Lipidic cubic nanoparticles (LCNP) are known as convenient biocompatible drug delivery systems, hence understanding their mode of interaction with lipidic membranes is of special interest. The interactions of monoolein-based LCNP with model lipidic membranes self-assembled at the air-water interface of a Langmuir trough has been investigated in our labs. Our results indicate that at high surface pressures the lipid layer is densely packed and that LCNP interactions lead to the exchange of the lipid molecules with the monolayer, whereas at low surface pressures the monolayer is less densely packed which allows the incorporation of LCNP material into the monolayer. Here we propose to monitor lipid exchange/delivery as well as the binding of LCNP in situ at a fluid interface for the first time in a short initial study using neutron reflectometry and isotopic contrast substitution on FIGARO. These results can significantly enhance our understanding of the molecular interactions between model membranes and LCNP as alternative, biocompatible drug delivery systems. This first study will pave the way for future work on factors effecting the release of anti-cancer drugs of interest to us.