating and inherently complex and thus need to be studied by an equally complex array of methods. Neutron scattering techniques are non-destructive, highly penetrating, do not require sample labelling tags and show strong differences in their sensitivity to hydrogen and its isotope deuterium. Thus, neutron scattering is a particularly suitable tool for the investigation of biological matter. Here, we discuss how neutrons - in particular small-angle neutron scattering (SANS) - at the Institut Laue-Langevin (ILL, Grenoble, France) contribute to biological sciences.
As an example, we use a recent effort by ILL scientists  geared towards obtaining a detailed understanding of SARS-CoV-2. Along with complementary lab methods, this study used neutron reflectometry, spectroscopy and SANS to investigate the roles of selected SARS-CoV-2 Spike fusion peptides (FPs) in cellular infection. Our study revealed a surprising difference in the biological significance of these peptides: the roles assumed by the FPs range from membrane disruption, dehydration of membrane lipids to fusogenic effects. Notably, this publication illustrates the importance of neutron scattering methods for biological questions, including those of fundamental, global importance.