Customized flexible hollow microneedles for psoriasis treatment with reduced‐dose drug

Microneedles, especially hollow microneedles (HMNs), play an important role in drug delivery, but most of the current HMNs are manufactured based on silicon microfabrication (lithography, etching, etc.), which are slightly conservative due to the lack of low‐cost, batch‐scale and customized preparation approach, especially for the HMNs with flexible substrate. For the first time, we propose the use of a high‐precision 3D printed master mold followed by a dual‐molding process for the preparation of HMNs with different shapes, heights, and inner and outer diameters to satisfy different drug delivery needs. The 3D printed master mold and negative mold can be reused, thereby significantly reducing the cost. HMNs are based on biocompatible materials, such as heat‐curing polymers or light‐curing resins. The thickness and rigidity/flexibility characteristics of the substrate can be customized for different applications. The drug delivery efficiency of the fabricated HMNs was verified by the in situ treatment of psoriasis on the backs of mice, which required only a 0.1‐fold oral dose to achieve similar efficacy, and the associated side effects and drug toxicity were reduced. Thus, this dual‐molding process can reinvigorate HMNs development.