7.2.1.2　Nanogels

Nanogels are the main carrier materials for melanoma immunotherapy.Nanogels are made from natural polymers（e.g.，polysaccharides，peptides and nucleic acids），synthetic polymers（e.g.，poly（ethylene glycol）and PNIPAM）and their combinations.Compared with solid NPs，nanogels possess characteristically soft，which can improve the circulation and biological distribution of NPs in vivo and have the effect of immunoadjuvant.Ma et al.synthesized an amphiphilic pH-sensitive galactosyl dextran-retinal nanogel loaded OVA antigen to construct a self-adjuvant tumor vaccine to promote DCs maturation，antigen uptake and cytoplasmic antigen release，which further augmenting MHC-Ⅰ antigen presentation and eliciting potent anti-melanoma immune response.Nostrum et al.constructed a tumor vaccine by using cationic dextran nanogel as carrier conjugated model antigen OVA via disulfide bonds.The vaccine combined with immunoadjuvant poly（I：C）can produce a strong anti-tumor immune response in tumor prevention model and treatment model，which can effectively inhibit tumor genesis and development.Wang et al.demonstrated an enzyme-responsive polypeptide-crosslinked nanogel by using polypeptides as chemical crosslinking agents and N-isopropyl acrylamide（NIPAAM）as scaffold by precipitation polymerization.The nanogel can encapsulate the tumor metastasis inhibitor peptide P-5m with high loading capacity，thereby showing significant inhibitory effect on metastatic melanoma.(https://www.daowen.com)