Particle Metrology Approach to Understanding How Storage Conditions Affect Long-Term Liposome Stability

Lipidnanoparticles are a generic type of nanomaterial with broadapplicability in medicine as drug delivery vehicles. Liposomes area subtype of lipid nanoparticles and, as a therapeutic platform, canbe loaded with a genetic material or pharmaceutical agents for useas drug treatments. An open question for these types of lipid nanoparticlesis what factor(s) affect the long-term stability of the particles.The stability of the particle is of great interest to understand andpredict the effective shelf-life and storage requirements. In thisreport, we detail a one-year study of liposome stability as a functionof lipid composition, buffer composition/pH, and storage temperature.This was done in aqueous solution without freezing. The effect oflipid composition is shown to be a critical factor when evaluatingstability of the measured particle size and number concentration.Other factors (i.e., storage temperature and buffer pH/composition)were shown to be less critical but still have some effect. The stabilityof these particles informs formulation and optimal storage requirementsand assists with future developmental planning of a NIST liposome-basedreference material. This work also highlights the complex nature oflong-term soft particle storage in biopharmaceutical applications.