dendrimers

Dendrimers are synthetic macromolecules with a highly branched, tree-like architecture emanating from a central core. They are nanometer-scale and highly uniform, with a core, successive generations of branching units, and a peripheral layer of terminal groups. The interior contains cavities that can encapsulate guest molecules, while the surface provides abundant sites for chemical modification.

Synthesis proceeds generation by generation, using divergent growth from the core or convergent assembly of peripheral fragments. Well-known families include PAMAM (poly(amidoamine)) and PPI (poly(propylene imine)) dendrimers, differing in core and branching chemistry. Generations are designated G0, G1, G2, and so on, increasing in size and surface functionality.

Key properties include high monodispersity, defined molecular weight, and tunable solubility and surface chemistry. The dense peripheral groups enable conjugation with drugs, imaging agents, or targeting ligands, while internal voids allow encapsulation or host-guest interactions. The choice of core, branching units, and surface groups governs biocompatibility, toxicity, and pharmacokinetics.

Applications span drug and gene delivery, catalysis, sensing, and diagnostic imaging. In medicine, dendrimers can act as carriers for therapeutics, with surface modification reducing toxicity and improving targeting. Limitations include synthetic complexity and cost at higher generations, as well as potential toxicity depending on chemistry. Dendrimers were first reported in the 1980s by Tomalia, Frechet, and Hawker, who coined the term and demonstrated the utility of highly branched macromolecules.