Self-assembly of some amphipathic dendrons

Characterisation of a range of new amphipathic dendrons with varying dendritic lysine head groups containing terminal amino groups and hydrophobic tails with 1-3 adjacent (C-10 to C-18) alkyl chains has included exploration of their ability to self-associate in aqueous media. Field flow fractionation was the main technique employed. Comparisons were made with the non-lipidic dendrons in the series, which do not self-assemble. Amphipathic dendron with three C-14 chains and eight terminal NH2 groups formed aggregates with a molecular weight of 52,700 Da (aggregation number 33). The C-18 analogue had an aggregation number of 78 and a molecular weight of 138,000 Da. Estimated radii of gyration were about 20 and 32 nm, respectively. Transmission electron micrographs demonstrate a uniformity of size of about 50 nm in diameter and some internal structure of aggregates in the presence of 0.1% NaCl. Estimates of the free energy of lipidic dendron association were made and the relationship between the number of methylene groups in the hydrophobic tails and the aggregation number established.