Formulation, Characterization, and In Vivo Immunogenicity of Heat-Stabilized Dissolvable Microneedles Containing a...

Vaccination has significantly improved health outcomes, but implementing vaccination efforts in low and middle-income countries, particularly in warmer climates, presents challenges. Microneedle technology has been developed for its simple and relatively painless applications of vaccines. However, a few hurdles must be overcome before widespread acceptance, including evaluating the safety and biocompatibility of the polymer used to fabricate these microneedles. Additionally, it is important to demonstrate reliable immune responses comparable to or better than those achieved through traditional administration routes. This study aimed to develop and evaluate dissolvable microneedles loaded with a novel virus-like particle (VLP) vaccine, focusing on their fabrication, characterization, thermostability, and preclinical immunogenicity.

Microneedles were fabricated using the micro-molding technique with polyacrylic acid (PAA) polymer, incorporating a novel VLP vaccine targeting arbovirus. Characterization studies assessed microneedle sharpness, skin insertion force, and VLP integrity. We also investigated the thermostability of the vaccine after storing the microneedles at elevated temperatures for approximately 140 days. Vaccine immunogenicity was assessed in mice, and transdermal (microneedle) delivery was compared with intramuscular (hypodermic needle) delivery.

The study successfully fabricated and characterized VLP-loaded microneedles capable of skin insertion while maintaining vaccine integrity after exposure to extreme storage conditions. These microneedles elicited robust and long-lasting antibody responses comparable to those achieved through intramuscular administration.

This study combines a novel VLP-based vaccine with dissolvable MNs fabricated under pH-neutral conditions, preserving antigen integrity and immunogenicity after high-temperature storage. This vaccine delivery platform addresses critical gaps in thermostability and needle-free vaccine delivery for resource-limited settings.