Recent progress in dendrimer-based nanocarriers

A large number of drug delivery systems-mostly in the form of liposomes, microspheres, nanoparticles and hydrogels-have been designed to achieve targeted delivery and sustained release of drugs by exploiting the inherent properties of polymers. The size, shape, and surface properties of the polymer are used to modulate the pharmacokinetic and pharmacodynamic behavior of drugs conjugated with or encapsulated in the polymeric carrier. Recently, a class of well-defined, monodisperse, and tree-like polymers called dendrimers has attracted attention because of the flexibility they offer in terms of their size, shape, branching, length, and surface functionality. A unique characteristic of dendrimers is that they can act as a particulate system while retaining the properties of a polymer. Drugs and diagnostic agents can be encapsulated in the central core or bound to the surface of the dendrimer by noncovalent or covalent interaction. Dendritic polymers can significantly improve pharmacokinetic and pharmacodynamic properties of low molecular weight and protein-based therapeutic agents. Furthermore, fluorescent antibodies and imaging contrast agents can be bound to these new polymers and the resulting complexes can be used for analyzing biological fluids and for diagnosis. Because of their size, shape, and ability to conjugate with a wide range of chemical entities, dendrimers have found many applications in the pharmaceutical and biomedical sciences. This review focuses on the unique carrier properties of biomimetic dendrimers and discusses a wide range of applications of dendrimers in drug delivery, including their use as drug solubilizers, absorption enhancers, release modifiers, and carriers for targeting drugs and diagnostic agents.