Improvement in antigen-delivery using fabrication of a grooves-embedded microneedle array

The skin, which has immunocompetent cells, is an attractive target for vaccine delivery. Intradermal immunization is the most effective immunization, though it requires considerable technical skill. A promising approach to intradermal immunization is microneedle array technology. This paper presents a new fabrication method for grooves-embedded microneedle arrays of a bio-compatible polymer and the immunization characteristics to ovalbumin delivered into mice by the microneedle arrays through the skin. The microneedles fabricated using a hot embossing process have a three-dimensional sharp tip, smooth or grooves-embedded shafts, and large bases. The height, base width, and thickness are 880 ± 20, 710 ± 15, and 145 ± 15 μm, respectively. To perform an immune response test, the ovalbumin-coated microneedle arrays were inserted into mouse skin and then, the titer of antibody to ovalbumin was analyzed. The increased number and deeper grooves of the microneedle induced a higher antibody response. These results suggest that the grooves-embedded microneedle array is loaded with more antigens than the smooth one and that the antigens are well delivered into the skin, though they are located on the deep grooves of the microneedles. In summary, the fabrication of grooves-embedded microneedles can supply an improved tool for intradermal immunization.