Synthesis of spacer-armed glucodendrimers based on the modification of poly(propylene imine) dendrimers

The use of preformed poly(propylene imine) dendrimers [DAB(Pa)x] with reactive primary amine end groups proved to be very useful for the construction of saccharide surface-coated dendrimers. For this purpose, amide bonds were introduced by a reaction between the primary amine end groups of the dendrimers with N-succinimidyl-activated esters of spacer-armed acetyl-protected thioglucopyranoside units. The linear alkyl chain spacers between the dendrimer surface and the saccharide units was increased in length with 1, 5 and 10 carbon atoms. These spacer arms were introduced to determine the influence of local saccharide surface concentration variations on the dendrimer properties. After modification of the dendrimers with these saccharide units, the acetyl protecting groups were removed. Purification of these derivatives was accomplished by using dialysis either in water or in aqueous methanol. The solubility behavior of the resulting glucodendrimers proved to be strongly dependent on the hydrophobic part, i.e. the alkyl chain spacers in the molecule. Therefore, these nanosized multivalent structures, appropriate for studying carbohydrate-protein interactions, are also proposed useful for investigating amphiphilic properties.