The phospholipid micelles are non-trivial (trade secret) to make and it's the major reason why African nations and other countries have not been able to successfully create mRNA vaccines at scale.
A cell is a bundle of proteins wrapped in a membrane that's sort of an oil drop (or as another comment said, a fat bubble). In biology it's called a phospholipid bilayer. Fun fact you can actually "merge" cells together with the help of certain viruses. Drug delivery usually involves moving molecules though this phospholipid bilayer which involves all sorts of tricks. There are pores and receptors on the membrane that can selectively bind to different biochemical molecules and proteins. A good chunk of research in bioinformatics, chemoinformatics, quantum computing is focusing on simulating protein binding dynamics and protein-protein interactions on various levels so we can design drugs that can bind to the receptors we want. (Alphafold made this a lot easier to figure out how to go from a sequence of genetic material to a specific protein shape) A RNA vaccine is kinda like a virus in that it has to be taken into a so the cellular machinery (ribosomes) can build the protein that it codes for. So having a micelle (or nanoparticle, whatever you want to call it) that can get absorbed and merged into the cell that you are targeting specifically is a Big Deal.
A cell is a bundle of proteins wrapped in a membrane that's sort of an oil drop (or as another comment said, a fat bubble). In biology it's called a phospholipid bilayer. Fun fact you can actually "merge" cells together with the help of certain viruses. Drug delivery usually involves moving molecules though this phospholipid bilayer which involves all sorts of tricks. There are pores and receptors on the membrane that can selectively bind to different biochemical molecules and proteins. A good chunk of research in bioinformatics, chemoinformatics, quantum computing is focusing on simulating protein binding dynamics and protein-protein interactions on various levels so we can design drugs that can bind to the receptors we want. (Alphafold made this a lot easier to figure out how to go from a sequence of genetic material to a specific protein shape) A RNA vaccine is kinda like a virus in that it has to be taken into a so the cellular machinery (ribosomes) can build the protein that it codes for. So having a micelle (or nanoparticle, whatever you want to call it) that can get absorbed and merged into the cell that you are targeting specifically is a Big Deal.