A Liposomes as a Novel Drug Delivery System: Formulation, Characterization, and Therapeutic Applications

Liposomes are among the most extensively investigated and clinically validated nanocarrier-based drug delivery systems, owing to their unique structural characteristics, biocompatibility, and ability to encapsulate a wide variety of therapeutic agents. Structurally, liposomes are spherical vesicles composed of one or more phospholipid bilayers enclosing an aqueous core, enabling the simultaneous delivery of both hydrophilic and lipophilic drugs. This comprehensive review highlights the formulation strategies, characterization techniques, and therapeutic applications of liposomal drug delivery systems. Various methods of liposome preparation, including thin-film hydration, reverse-phase evaporation, ethanol injection, and micro fluidization, are discussed in detail along with factors affecting liposome size, stability, and drug loading efficiency. The review further elaborates on critical characterization parameters such as vesicle size, zeta potential, encapsulation efficiency, in vitro release behaviour, and stability studies. Therapeutic applications of liposomes in cancer therapy, infectious diseases, vaccine delivery, gene therapy, and targeted drug delivery are critically examined, with emphasis on clinically approved liposomal products. Despite their advantages, liposomal systems face challenges related to physical instability, rapid clearance, and large-scale manufacturing. Emerging advancements such as PEGylated liposomes, ligand-targeted liposomes, and stimuli-responsive liposomes are paving the way for next-generation personalized therapeutics. Overall, liposomes continue to represent a versatile and promising platform in modern drug delivery science.