Liposomes in the intersection of innovation: Basic structures and preparation technologies to the recent advancements in therapies and future perspectives

Liposomes have become one of the most widely and clinically important nanocarrier systems of the new drug delivery. Their distinct structural characteristics, in the form of phospholipid bi-layers that are able to encapsulate both hydrophilic and hydrophobic drugs, facilitate increased therapeutic efficacy, lesser systemic toxicity and enhanced compliance in the patients. The basic principles of liposomal drug delivery, namely physicochemical determinants, lipid composition, particle size, surface charge, and stability factors are pointed out in this review. It also discusses how liposomes can be classified as conventional, stealth, targeted and stimuli-responsive systems. The traditional and advanced techniques of preparation (thin-film hydration, reverse phase evaporation, sonication, ethanol injection, dual centrifugation and supercritical fluid-assisted) are given, their pros and cons, and the possibility of scaling to large scale are highlighted. Applications in clinical fields especially oncology, infectious diseases, and biotechnology are discussed as well as emerging applications in the food and cosmetic industries. Taken together, this review highlights the critical importance of liposomes as flexible nanocarriers and suggests future developments which can address the current limitations to increase their translational effectiveness.