The self-assembly of molecules into large ordered arrays is an efficient and versatile strategy for the formation of functional nanostructures. In particular, incorporating bioactive components into such structures enables them to interact with specific biological targets which could prove useful for both therapeutic and diagnostic medical applications. Peptides — small chains of amino acids — are promising candidates to impart bioactivity to nanostructures because they are known to mediate a range of biological events.

Now, Myongsoo Lee and co-workers1 from Yonsei University in Seoul, Korea have reported a general approach to the formation of self-assembled bioactive nanostructures with good control over their shape and size. A range of molecular building blocks were made in which a hydrophobic lipid chain was grafted to the end of a peptide that is known to penetrate cells. Depending on the size and degree of branching within the lipid, these compounds assemble into either spherical structures (11 nm in diameter) or short cylinders (12 nm in diameter and 100 nm long) that have a hydrophobic lipid core and a hydrophilic peptide shell. Longer cyclindrical nanostructures could be made from building blocks that had branched lipids with modified chain ends.

When cells were incubated with short nanocylinders that had been loaded with red-dye molecules, it was found that the dye was transferred to both the cytoplasm and the nucleus, suggesting that these self-assembled materials are promising candidates for drug-delivery applications.