Toll-like receptor-2 agonist functionalized biopolymer for mucosal vaccination

The objective of this study was to provide a new water-soluble chitosan derivative being functionalized with a Toll-like receptor-2 (TLR-2) agonist. At first, we synthesized the water-soluble TLR-2 agonist ω-amido-[Nα-palmitoyl-oxy-S-[2,3-bis(palmitoyl-oxy)-(2R)-propyl]-[R]–cysteinyl]-α-amino poly(ethylene glycol) (Pam3Cys-PEG-NH2), which was characterized by 1H and 13C NMR as well as mass spectroscopy. Secondly, Pam3Cys-PEG-NH2 was then successfully grafted to 6-O-carboxymethyl-N,N,N-trimethyl chitosan polymers (CM-TMC) using EDC/NHS as condensing agents. The copolymer was analysed by means of 1H and 13C NMR and FTIR spectroscopy. 13C NMR spectroscopy did not deliver evidence that an amide bond was formed between CM-TMC and Pam3Cys-PEG-NH2. However, 1H NMR and FTIR spectroscopy demonstrated clearly that successful grafting took place. Based upon these results, this new TLR-2 functionalized biopolymer merits further investigations as material for vaccine delivery systems.