Liposome stability and integrity

Liposomes are versatile drug nanocarriers with dominant biopharmaceutical properties associated with superior therapeutic effects and low toxicity. However, stability issues including self-aggregation, flocculation, coalescence or precipitation of liposomal vesicles, can affect the in vitro and in vivo properties of liposomes and, thus, their therapeutic efficacy. Monitoring membrane fluidity and integrity of liposomes, via assessing their physicochemical features, can shed light on liposome stability during manufacturing and storage period as well as upon in vivo administration. Toward liposome clinical utility, this chapter, initially, introduces the fundamental knowledge regarding liposomal membrane fluidity and integrity, and summarizes the gold standard methods commonly applied to assess membrane fluidity and integrity. In addition, different aspects regarding the physical, chemical and biological stability of liposomes are discussed, with emphasis on the well-established as well as novel stabilization strategies used to improve liposome physicochemical properties. The scientific research in the field as yet proves that physical and chemical stability of liposomes are critical factors for the translational application of lipid-based formulation, an observation that was considered during the production of mRNA vaccines for COVID-19 pandemic.