Chitosan, N,N,N-trimethyl chitosan (TMC) and 2-hydroxypropyltrimethyl ammonium chloride chitosan (HTCC): The potential immune adjuvants and nano carriers.

Vaccine is an important means to prevent diseases, which have attracted the attention of many researchers. However, the immune efficacy of vaccine is limited and requires effective antigen delivery and adjuvant systems to provide appropriate vaccines or immunotherapy antigens for improving the immune efficacy of the mucosal immune system. Recent years, the application of chitosan and its derivatives in immunization have attracted a lot of attention. Many research results proved that chitosan and its derivatives were promising vaccine adjuvants and carriers, which improved immune response for its promising mucoadhesive properties. Among the derivatives, TMC and HTCC are currently the most studied quaternized chitosans. In the first part of our review, we elucidate the preparation methods of chitosan, TMC and HTCC and the factors that may affect their immunity. In the second part, not only we introduce their application as adjuvants and carriers to improve the efficacy of vaccines, but also their application as surface modification materials to improve immune response. All in all, we hold that chitosan, TMC and HTCC are promising biomaterials that can be used to improve immune efficacy, of which TMC may have good development potential.