Preparation of mRNA-PEI@ZIF-8: Precursor solutions of zinc nitrate hexahydrate (11.9 mg mL -1 ) and 2-methylimidazole (13.15 mg mL -1 ) were prepared in ethanol. mRNA (1 mg mL -1 ), 1 µg, was aliquoted into a centrifuge tube and mixed with 10 µL of 2-methyl imidazole solution. After thoroughly mixing the mRNA, 1 µL of Linear 20 kDA polyethyleneimine (1-2 mg mL -1 ) was added and mixed thoroughly. This solution was allowed to incubate for 15 minutes. After incubation, 10 µL of zinc nitrate was added and mixed for 30 seconds. The solution was incubated at room temperature for 2 hours. Particles were isolated by centrifugation at 16,000 x g for 5 min and washed with ethanol two times. Particles were stored at -80˚C until use. Procedure has been successfully scaled using 24 µg of mRNA maintaining the same weight ratios and precursor volumes.