3D-Printed Transdermal Microneedles for Allergen Immunotherapy

Abstract

Allergen immunotherapy or “allergy shots” are delivered as fast-acting intravenous (IV) injections given to patients suffering from chronic allergies. However, in rural settings, patients must travel long distances for a single injection, significantly adding to patient costs, and costs to an already over-burdened health-care system. We hypothesized that minimally invasive, painless, self-administered 3D (three-dimensional) printed microneedles could be a better alternative in these scenarios and could be provided in conjunction with tele-medicine. For this study, 3D printed microneedles were printed using Formlabs stereolithography (SLA) printers and clear V4 material. Different parameters were calibrated including layer thickness, size, shape, material, and needle orientation, to enable dermal puncture with minimal breakage. Our results show that a Pyramid Needle Model (needle array: 1(L)x1(W)x0.5(H) cm; needle dimensions: 200(L)x200(W)x800(H) µm; 500µm (spacing); 1µm (tip diameter); 45° angle; 0.025mm layer-thickness) was the best microneedle model produced through our experiments. Microscopy and porcine skin puncture testing confirmed the functionality of these needles in the laboratory. Taken together, our results showcase the feasibility of fabrication of transdermal microneedles through 3D printing, providing a fast and effective solution for self-administered painless drug delivery. Future work will focus on improving microneedle design to enable allergy-drug loading and delivery.