Figure 3.

(A) Liposomes are phospholipid and cholesterol self-assembled bilayer membranes that enclose an aqueous core, where hydrophilic molecules can be incorporated. Hydrophobic compounds can also be incorporated in the lipid bilayer. Liposomes can be classified in (i) small unilamellar vesicles (SUVs); (ii) large unilamellar vesicles (LUVs) and (iii) multilamellar vesicles (MLVs), according to their size and lamellarity. (B) Polymeric nanoparticles are submicron spherical entities composed by a polymeric compact net than can either constitute a polymeric matrix—in the case of nanospheres—or a polymeric wall surrounding a vesicular core—nanocapsules. Nanoparticles can transport hydrophilic and hydrophobic molecules either entrapped in the polymeric matrix or core, or adsorbed to their surface. (C) Polymeric micelles are self-assembled spherical nanocarriers formed by amphiphilic block copolymers. In aqueous medium, the block copolymers arrange themselves in a disposition where the most hydrophobic parts of their chains form a hydrophobic core—where hydrophobic molecules can be incorporated –, and the most hydrophilic regions of the polymer chain are displayed outoward. (D) Dendrimers are hyperbranched nanocarriers formed by a central core, branching monomers and functionalized peripheral groups. Dendrimer synthesis can start from the core element (divergent polymerization) or from the peripheral branching units (convergent polymerization), resulting in a structure with a hydrophilic surface and a hydrophobic central core. Molecules can be transported by dendrimers either incorporated in the core and branches, either conjugated to the terminal groups.