Photothermal Responsive Microspheres-Triggered Separable Microneedles for Versatile Drug Delivery

Microneedle (MN) patches are promising stratagems for transdermal drug delivery owing to its minimal invasiveness and portability. Particularly, separable MN patches attract more attention for durable and long-term drug delivery. Here, a new strategy for designing controllably separable MN patches by integrating photothermal responsive phase-changing microspheres (MPs) into conical hydrogel MNs, is presented. Such MPs consist of near-infrared (NIR)-responsive black-phosphorus (BP) and phase-changing gelatin (GT), and are fabricated using a simple capillary microfluidic device. When the composite MN patch is exposed to NIR, the contained BP/GT MPs can transform light into heat, increase local temperature, turn into a liquid state, and form cavities in MNs, resulting in the convenient detachment of the backing plate and the needles by shear force. Subsequently, the embedded needles can sustainably release the drug. In addition to intelligently controlling the detachment of MNs, the BP/GT MPs can load macromolecular drugs and release them in response to NIR stimulation. Results further demonstrated that such controllably separable MN patch can effectively load and release two drugs to ameliorate disease progression for systemic lupus erythematosus treatment. These features indicate the practical values of controllably separable MN patches for versatile drug delivery and clinical applications.