Multifunctional dendritic drug delivery systems: Design, synthesis, controlled and triggered release

This review describes the strategy for the development of multifunctional dendrimeric and hyperbranched polymers, collectively named dendritic polymers, aiming at their application as drug and gene delivery systems. Employing well-characterized and mainly commercially available dendritic polymers, the functionalization of these polymers is aimed at providing drug carriers of low toxicity, high encapsulating capacity, specificity to certain type of cells and transport ability through their membranes. Following a step-wise functionalization strategy of the starting dendritic polymers one has the option to prepare products that fulfill one or more of these requirements. In particular, in addition to polyvalency which is a common feature of the dendritic polymers, these carriers bearing a number of targeting ligands exhibit specificity to certain cells, another type of groups secures stability in biological milieu and prolonged circulation, while other moieties facilitate their transport through cell membranes. Furthermore, dendritic polymers applied for gene delivery should be or become cationic in the biological environment for the formation of complexes with the negatively charged genetic material.