Dendrimern

Dendrimern, commonly referred to as dendrimers, are synthetic macromolecules with a highly branched, tree-like architecture built from a central core and successive layers of branching units, called generations. They are defined by a well-defined, monodisperse size and a multivalent surface rich in functional end groups.

Structure and synthesis: A dendrimer consists of a central core, interior branching units (dendrons), and a terminal shell. With each generation, the number of terminal groups increases, while the interior becomes densely packed. The surface can be tailored by choosing end-group chemistry, enabling solubility control and functionalization.

Dendrimers are typically prepared by iterative, divergent or convergent growth. In divergent synthesis, growth proceeds outward from the core; in convergent synthesis, dendritic fragments are assembled separately and then joined to a core. Accelerated approaches and improved purification have enabled higher generation dendrimers, though synthesis can become challenging due to steric hindrance and cost.

Properties and applications: Dendrimers are nanometer-scale molecules with narrow molecular weight distributions and precise architecture. Their multiple, uniformly distributed end groups allow high surface functionality, making them useful for drug delivery, gene therapy, and imaging. They also find use as catalysts, coatings, and nanoreactors. The biocompatibility and toxicity of dendrimers depend on core and surface chemistry.

History: The dendrimer concept emerged in the 1980s through the work of Donald Tomalia, Jean Frechet, and colleagues. The term dendrimer reflects the tree-like, dendritic structure. Since then, dendrimers have been studied extensively, with many variants like PAMAM and PPI.