The currently accepted mode of action for LNP delivery is that, upon injection into the bloodstream, a corona shell is formed around the particle, where the APO E peptide is an essential component in addition to albumin. APO E is responsible for LNP endocytosis into the cell. The resulting endosome formed with the LNP inside will then mature, resulting in a pH drop from 7 to around 6-5. Upon the pH drop, several of the ILs in the LNP become protonated which is believed to induce structural changes in the LNP that enable particle fusion with the endosomal membrane and the eventual release of its cargo into the cytosol. In the case of mRNA cargo, as in the COVID vaccines, the mRNA is then transcribed by the ribosome .