Sequential Intradermal Delivery of Antigen and Adjuvant Using Separate Microneedle Patches Enhances Immunity

Recombinant protein–based vaccines are safe and scalable, but often show low immunogenicity. Adjuvants improve responses, yet co-delivery with antigens may induce excessive local inflammation or reduce antigen stability. Most microneedle array patch (MAP) platforms co-formulate both components, limiting loading flexibility, increasing unfavorable interactions, and lacking temporal control in skin. Here, two distinct microneedle patches are applied sequentially to the same site to spatially and temporally separate delivery, preserve adjuvant activity, ensure efficient intradermal antigen delivery, and enhance immune responses.