7.2.2.2　Polymer microcapsules

Polymer microcapsules have a core-shell structure，which provides a multiphase storage space for the storage and delivery of highly loaded hydrophilic and hydrophobic drugs.The hydrophilic domain can be used to store antibodies，cytokines and other proteins in the active state，overcoming the instability or inactivation caused by unavoidable exposure to organic solvents during drug coating.Moreover，the microcapsules made of polyelectrolyte layer can improve the antigen delivery and enhance the immune response compared with the homogeneous microspheres prepared by similar materials.For example，Andry et al.reported that degradable hydroxyethyl starch（HES）microcapsules with sizes of 4-15μm，which loaded with bovine serum albumin for the melanoma immunotherapy to enhance the antigen presentation effect.Otherwise，Ma et al.constructed a Pickering emulsion with a particle size of about 10 μm by assembling spherical nanoparticles around the oil-water interface of the squalene emulsion as a common vaccination strategy.The Pickering emulsion retains the force-dependent deformability and lateral mobility of the presented antigen，resulted in adjustable phagocytosis and in vivo distribution as well as high biosecurity and antigen-loading capacity.The core，shell，and surface of the Pickering emulsion provide various effective loading sites for antigens，adjuvants and other immunomodulators，which are then presented to APCs to enhance the durability and effectiveness of the melanoma vaccine.(https://www.daowen.com)