Biosynthesis, Characterization, and Cosmetic Applications of Metallic Nanoparticles in Hair Dye and Skin Care

Abstract

In the context of sustainable development and green chemistry, this study explores the eco-friendly synthesis of silver (Ag) and zinc oxide (ZnO) nanoparticles using aqueous extracts from Curcuma longa (turmeric), Lawsonia inermis (henna), Hibiscus sabdariffa (hibiscus), and Lavandula stoechas (tasalgha). The biosynthesized nanoparticles were thoroughly characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD), confirming their nanoscale dimensions, crystalline nature, and morphologies. These nanoparticles were subsequently incorporated into cosmetic formulations, namely skin care creams and herbal-based hair dyes . The creams were evaluated for physicochemical properties including pH, stability, and type of emulsion, as well as for pharmacological activities such as antioxidant and antibacterial effectiveness. The antioxidant activity was quantified using the DPPH assay, with IC₅₀ values indicating significant radical scavenging properties, especially in creams containing AgNPs. Antibacterial tests showed selective activity against Staphylococcus aureus (Gram-positive), with no effect on Escherichia coli (Gram-negative). Additionally, dyeing trials on white and brown hair demonstrated good adherence and color stability, particularly in nanoparticle-based formulations . This study confirms the potential of plant-mediated nanoparticles as multifunctional ingredients in natural and sustainable cosmetic products, combining therapeutic and aesthetic benefits.