Flavonoid-based yellow dye extract from safflower (Carthamus tinctorius L.) combined with chitosan for anti-bacterial and ultraviolet-protective functionalisation of silk

In the modern period, scientists are interested in the functional properties of natural materials. The present study is the first report on the use of safflower (Carthamus tinctorius L.) yellow dye extract combined with chitosan bio-mordant for enhancing the anti-bacterial and ultraviolet-protective activities of silk. The presence of flavonoid-based compounds in the dye extract was verified using liquid chromatography-mass spectrometry, Fourier transform-infrared spectroscopy, and ultraviolet-visible techniques. Moreover, alum mordant was also utilised in the silk dyeing process to compare the efficiency of bio and metallic mordanting agents. Experiment outcomes revealed that the chitosan mordanted-dyed silk sustained adequate fastness after being tested by washing, light, wet-rubbing, and dry-rubbing. In addition, superb bacterial inhibition percentages of 89% and 76% against Escherichia coli and Staphylococcus aureus, individually, were accomplished. Furthermore, the ultraviolet-protective behaviour of this silk sample was demonstrated with a 50+ ultraviolet protection factor and low-grade ultraviolet transmittance. This study reveals the great performance of an organic flavonoid dye as a sustainable and environmentally-friendly substance for dyeing and functionalising silk, as well as the efficacy of a green mordant over a metallic mordant in increasing the dyeability and functional activities of silk.