Insights on Natural Membrane Characterization for the Rational Design of Biomimetic Drug Delivery Systems

Cell membranes are vital for living organisms and serve as a dynamic barrier between the internal and external environments. They are composed of a complex lipid bilayer embedded with proteins, allowing them to perform multiple functions like maintaining the cell structure, regulating which substances enter or leave the cell, and intercellular communication. Cellular functions are inherently linked to their membrane properties, and the heterogeneous nature of cell membranes makes the study of their physico-chemical properties extremely challenging. This review is intended to provide a comprehensive overview of the composition and physical features of the cell membrane, by focusing on the lipid and protein composition, and on the physical properties (like membrane stiffness or fluidity), highlighting how these characteristics influence cell functions. An insight into the similarities and differences from the membranes of extracellular vesicles (naturally secreted by almost all cell types) is also provided. The understanding of the physico-chemical properties of cell membranes might find application in different therapeutic fields, like disease diagnosis and development of novel drug delivery systems. Therefore, an overview of the literature works describing the rational design of biomimetic drug delivery systems is presented, focusing on the choice of lipid components, frequently inspired by the study of the composition of naturally secreted exosomes, and on the physical characterization of the systems. In the future, in-depth study of biologic vesicles might lead to the development of promising formulation for drug delivery, possibly enhancing the therapeutic outcomes of many pathologies, like cancer.