Eco-friendly Simultaneous Dyeing and Synthesis of Silver Nanoparticles on Silk Yarn Using Anthocyanin Extracts from Melastoma malabathricum L. Fruits

Abstract

To address the challenge of finding sustainable and effective methods for simultaneously dyeing silk yarn and incorporating antibacterial activity without harsh chemicals or complex procedures, a successful study has demonstrated a sustainable method for dyeing silk yarn and producing silver nanoparticles (Ag NPs) simultaneously. This eco-friendly approach utilizes anthocyanin components extracted from Melastoma malabathricum fruits as both a natural reducing agent for Ag NPs and a colorant for the silk. The reduction of silver ions to form stabilized Ag NPs was successfully achieved at pH 10, resulting in an average particle size of 86.34 ± 17.75 nm, and leading to the coating of a silk yarn surface. After dyeing and coating with Ag NPs under basic conditions, the treated silk yarn exhibited an excellent yellow colour (positive b* value), good colour strength (K/S) of 4.09 with the colour difference (∆E*) of 5.49, and good light fastness properties after exposure to simulated sunlight. Silk yarn treated at a basic pH exhibits superior antibacterial activity against Staphylococcus aureus and Escherichia coli compared to yarn treated at acidic or neutral pHs, both before and after exposure to simulated sunlight. This improved bioactivity is demonstrated by log10 reductions in colony-forming units (CFUs) exceeding 4. © The Author(s) 2025.