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Self‐assembled polymeric nanoparticle (NP) drug carriers are capable of encapsulated and controlled delivery, facilitating improvements in the therapeutic efficiency of drugs. Here we report a series of poly(l‐glutamic acid)‐g‐methoxy poly(ethylene glycol)/4‐phenylbutyl ester (PLG‐g‐mPEG/PB) copolymers, which were synthesized by esterification of 4‐phenylbutanol (PB) and PLG‐g‐mPEG in different feed ratios. The copolymers obtained form into nano‐sized micelles in aqueous solution by a self‐assembly process, with lower critical micelle concentration value for higher PB ratio in the copolymers. Variable temperature infrared spectroscopy and circular dichroism were used to prove the breaking of intermolecular hydrogen bonds after PB modification. Podophyllotoxin (PPT), an effective anticancer agent, was incorporated into the inner core of the micelle system by physical entrapment through hydrophobic interaction between the drug and the PB‐modified copolymers. Both the drug loading content and the loading efficiency increased with PB content in the PLG‐g‐mPEG/PB copolymers and reached an ultrahigh value of 28.2 wt% and 94%, respectively. The PPT‐encapsulated micelles (PPT‐NPs) were stable at pH 7.4 but dissociated and released 80% of loaded PPT in a weak acidic environment (pH 5.0). The in vitro proliferation of non‐small‐cell lung cancer cells (A549) was significantly inhibited by PPT‐NPs in a cytotoxicity assay. These results demonstrate that hydrophobic modification is an efficient route for tuning the self‐assembly behaviour and drug encapsulation of PLG‐g‐mPEG copolymers, and our PLG‐g‐mPEG/PB will serve as a promising carrier for hydrophobic anticancer drug delivery. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Abstract: For most cancer types, only a minority of cancer patients respond to checkpoint inhibition therapy. T lymphocyte infiltration is critically important for checkpoint blockade immunotherapy. High expression of high mobility group protein A1 (HMGA1) is observed in rapidly proliferating neoplastic cells, and is reported to contribute to the immunosuppressive microenvironment in the tumor. Herein, whether the silencing of HMGA1 using a nanoparticle (NP) approach could promote T lymphocyte infiltration into the tumor, and sensitize tumors to checkpoint inhibitor therapy in several orthotopic murine cancer models, which has high levels of HMGA1 but little T lymphocyte infiltration, is investigated. Selectively silencing HMGA1 using a lipid‐protamine‐hyaluronic acid‐siHMGA1 (LPH‐siHMGA1) NP system greatly enhances the lymphocyte infiltration in the tumor. Furthermore, the combination of LPH‐siHMGA1 and a locally expressed PD‐L1 inhibitor system, a lipid‐protamine‐DNA NP loaded with plasmid encoding the PD‐L1 trap fusion protein, significantly inhibits the tumor growth and prolonged survival. LPH‐siHMGA1 also decreased the content of stem cells in the tumor. These findings highlight the potential of targeting HMGA1, especially using a nano approach, in the combination with cancer immunotherapy, and provide a strategy for broadening the application and enhancing the efficacy of checkpoint inhibitors. [ABSTRACT FROM AUTHOR]

Immunotherapy has emerged as an effective strategy for the prevention and treatment of a variety of diseases, including cancer, infectious diseases, inflammatory diseases, and autoimmune diseases. Immunomodulatory nanosystems can readily improve the therapeutic effects and simultaneously overcome many obstacles facing the treatment method, such as inadequate immune stimulation, off‐target side effects, and bioactivity loss of immune agents during circulation. In recent years, researchers have continuously developed nanomaterials with new structures, properties, and functions. This Review provides the most recent advances of nanotechnology for immunostimulation and immunosuppression. In cancer immunotherapy, nanosystems play an essential role in immune cell activation and tumor microenvironment modulation, as well as combination with other antitumor approaches. In infectious diseases, many encouraging outcomes from using nanomaterial vaccines against viral and bacterial infections have been reported. In addition, nanoparticles also potentiate the effects of immunosuppressive immune cells for the treatment of inflammatory and autoimmune diseases. Finally, the challenges and prospects of applying nanotechnology to modulate immunotherapy are discussed. [ABSTRACT FROM AUTHOR]