Figure 2.

Liposomal delivery vehicles. Liposomes are spherical drug delivery vehicles made of a phospholipid bilayer with an aqueous core. Its hydrophobic and hydrophilic nature accommodates hydrophobic cargo in between the lipid layers and hydrophilic cargo in the aqueous compartment or conjugated to the external lipid polar headgroups. The polyethylene glycol (PEG) coating of liposomes prolongs their circulation by reducing uptake by macrophages. Surface labeling with antibodies promotes liposomal targeting to specific cells and cellular uptake. Cholesterol in the hydrophobic domain of the bilayers affects liposomal rigidity and permeability.