dendrimer

Dendrimers are a class of synthetic macromolecules characterized by a central core from which repeatedly branched units radiate outward in a tree-like, highly symmetrical architecture. They are typically monodisperse, with well-defined molecular weight and shape, in contrast to conventional polymers. Dendrimers are built by iterative chemical steps in two main routes: divergent synthesis, where growth proceeds from the core toward the periphery, and convergent synthesis, in which dendritic fragments are assembled and then joined to a core. Each growth cycle adds a generation, increasing both size and the number of terminal functional groups.

Common dendrimer families include polyamidoamine (PAMAM) and polypropyleneimine (PPI) dendrimers. Their surfaces bear functional groups such as amines, carboxyls, or hydroxyls, enabling solubility tuning and multivalent interactions. The internal structure contains cavities capable of encapsulating guest molecules, while the abundant surface groups allow high levels of functionalization for targeting, binding, or catalysis.

Applications span medicine, materials science, and catalysis. In drug delivery, dendrimers can improve solubility, pharmacokinetics, and targeting, and can enable controlled release. They are explored for gene delivery with cationic surfaces, and as imaging or contrast agents in diagnostic techniques. Dendrimers also serve as catalysts or nanoreactors and as components in sensing and nanomaterials.

Challenges include the labor-intensive and costly synthesis at scale, purification requirements, and concerns about toxicity or biocompatibility related to surface charge. Ongoing research aims to enhance biodegradability, safety, and cost-effectiveness. The term dendrimer was coined in the 1980s to describe these highly branched macromolecules.