Deprotection-Induced Morphology Transition and Immunoactivation of Glycovesicles: A Strategy of Smart Delivery...

We proposed the deprotection-induced block copolymer self-assembly (DISA); that is, the deprotection of hydroxyl groups resulted in in situ self-assembly of glycopolymers. In the previous studies, block copolymers soluble in common organic solvents were employed as the starting material. In this paper, by using the protected glyco-block containing preassembled glycovesicles in water as the starting material, we moved forward and made two exceeding achievements. First, we have observed a deprotection-induced morphology transition triggered by alkali in water. The carbohydrate-carbohydrate interactions were considered to contribute to such a morphology transition during deprotection. Second, lipase was found to be an efficient enzymatic trigger in the sugar deprotection, which motivates the immune-application of this morphology transition process. When lipase and a model antigen, ovalbumin (OVA), were encapsulated inside the glycovesicles, the deprotection of sugars by lipase induced the transition of vesicles to micelles and the lipase and OVA were released accordingly. When glycovesicles were internalized by dentritic cells (DCs), the lipase from lysosomes efficiently induced the release of OVA and presentation of antigen to T cells. During the process, lysosomal lipase performed as a trigger on the deprotection of sugars and the release of protein without any other reagents. The significance of this design is that as a delivery vehicle, the protected glycovesicles not only avoided unnecessary immune activation but also worked with the released OVA together; that is, the glycovehicle successfully activated DCs and improved the presentation efficiency of T cells remarkably.