Lawsone and Indigo-Loaded Sepiolite Nanofibers for Hair Coloring with Sustained Release

Abstract

Natural clay materials have been present in people’s lives for centuries, from pottery and house construction to food processing and cosmetics, proving their utility and safety for human use. Recent developments in tubule and fiber clay systems demonstrated their efficacy at carrying chemical loads in their inner tunnels of nanometer diameters. We exploited nanofibrous sepiolite possessing 0.4 × 1.1 nm cross-sectional tunnels for loading with dyes and drugs followed by their spontaneous assembly on human hair from an aqueous suspension to form a 1–2 μm-thick coating with a concentration near cuticle edges. This bio-friendly process avoids any chemical reactions on the hair and results in a simple and safe coating for coloring or topical medical treatment. It is especially valuable for the application of water-insoluble dyes, such as lawsone and indigo. We successfully loaded lawsone and indigo into the sepiolite and applied the composite onto hair, creating stable brown and blue coatings. Up to 80% of the initial hair color is preserved after six shampoo washes. Coatings of the dye-sepiolite composite on permed hair reduced the surface roughness, enhancing the hair volume and color performance. We also loaded sepiolite with drugs (e.g., antilice permethrin or ivermectin), which could be used for topical hair and scalp treatments with sustained release.