Exploring interactions between lipid membranes and nanoparticles through neutron and X-ray reflectometry techniques

Nanoparticle–membrane interactions play a pivotal role in various biological and biomedical processes, making their study essential for understanding nanoparticle behavior in complex biological systems. In this chapter, we explore the application of neutron and X-ray reflectometry (NR and XRR) techniques in investigating the structural dynamics and functional consequences of nanoparticle–membrane interactions, with a particular focus on soft and hard nanoparticles interacting with lipid membranes. We begin by discussing the advantages of NR and XRR techniques, which provide valuable insights into the internal structure of lipid membranes, the spatial distribution of nanoparticles in the proximity or within solid supported lipid bilayers (SLBs). Furthermore, we delve into the unique information obtained through NR experiments, where the contrast variation method allows for the quantification of lipid, water, and nanoparticle components. This enables the differentiation between structural modifications induced by nanoparticle incorporation and the formation of water-filled pores or membrane disruption. Several case studies are presented, highlighting the use of NR and XRR techniques to discuss the influence of nanoparticle surface charge, shape, and composition on the mode of interaction, membrane integrity, and lipid organization. Additionally, the role of membrane complexity, including the presence of natural lipid and protein components, in shaping nanoparticle–membrane interactions is emphasized. Overall, this chapter demonstrates the significance of neutron and X-ray reflectometry techniques in unraveling the intricate details of nanoparticle–membrane interactions. The insights gained from these studies contribute to the development of safe and effective nanoparticle-based therapeutics, as well as the understanding of fundamental biological processes at the nanoscale.