The global spread of SARS-CoV-2 can only be contained through vaccine development. Vector vaccines (DNA and viral) can be produced rapidly and inexpensively with current synthesis technologies. Challenges with DNA vaccines include degradation by DNases, inefficient uptake by antigen-presenting cells, and low immunogenicity. The Quil-A-loaded chitosan particulate adjuvant system (QAC) enables transport of plasmid DNA directly to target cells and delayed release over time. Here, we present two recent studies about chitosan-based delivery systems for vaccines.

Chitosan and chitosan derivatives are promising biopolymers for nasal or vaginal drug delivery using micro- or nanoparticles. However, the pH-dependent solubility of chitosan and excessive water uptake in the presence of ions is suboptimal. Water uptake can result in rapid initial release of the drug due to collapse of the chitosan-based transport vehicle. To stabilize the drug release, research is being conducted to modify the polymer structure by physical crosslinking. Aim of the presented study was to investigate the influence of microparticle composition, in particular the amount of ion crosslinker (CF) introduced, on the release profile of water-soluble drugs from the chitosan matrix.