Characterization of tea water extracts and their utilization for dyeing and functionalization of fabrics of different chemical compositions

Abstract

Green, black, rooibos, and hibiscus tea (GT, BT, RT, and HT) aqueous extracts were prepared and characterized in terms of total flavonoids (TFC) and total phenolic (TPC) contents and antioxidant and antimicrobial activities. BT has the highest, while HT has the lowest TFC (1213 vs. 415 mg l–1), while the extracts’ TPCs (2283 – 7251 mg l–1) decreased in the following order: BT > GT > RT > HT. Their antioxidant activities of 78.1 – 93.1% and 97.8 – 100% were determined according to DPPH and ABTS methods, respectively. BT and especially GT aqueous extracts possessed mild effects against several microorganisms. All examined extracts have an affinity for dyeing wool, cellulose acetate, polyamide, and cotton, which is proven by the color strength values of 1.65–19.12. Wool, polyacrylonitrile, polyester, polyamide, cotton, and cellulose acetate functionalized with GT aqueous extract inhibited the growth of S. aureus and E. coli, while polyacrylonitrile and cotton also inhibited the growth of E. faecalis, and C. albicans, respectively. Wide inhibition zones for S. aureus were observed for fabrics functionalized with BT aqueous extract. Generally, the investigated fabrics showed very high (81.60 – 100%) ABTS radical scavenging ability independent of the extract used. TPCs have good linear correlations with the antioxidant activities of wool and polyacrylonitrile determined by the DPPH method. Fabrics with different chemical compositions dyed and/or functionalized with GT or BT aqueous extracts can be used to produce high-value-added medical textiles with therapeutic, prophylactic, and protective functions. They can find potential applications in wound treatment, especially in skin wounds that are susceptible to infection with S. aureus. Moreover, wool and cotton functionalized with GT or BT aqueous extract can also be considered for use in disposable medical textiles like bandages and gauze used in the wound-healing process.