Dendritic polymer macromolecular carriers for drug delivery

Dendritic polymers are the macromolecular carriers having tree-like three-dimensional structures, which are synthesized following iterative sequence of monomeric conjugation leading to hyperbranched arrangement. The characteristic properties of dendritic macromolecules include monodispersity, multiple surface functionalities, nanometric size, etc., which facilitated these polymers as one of the prominent family of drug delivery carriers or cargos. Along with the traditional synthetic pathways like convergent and divergent, some of the newly developed methods like double exponential growth, hypercores, and branched monomer growth have demonstrated significant productivity in recent years. Dendritic carriers or dendrimers can be categorized into different types on the basis of functionality, biodegradability, and responses toward various stimuli. Some of the well-known classes of dendrimers include poly(amidoamine) (PAMAM), poly(propyleneimine) (PPI), polylysine, poly(ester amide), etc. These drug carriers offer several advantages such as solubility enhancement of hydrophobic drugs, targeted delivery through surface engineering, etc. However the cationic charge associated with dendritic polymers usually poses challenge of in vitro as well as in vivo toxicity. Therapeutic moieties may be delivered to the targeted site through dendritic polymer macromolecular carriers using certain basic approaches, namely encapsulation, conjugation, and electrostatic interactions. Cytotoxicity, hematological toxicity, immunogenicity, and in vivo toxicity put questions over their effectiveness and therefore sometimes these are considered as the dark wave of these carriers. Dendrimers have been utilized successfully to deliver anticancer agents, antimicrobials, gene, etc., via excellent host-guest chemistry. This chapter is focused on the concepts, design, and therapeutic applications of dendritic polymer macromolecular carriers. It includes discussion of key basic properties, synthesis of the concerned macromolecules, their types, associated toxicity, and possible drug delivery approaches. Last part of the chapter is dedicated to the applications of dendritic polymers in the delivery of therapeutic agents for the effective management of various diseases.