Ultrathin and Breathable Silk-Protein Electronic Tattoos for Iontophoretic Transdermal Drug Delivery

Transdermal drug delivery (TDD) is emerging as a favorable alternative to traditional oral and injectable drug administration routes, offering a noninvasive, pain-free option with controlled and sustainable drug delivery. However, developing a TDD patch that delivers drugs with a high efficiency while being skin-friendly is still challenging. Here, we report an ultrathin and breathable iontophoretic patch for TDD application. The ultrathin dye-loaded electronic tattoo (UDET) consists of silk nanofibers (SNFs) and graphene. Cationic rhodamine B (RB) and methylene blue (MB) model drugs are incorporated in SNFs. The UDETs can be seamlessly affixed to nonuniform and pliable pigskin. The performance of the iontophoretic system can be fine-tuned by adjusting the applied voltage and duration of the iontophoresis process. The UDET delivers the RB and MB model drugs into pigskin up to a depth of >800 μm under a bias voltage of 20 V within 2 h. Additionally, to evaluate the potential for real-world applications, the diffusion of Dextran molecules of varying molecular weights was examined. The penetration depth of low molecular weight Dextran (Dex-10,000) was significantly higher than that of high molecular weight Dextran (Dex-70,000), demonstrating the influence of molecular size on diffusion efficiency. Our results show the UDET patch’s controllable and efficient delivery capability as well as underscore the potential of UDETs in augmenting TDD through controlled electric fields. This feature would be pivotal for the delivery of therapeutics in scenarios where conventional methods may be inadequate.