On-Demand Nanovaccines Manufacturing

Our laboratory has developed technologies for the production of polymer nanocapsules consisting of different combinations of oils and polymers, notable chitosan [1], hyaluronic acid [2], and polyglutamic acid [3]. These nanocapsules have been generally produced by the solvent displacement technique, which so far has allowed us the formation of nanocapsules with a size in the range of 100-300 nm.

With this work we aimed to achieve a double goal: from a technological perspective, our objective has been to identify the critical parameters that influence the size and the polymer deposition (one or multiple polymer layers) around the oily droplets; and, in that way, to obtain nanocapsules of well defined sizes and with different surface structures. Besides, from a biomedical point of view, the goal was to study the potential of selected nanocapsules as nanocarriers for vaccines antigens.

Two achieve these two goals, NCs of chitosan/lecithin/vitamin E have been used as a model system. The ratio between organic and aqueous phase, as well as the pressure of the addition of the first one over the second one, have shown to be the most critical parameters that affect the final size of nanocapsules (from 50 nm up to 500 nm). Moreover, nanocapsules with different layers of oppositely charged polymers in the shell could be easily prepared by ionic interactions. With this mild method we built up to 5 layers of chitosan-dextran sulfate surrounding the lecithin/vitamin E core.

Finally, to show the potential of these nanosystems as carriers for vaccination, a model antigen from E. coli was associated to the first layer of both, the monolayer and the bilayer nanocapsules. The association efficiency was high in both cases (67% and 71%). The second layer of dextran sulfate makes the formulation more stable after freeze-drying and retards the release of the antigen. In vitro studies in macrophages have shown moderate toxicity, good cell internalization and the production of cytokines related with the activation of the macrophages. With all these data we envisage that both monolayer and bilayer nanocapsules are promising candidates to test in vivoas thermostable vaccines.

[1] S. Vicente, B. Diaz-Freitas, M. Peleteiro, A. Sanchez, D.W. Pascual, A. Gonzalez-Fernandez, et al., A Polymer/Oil Based Nanovaccine as a Single-Dose Immunization Approach, PLoS One. 8 (2013) 2–9. doi:10.1371/journal.pone.0062500.

[2] F.A. Oyarzun-Ampuero, G.R. Rivera-Rodriguez, M.J. Alonso, D. Torres, Hyaluronan nanocapsules as a new vehicle for intracellular drug delivery, Eur. J. Pharm. Sci. 49 (2013) 483–490. doi:10.1016/j.ejps.2013.05.008.

[3] E. Borrajo, R. Abellan-Pose, A. Soto, M. Garcia-Fuentes, N. Csaba, M.J. Alonso, et al., Docetaxel-loaded polyglutamic acid-PEG nanocapsules for the treatment of metastatic cancer, J. Control. Release. 238 (2016) 263–271. doi:10.1016/j.jconrel.2016.07.048.