Synthesis and physicochemical properties of lipophilic polyamide dendrimers

To synthesise symmetrical dendritic macromolecules with external lipid surfaces, to investigate their behaviour at the air-water interface and their ability to form supramolecular aggregates, and to gain an understanding of their potential as drug carriers.

Dendrimeric compounds were synthesised with molecular weights ranging from 737 (1st generation dendrimer) to 25,246 (6th generation dendrimer) with carbon numbers ranging from 40 to 1404. The surface behaviour of these compounds was determined using spread films at the air/water interface on a Langmuir trough, and transmission electron microscopy was used to study the supramolecular aggregates formed by the more hydrophobic members of the series.

Dendrimers up to a maximum of 6 generations were synthesised. Surface saturation did not allow the completion of the synthesis of the 7th generation. The limiting surface areas at the air/water interface ranged from 0.4 nm2 to 16.1 nm2 values in good agreement with the areas derived from computer generated molecular models (0.5 nm2 to 14 nm2).

The synthesised dendrimers exhibited a linear relationship between area per molecule and the molecular weight of the compounds. A dendrimer with 16 lipoamino acid branches formed tubular supramolecular aggregates with a helical structure and dimensions in the long axis of 140-200 nm.