Programmable and monitorable intradermal vaccine delivery using ultrasound perforation array

Skin disruptions of micrometer- or submillimeter-diameter generated by microneedle or laser ablation can be used for intradermal vaccination. Here, we report a new skin-disruption method that uses highly-focused ultrasound to controllably perforate murine skin. We showed that programming of ultrasound parameters varied skin perforation area from 0.078 ± 0.045 mm² to 1.295 ± 0.279 mm². The skin perforation area increased with increasing ultrasound pressure and exposure time, and decreased with increasing ultrasound frequency and incidence angle. Moreover, successful perforation can be monitored using ultrasound pulse-echo imaging. We found that ultrasound perforation elevated local skin expression of heat shock protein 70 and effectively attracted MHC II-positive immune cells after intradermal delivery of Hepatitis B surface antigen (HBsAg). We demonstrated that the antigen dose delivered by ultrasound perforation can be effectively modulated via programmable perforation arrays (comprised of 1 × 2, 1 × 3, 1 × 5 or 3 × 3 areas of exposure). Using a 1 × 3 perforation array for vaccination, the measured mean optical density (OD) value of serum anti-HBsAg IgG was slightly higher than that of intradermal injection. The addition of an adjuvant of recombinant cholera toxin B further increased OD values of anti-HBsAg IgG. This ultrasound perforation method holds great promise for monitorable and programmable intradermal vaccination.