LAUSR

Four kinds of A3B-type amphiphilic polydepsipeptides, (poly(sarcosine))3-b-poly(l-lactic acid) (the degree of polymerization of poly(sarcosine) are 10, 33, 55, and 85; S103, S333, S553, and S853) were synthesized to prepare core-shell type polymeric micelles. Their in vivo dispositions and stimulations to trigger immune system to produce IgM upon multiple administrations to mice were examined. With increasing poly(sarcosine) chain lengths, the hydrophilic shell became thicker and the surface density at the most outer surface decreased on the basis of dynamic and static light scattering measurements. These two physical elements of polymeric micelles elicited opposite effects on the immune response in light of the chain length therefore to show an optimized poly(sarcosine) chain length existing between 33mer and 55mer to suppress the accelerated blood clearance phenomenon associated with polymeric micelles.