LNP size is influenced by several factors such as flow rate, concentration, and PEG-lipid concentration. Higher concentrations of lipids (> 10 mM) can lead to larger particles due to increased lipid availability for nanoparticle formation, while lower concentrations generally result in smaller particles. A higher flow rate of lipids can lead to smaller, more uniform particles due to faster mixing and rapid nanoparticle formation, while a lower flow rate often results in larger particles. PEG-lipids influence LNP size by affecting particle stability and aggregation. Higher PEG-lipid concentrations can help stabilize particles and reduce aggregation, often resulting in smaller, more uniform LNPs. In contrast, lower concentrations may lead to increased particle size and aggregation.