Polymerization and Dyeing Properties of Gallic Acid on Silk Fabric Catalyzed by Horseradish Peroxidase

Due to the increasing importance of environmentally friendly processes, the development of monomer synthesis and its polymerization using enzymes has been investigated throughout the world. In this paper, the polymerization mechanism between silk fabrics and gallic acid (GA) in the presence of horseradish peroxidase (HRP) has been studied. The polymerization mechanism was studied in detail using UV-Vis and Fourier transform infrared spectroscopy (FT-IR), and high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis. In addition, the dyeing properties and optimum reaction conditions were further investigated using the K/S values. The color fastness of the resulting silk fabrics has also been discussed. The results show that the dyeing mechanism for GA and silk fabric involved linking via the -NH 2 and -OH groups in silk fiber and the -OH groups in GA. This was probably formed via the formation of phenyl-phenyl, oxygen-phenyl, or amino-phenyl linkages. HRP significantly improved the dyeing properties of GA dyes toward silk fabrics. The optimum reaction conditions for dyeing silk fabrics have been proposed (Incubation period, 5 h; temperature, 50 °C; GA dosage, 10 mM; HRP, 6 U/ml, and H 2 O 2 , 5 mM). The color fastness of the resulting silk fabrics displayed high colorfastness in all the colorfastness tests performed.