Nasal immunisation with nanoparticles has already shown promising results. In this study, nanoparticle composites carrying BSA for nasal vaccination prepared using electrostatic interaction process between polycation N-trimethyl chitosan chloride (TMC), chitosan glutamate (CG), chitosan chloride (CCl) and polyanion carboxymethyl pullulan (CMP). A mass ratio of 2:1 for TMC-CMP combination produced stable nanocarriers. For CCl-CMP and CG-CMP formulations needed a mass ratio of 3:1. Loading efficiency was >90% for all formulations. Nanoparticles' size ranged from 207 to 603 nm. The surface charge of the complexes varied between +14 and +33 mV. SDS-PAGE integrity of the model antigen was also demonstrated. MTT studies showed that nanoparticle composites were less toxic to Calu-3 cells than the particles of cationic polymers alone. FITC-BSA loaded nanoparticles efficiently taken up by J774A.1 macrophages as confirmed by confocal microscopy highlighting the potential of these novel nanoparticulate carriers' use for nasal vaccination.

Here, we aimed at developing chitosan/pullulan composite nanoparticles and testing their potential as novel systems for the nasal delivery of diphtheria toxoid (DT). All the chitosan derivatives [N-trimethyl (TMC), chloride and glutamate] and carboxymethyl pullulan (CMP) were synthesised and antigen-loaded composites were prepared by polyion complexation of chitosan and pullulan derivatives (particle size: 239-405 nm; surface charge: +18 and +27 mV). Their immunological effects after intranasal administration to mice were compared to intramuscular route. Composite nanoparticles induced higher levels of IgG responses than particles formed with chitosan derivative and antigen. Nasally administered TMC-pullulan composites showed higher DT serum IgG titre when compared with the other composites. Co-encapsulation of CpG ODN within TMC-CMP-DT nanoparticles resulted in a balanced Th1/Th2 response. TMC/pullulan composite nanoparticles also induced highest cytokine levels compared to those of chitosan salts. These findings demonstrated that TMC-CMP-DT composite nanoparticles are promising delivery system for nasal vaccination.