Hybrid polymer-colloid systems as MRI-detectable nanocarriers for vaccine delivery

Various types of PHPMA polymers (semitelechelic homopolymers, statistical copolymers and di-block copolymer) were attached to the surface of γ-Fe₂O₃ particles via an iron-chelating deferoxamine group linked to the ends of their chains through stable or stimuliresponsive bonds. The resulting materials were stable, well-defined nanoparticles characterized by negligible toxicity and suitable hydrodynamic size and shape for efficient uptake by immune cells; those having polymers attached via stimuliresponsive bonds exhibited rapid decoating upon being incubated in the solutions mimicking reductive environment inside the cells. In addition, the favorable magnetic properties of the nanoparticles enabled their detection by MRI, which can be used to monitor their pharmacokinetics. Finally, a minimal peptide immunogen derived from the HIV-1 binding site (V3) was successfully conjugated to exemplary polymer-colloid systems to demonstrate their suitability for vaccine delivery. (authors)