The Moderna and Pfizer/BioNTech COVID-19 vaccines use lipid nanoparticles — basically spheres of fat molecules — to protect and deliver the messenger RNA that generates a vaccine recipient’s immune response to the SARS-CoV-2 virus. “Membrane proteins sit in a cell membrane, which is a lipid bilayer,” Meloni said. The lipid structures can fuse or aggregate, exposing any embedded membrane proteins or cargo to degradation. “One of the challenges in my field of research is that both membrane proteins and lipid bilayers are very delicate and intrinsically metastable, and we’re trying to combine them in order to understand how these proteins function,” Meloni said. “One of the keys to this research was identifying the buffer solution in which everything resides,” Gassensmith said.