Highly convergent synthesis of dendrimerized chitosan-sialic acid hybrid

Surface bound chitosan-sialodendrimers with a high degree of substitution were successfully prepared using a doubly convergent approach. Poly(amidoamine) (PAMAM) dendrimers (G = 1-5) having a 1,4-diaminobutane core were amidated to N-carboxyethylchitosan methyl ester under conditions that prevented cross-linking. The extent of attachment (DS) to the polysaccharide backbone decreased from 0.53 to 0.11 with increasing dendrimer generation. Peracetylated p-formylphenyl alpha -sialoside was then successfully attached to the primary amine end groups of the dendrimerized chitosan hybrid with degree of substitution (DS) ranging from 0.7 to 1.4 using reductive amination. Water-soluble chitosan-sialodendrimer hybrids were finally obtained after protecting group hydrolysis and chitosan N-succinylation.