A skin-compatible electronic tattoo for light-triggered transdermal delivery of drugs with diverse physicochemical properties

Abstract

Transdermal drug delivery is an attractive alternative to oral administration and hypodermic injection, but the skin remains a barrier to drug penetration. Here, we describe an ultrathin, flexible, and breathable electronic tattoo (e-tattoo) consisting of cellulose nanofibers, graphene, and silk fibroin for photothermally triggered transdermal delivery of drugs with diverse physicochemical properties. The amphiphilic nature and skin compatibility of silk fibroin enables surfactant-free encapsulation of hydrophobic and hydrophilic drugs in a single silk reservoir and delivers drugs into the dermal layer efficiently. The mechanical and electrical stability, and breathability of the e-tattoo enable long-term and reliable epidermal application. Under exposure to lowpowered red LEDs, graphene generates localized heat and provides for enhanced transdermal diffusion. Various dyes and drugs, such as rhodamine B, quercetin, dextran, and skin-whitening agents (adapalene, retinol, nicotinamide, and arbutin), can be encapsulated in the silk reservoir, enabling transdermal and depth-controlled delivery through a photothermally triggered electronic tattoo. Histological studies reveal significant melanin suppression (> 40 %) in pigmented skin models, and the biocompatibility of the e-tattoo. This research provides a step forward to programmable transdermal drug delivery for personalized cosmetics and therapeutics.