Transfection: The particles were resuspended in 10 µL of ethanol and sonicated for 5 min then resuspended in Opti-MEM to a final concentration of 10 ng mRNA/µL. The particles were added to cells in a 96-well plate using 100 ng per well. Lipofectamine 2000 and Messenger Max were prepared per the manufacturer's protocol. mRNA-PEI complexes were prepared by suspending mRNA and PEI separately in Opti-MEM then mixing both solutions and incubating for 15 mins. Cells were incubated with particles for 48 hours, fixed using 4% paraformaldehyde in PBS, permeabilized with a 0.1% triton X-100 solution, and stained with DAPI. A lipofectamine-positive control was used. The fluorescence intensity was measured using a SpectraMax i3 plate reader at 475/515 nm for eGFP and 350/460 nm for DAPI. Imaging was performed using a Thermofisher EVOS M7000 with a DAPI, Cy5, and GFP filter cube. Due to Cy5 interrupting the expression of eGFP, Cy5-tagged eGFP mRNA was mixed with untagged eGFP mRNA in a 1:10 ratio.