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The chitosan-g-polyethyleneimine-g-polyethylene glycol graft copolymer was synthesized for delivery of the immunomodulatory agent polyinosinic-polycytidylic acid and the mimetic antigen ovalbumin. The 1H-NMR results showed that polyethylene glycol was successfully grafted onto chitosan-g-polyethyleneimine copolymer by Schiff base reaction in a normal physiological environment (pH 7.4), while polyethylene glycol segments were detached from copolymer in a slightly acidic environment (pH 5.0). The results of cytotoxicity showed that graft copolymer with the modification degree of 47% had very low cytotoxicity, and the cell survival rate was above 95%. Nanoparticles of chitosan-g-polyethyleneimine-g-polyethylene glycol graft copolymer and polyinosinic-polycytidylic acid with different negative/positive charge ratios were obtained by electrostatic self-assembly between graft copolymer, polyinosinic-polycytidylic acid, and ovalbumin. The agarose gel electrophoresis results showed that polyinosinic-polycytidylic acid was well coated by the graft copolymer and protected from nuclease degradation. The performance study of nanoparticles results showed that their particle size with the negative/positive charge ratio of 40 : 1 was about 58 nm, which had the best solution stability, and the encapsulation efficiency of ovalbumin was ~50%, and it also significantly promoted the secretion of TNF-α and IFN-γ. [ABSTRACT FROM AUTHOR]

PolyI:C is an immunomodulatory agent that can be used in immunotherapy, but its transportation in the body is hindered. In this study, a chitosan (CS)- graft -polyethyleneimine (PEI) copolymer (C- g -P) is prepared by an N , N ′-carbonyl diimidazole (CDI) coupling method as a drug carrier for PolyI:C and simulated antigen ovalbumin (OVA). The results of FT-IR, 1H NMR, elemental analysis and cytotoxicity studies show that PEI is successfully grafted onto CS, and a low cytotoxicity of C- g -P- x (x = 1, 2, 3) with different PEI grafting rates are obtained. C- g -P- x -PolyI:C/OVA (C- g -P- x -PO) (x = 1, 2, 3) nanoparticles are prepared by combining C- g -P- x (x = 1, 2, 3), PolyI:C and OVA by electrostatic self-assembly. The results of agarose gel electrophoresis show that PolyI:C is well coated by the graft copolymer and protected from nuclease degradation. The results show that C- g -P-1-PO nanoparticles with graft copolymer to PolyI:C (N/P) ratios of 80:1 have the best solution stability, and the OVA encapsulation efficiency is 60.6%. The nanoparticles also have a suitable size and regular shape to be absorbed by cells. In vitro immunoassay results show that PolyI:C and OVA-loaded nanoparticles promote the secretion of tumor necrosis factor α (TNF-α) and interferon γ (IFN-γ). CS- g -PEI is a reliable drug carrier for the delivery of PolyI:C and OVA, and it also provides the possibility to carry other drugs. A chitosan- graft -polyethyleneimine copolymer (CS- g -PEI) was prepared by an N , N ′-carbonyl diimidazole (CDI) coupling method as a drug carrier for PolyI:C and simulated antigen ovalbumin (OVA). Nanoparticles of CS- g -PEI-PolyI:C/OVA with good solution stability, coating effect, immune characteristics and suitable size were prepared through electrostatic self-assembly. CS- g -PEI protected PolyI:C from nuclease degradation and is a reliable drug carrier for the delivery of PolyI:C. [ABSTRACT FROM AUTHOR]