7.2.2　Polymer micromaterials

Polymer micromaterials（generally larger than 1 μm in size）can interact with a single cell，which play an important role in tumor immunotherapy.Moreover，polymer micromaterials with selectivity and tunability can activate and expand the immune cell population，improve drug（e.g.，antibodies，cytokines）delivery compared with polymer nanomaterials，and adjust their phagocytosis and distribution in vivo for its easy to deformation.The applications of polymer micromaterials in tumor immunotherapy are mainly reflected in two aspects.One is that as artificial antigen presenting cells（aAPCs），they are used to induce and amplify T cell populations.The other is that they enhance the immunotherapy of melanoma as immunotherapeutic drug carriers，such as antibodies，cytokines and antigens.Polymer micromaterials are expected to overcome the challenges of polymer nanomaterials in tumor immunotherapy，such as tissue homing and circulation in vivo.Polymer micromaterials used in melanoma immunotherapy mainly include PLGA，PLGA hybrid materials，PLA and polystyrene.There are mainly polymer microspheres and polymer microcapsules in morphology.(https://www.daowen.com)