Silk Fibroin Microneedles for Transdermal Vaccine\nDelivery

Abstract

Microneedles\nrepresent an exciting departure from the existing\nparenteral injection paradigm for drug delivery, particularly for\nthe administration of vaccines. While the benefit of delivering vaccine\nantigens to immunocompetent tissue in the skin has been established,\nthere have been varying degrees of success using microneedles to do\nso. Here, we investigate the use of silk fibroin protein to produce\nmicroneedles and evaluate their ability to deliver vaccines against\ninfluenza, <i>Clostridium difficile</i>, and <i>Shigella</i>. Fibroin protein from the silkworm <i>Bombyx mori</i> possesses\nsuitable properties for use in a microneedle system, including all-aqueous\nprocessing, mechanical strength in dried formats, biocompatibility,\nand the ability to temperature stabilize biomacromolecules. As such,\nthis biomaterial combines the processing and biocompatibility advantages\nof a dissolving microneedle system with the product stability and\nmechanical strength of coated insoluble microneedles. Through successful\nvaccination of mice against three separate antigens, we establish\nthat silk fibroin is well-suited for use as a solid-coated microneedle\ndelivery system and offers long-term potential similar to that of\nthe leading microneedle biomaterials.