Chemidoc 219 xrs system

To evaluate the complexation of mRNA and MP₁₀₀₀-LPs, 1 μg free mRNA and MP₁₀₀₀-LPX (containing 1 μg mRNA) were diluted with RNase-free water. Then NorthernMax^® formaldehyde load dye containing ethidium bromide (50 μg/mL) was added and mixed. After incubating the samples for 10 min in 65°C, the samples were loaded into a 1% denaturing formaldehyde agarose gel in precooled MOPS buffer. The gel was run for 20 min at 180 V and analyzed using a molecular imager, ChemiDocTM 219 XRS system (Bio-Rad, United States). RNA Millennium^TM markers (Ambion) with bands at a range of 0.5–9 kb was included to provide size determination of the mRNA.

A gel electrophoresis retardation assay was performed to evaluate the mRNA‐binding ability of the complexation of mRNA and LNP at different time points. Free mRNA (0.5 µg) and LNP@GFP‐mRNA (containing 0.5 µg mRNA) were diluted with RNase‐free water. The running gel parameters were set to 120 for 20 min, and this electrophoresis process was stopped until the indicator reached 2/3 of the electrophoresis gel. The results were analyzed using a ChemiDocTM 219 XRS system (Gel Doc 2000, Bio–Rad Laboratories, Hercules, USA).