The dry powder formulation of mixed cross-linked dextran microspheres and tetanus toxoid-loaded trimethyl chitosan nanospheres as a potent adjuvant for nasal delivery system

Objective(s): The present study aimed to determine the immunoadjuvant efficacy of mixed cross-linked dextran microspheres (CDM) and tetanus toxoid (TT)-loaded trimethyl chitosan (TMC) nanospheres in dry powder form. Materials and Methods: The TMC nanoparticles (NPs) containing TT were produced using the ionic gelation method. Co-administration of TT-loaded TMC NPs and CDM as an absorption enhancer was performed to improve immunity against the antigen. Dry powder formulations were delivered via the nasal route in a rabbit model. Results: Among immunization groups, mixing of CDM with TT encapsulated in TMC NPs could elicit the highest titer of systemic IgG antibody. Furthermore, the addition of CDM to TT-loaded TMC enhanced the sIgA response relative to the TT solution. Conclusion: The TMC NPs had a considerable effect on mucosal and systemic immunity against the TT antigen. Therefore, the CDM excipient can be utilized for nasal immunization to elevate systemic and mucosal responses.

Automated summary

The study found that the combination of CDM and TMC nanospheres can enhance the immune response to the TT antigen. In a rabbit model, this combination resulted in the highest titer of systemic IgG antibodies and also boosted mucosal immune responses.