Chitosan polysaccharide as a renewable functional agent to develop antibacterial, antioxidant activity and colourful shades on wool dyed with tea extract polyphenols.

Chitosan is a potential renewable, versatile amino polysaccharide which has been approved by food and drug administration for use in food, cosmetics, pharmaceuticals and other industries. In order to determine if chitosan can be utilized in the development of colourful and multifunctional wool fabric without the need of toxic metal salt mordants, we have investigated the colouring, radical scavenging and antibacterial activity of wool dyed with tea extract polyphenols using chitosan as a green pre-treatment finishing agent. UV-vis analysis confirmed the optical properties of tea polyphenols, while Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) and Thermogravimetric analysis (TGA) spectroscopic characterizations demonstrated binding, surface morphology and thermal stability properties of chitosan coated wool. Colour spectrometry data obtained in terms of CIEL*a*b* values showed an outstanding effect of the chitosan pre-treatment. The Camellia sinensis (tea) extract dyed wool yielded interestingly elegant pale to golden yellowish colours with acceptable wash fastness properties. The chitosan gets its affinity for the wool via hydrogen bonding, electrostatic and van der Waals interactions. The results also showed that chitosan pre-treatment imparts excellent radical scavenging and antibacterial activity against E. coli and S. aureus, and thus offers new opportunities in the realm of natural dyeing.