The relationship between the structure of the headgroup of sphingolipids and their ability to form complex high axial ratio microstructures.

Ceramides with chemically modified polar headgroups were prepared and examined for their ability to form complex high axial ratio microstructures (CHARMS), potential drug delivery vehicles. In general, if the modified ceramide had either a hydrogen bond donor or acceptor at C-1 and C-3, including hydrophobic or hydrophilic groups attached to C-1 microstructures formed. Tolerated groups include amides, esters, sulfonates, and ethers. If modification at C-3 added significant bulk (greater than four carbons regardless of hydrophilicity), then amorphous aggregates formed. Ceramides with C-1 and C-3 bridged through a cyclic structure also made microstructures. By using a sphingolipid with an amine headgroup, CHARMs may be modified covalently after formation.