In Vivo mRNA delivery and efficiency: All experiments with animals were approved by the Institutional Animal Care and Use Committee (IACUC) at Carnegie Mellon University under the protocol number IPROTO202400000004. Six-to 8-week-old Balb/c Mice were purchased from Charles River and allowed to acclimate to vivarium conditions for at least 3 days before experiments were performed. Mice were anesthetized and injected in the retro-orbital vein with mRPZ particles generated with Firefly Luciferase expressing mRNA. Before injection, particles were suspended in 5 µL of 200 proof ethanol and sonicated, then DPBS was added stepwise, with repeated sonication, until a final volume of 170 µL was achieved. The PEI control was prepared by complexing mRNA and linear 20 kDA PEI in a 5% sterile glucose solution for 15 min followed by retro-orbital injections. In vivo, JetRNA+ was prepared per the manufacturer's protocol. Luciferase expression kinetics were collected starting at 3 hours post-injection. Mice were injected with 110 µL of D-Luciferin (30 mg/mL in DPBS) and luminescence was measured 10 to 15 minutes post-injection using IVIS® (PerkinElmer, Waltham, MA). Particle bioavailability and biodistribution were assessed by sacrificing the mice after 12 and 6 hours, respectively, and harvesting the heart, lungs, spleen, pancreas, kidneys, and liver. The organs' fluorescence and luminescence were measured using the IVIS® system. Blood was collected from mice, then serum was isolated and assessed for nitrogen urea, creatine, alkaline phosphatase, aspartate transaminase, alanine transaminase, and zinc concentration. Note particles generated using 24 µg of mRNA were unexpectedly hazardous to mice at the injected concentration with 2 of 6 mice surviving. Additionally, particles that were poorly resuspended caused the death of 2 mice at 12 µg doses.