Designing Next Generation Polyanhydride Copolymers for Nanoparticle-Based Vaccines

Polyanhydride nanoparticle-based vaccines (i.e. nanovaccines) offer many benefits over traditional vaccines, such as possessing controllable release profiles, surface erosion kinetics, vaccine dose-sparing capacity, chemistry-dependent immunomodulation, and protein shelf-life stability. These nanovaccines are comprised of copolymers of 1,6-bis(p-carboxyphenoxy) hexane (CPH), 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG), and sebacic acid (SA), with each of these monomers offering its own beneficial properties. In particular, nanoparticles that are high in CPTEG content have been shown to improve cellular internalization and persistence as well as facilitate the retention of encapsulated protein secondary and tertiary structure. Nanoparticles high in SA content have demonstrated improved cell internalization and shelf-life stability of encapsulated proteins. Therefore, CPTEG:SA copolymers have been synthesized to maximize the properties of each individual component. These new copolymer chemistries were characterized for molecular composition and molecular weight via nuclear magnetic resonance spectroscopy (NMR) and glass transition temperature and melting point via differential scanning calorimetry (DSC). As expected, several of the CPTEG:SA copolymers have glass transition temperatures greater than body temperature and therefore could be useful for vaccination applications in the future. Flash nanoprecipitation was utilized to form nanoparticles from these novel chemistries which were examined by scanning electron microscopy (SEM) which showed very discrete particulate structures. Cellular uptake was investigated through flow cytometry which provided significant evidence that CPTEG:SA nanoparticles are readily taken up by J774 macrophages providing evidence of their potential viability as nanovaccines.