Nature-inspired safe and efficient hair dyes: beyond the traditional hair dyes

Abstract

The demand for green and non-toxic hair dyes has continued to grow in recent years as the majority of consumers prefer natural and healthy products. There are a series of pigments in nature that are used for color pigmentation and dyeing, such as melanin in animals and curcumin in plants. Accordingly, these nature-inspired novel hair dyes are recognized as having the potential to replace conventional hair dyes for their bio-friendly and less irritating properties. Although several nature-inspired hair dye products and their potential properties, including antistatic, antioxidant, and antibacterial properties, have been proposed, their complex pigmentation mechanisms are not fully understood. The present feature article covers several nature-inspired pigments and strives to summarize the possible pigmentation mechanisms for hair dyeing. A special focus was given to the color-tuning techniques of these novel hair dyes, such as optimization of polymerization, pigment compounding, and tuning of the energy level structure.