Method for preparing PEI-lipid nanoparticles used for delivering a mRNA vaccine and transfecting stem cells

A method of preparing polyethyleneimine-lipid nanoparticles (PEI-LNPs) for delivering an mRNA vaccine and transfecting stem cells, comprising the following specific steps:

• 1) adding anhydride to a PEI solution to produce polycarboxylic acid and PEI-LNPs, wherein the anhydride is C8-C18 alkyl anhydride;
• 2) dissolving the PEI-LNPs obtained in step 1, together with DPPC, DPPG, DPPE-PEG-COOH and cholesterol in chloroform to form a chloroform solution, dissolving cGAMP in a sterile water to form a cGAMP solution and then adding the cGAMP solution to the chloroform solution, and performing vacuum ultrasonication for 30 min and then vacuum evaporation to remove the chloroform and obtain a PEI-LNPs mixture;
• 3) adding PBS to the PEI-LNPs mixture obtained in step 2 for hydration, and then performing ultrasonication for 20 min to obtain a liposome solution;
• and
• 4) adding EDC/NHS to the liposome solution obtained in step 3 to perform a reaction for 15 min, then adding an mRNA to form a mixed solution, and stirring the mixed solution at a room temperature for 1 h to obtain a bionic virus nanovaccine.