Engineering immunity via skin-directed drug delivery devices.

Extensive research is underway to discover a safe and effective vehicle to deliver the vaccines at the desired cutaneous site. These efforts majorly comprise the development of a fit-to-purpose vehicle for in-situ intracutaneous vaccine delivery for achieving the systemic cellular and humoral response to combat infectious diseases. Advancements in nanoscience, bioengineering, and skin science provided much support to vaccine adjuvant development. However, the bench-to-bed side translation of vaccines is still unsatisfactory. A skilfully designed vaccine delivery program aiming to translate the product into market use must address safety, efficacy, scaleup, reproducibility, cost of production, self-administrative potential, and regulatory concerns. This review provides deep insights into skin immunization approaches like mucosal vaccines, cellular/molecular immunological responses, and antigen-adjuvant combinations in modulating immunity. Further, the manuscript discusses distinct vaccine delivery systems used to date for engineering skin immunization, including microparticles, nanoparticles, spherical nucleic acids, STAR particles, niosomes, dendrimers, ethosomes, liposomes, and microneedles. The manuscript will interest researchers working towards developing a next-generation fit-to-purpose vehicle for intracutaneous vaccine delivery.