Advances in microneedles for non-transdermal applications

Microneedles (MNs) have emerged as a promising tool for various therapeutic and diagnostic applications. While MNs have been prominently used for transdermal applications, recent advances in materials science, microfabrication technologies, and clinical devices enable the expansion of MNs to diverse non-transdermal applications.This review provides an overview of recent advances in the MN technology for non-transdermal applications. The classification of MNs and their applications to ocular, vascular, oral, mucosal, and cancer tissues are particularly highlighted.Recent efforts in MN designs have enabled and broadened MNs to many non-transdermal applications. It is anticipated to witness many new MN-mediated non-transdermal applications in the near future. By advancing MN systems with suitable properties for target tissues, it is possible to achieve high drug delivery efficiency that outperforms traditional drug delivery methods. Further endeavors in translation and commercialization of these novel technologies are equally critical.