Fig. 7.

Technologies toward single-shot vaccines. (A) Schematic of pulsatile release PLGA microspheres. Initial release burst results from release of antigen from on or near the surface of the microspheres. This phase is followed by a lag phase as the PLGA polymer starts to degrade. The polymer then fully degreades leading to a second burst of antigen. (B) Humoral immune response against a polio vaccine where the pulsatile release platform (labeled F1) was tested against bolus protein injections. (C) Representative TEM of 3D microstructures that contain a fillable reservoir for loading vaccine formulations.(A-C adapted from [320]). (D) Schematic of potential multi-burst vaccine strategy elicited from a single shot. Microstructures composed of varying PLGA modifications degrade at different rates in vivo leading to burst releases of vaccines at different timepoints. (E) Humoral immune response following immunization with ovalbumin. The immune response induced by core-shell microstructures were compared to that of bolus injection (Adapted from [322]).