Horseradish Peroxidase-catalyzed Polymerization Of Natural Phenols For The Dyeing Of Silk Fabrics

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.This study focuses on dyeing silk fabrics with natural phenol oxidatively polymerized by horseradish peroxidase.Additionally,it deals in depth with the dyeing mechanism and processing by enzyme catalyst.The polymerization mechanism between silk fabrics and gallic acid（GA）in the presence of horseradish peroxidase（HRP）has been studied.The results show that the dyeing mechanism for GA and silk fabric involved linking via the–NH₂ and–OH groups in silk fiber and the–OH groups in GA.This is 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℃;GA dosage,10 m M;HRP,6 U/ml,and H₂O₂,5 m M）.The color fastness of the resulting silk fabrics displayed high colorfastness in all the colorfastness tests performed.Gallic acid is synthesized using a new approach and arranged on three kind of templates（PEG,PEGMDE,Pluronic F68）using an horseradish peroxide（HRP）-catalyzed oxidative polymerization.The results confirmed that during the catalysis of gallic acid by HRP,the templates promoted the enzymatic polymerization in terms of the amount of poly（gallic acid）produced and the degree of polymerization.In addition,the template-treated silk fabrics exhibited enhanced wettability,anti-UV activity and color fastness than fabric treated with poly（gallic acid）in the absence of the templates.Upon analyzing the color depth,the K/S value of the silk fabrics dyed using the templates is significantly higher than that in the absence of the templates.The silk fabric dyed in the presence of templates showed higher fastness in all of the color fastness tests.In addition,the template effect of PEG on 13 natural phenols was also investigated.This may expand the application range of natural phenols for textile dyeing and functionalization,and provide new outlooks for the environmentally friendly production of natural functional fabric.It is successfully polymerized natural phenol（gallic acid,ferulic acid）and pyrrole（Py）monomers by oxidative polymerization of horseradish peroxidase（HRP）.Then,it is successfully colored silk fabrics using these chemicals.It is found that the oxidative polymerization of phenol and Py on silk fibers under mild reaction conditions using HRP produced technically conductive silk fabrics that combine the superior chemical and physical properties of silk fabrics with superior levels of electrochemical activity and thermal stability.Upon analyzing the color depth of the fabrics,we found that silk fabrics treated with Py have a darker color than silk fabrics dyed in the absence of Py.Additionally,the fabrics had slightly different levels of color fastness,but all were within the acceptable range.Silk fabrics treated with gallic acid/pyrrole（PGA/PPy）complexes polymerized using horseradish peroxidase have higher electrochemical activity than silk fabrics dyed with gallic acid alone.However,the degree of polymerization decreases.As a result,the UV protection and fastness of the silk fabric were lowered.To solve this problem,we studied the degree of polymerization of the complex and the functionality of dyed silk fabrics by applying a PEG template to the enzymatic polymerization of PGA/PPy.Consequently,the PGA/PPy/PEG complex has a higher degree of polymerization than the PGA/PPy prepared without PEG,indicating that the PEG template can promote the polymerization of PGA and PPy.As a result,we found that the presence of the PEG template improved the thermal stability and UV protection function of the dyed silk fabric,but did not impair the electrochemical activity of silk fabric.As a result of analyzing the color depth,it exhibited a higher K/S value compared to the dyed silk fabric in the absence of PEG.Additionally,its color fastness is improved.This technique expands the range of applications of natural phenols for textile dyeing and functionalization as well as providing new prospects for the enzymatically environmentally friendly production of natural functional fabric.Gallic acid-g-chitosan colored complex were produced using the HRP-catalyzed method.Then,these were used to successfully dye silk fabrics.Chitosan and gallic acid were polymerized via Ph–Ph,O–Ph and amino-phenyl（NH–Ph）bonds to form a dark yellow polymer that is successfully used to dye silk fabrics.In addition,significant color differences were observed between fabrics dyed without chitosan and fabrics dyed in the presence of chitosan.In particular,the fabric treated with the pre-polymerization dyeing process showed high antibacterial properties,color fastness,and color depth compared to other dyeing processes.We found that the optimum reaction conditions for dyeing silk fabrics are as follows:3 hour incubation period,50℃temperature,3 m M gallic acid;3g/L chitosan.Many researchers have adopted the pre-treatment process of chitosan on fabrics.However,when considering the results of color depth,antibacterial properties,and color fastness tests in this study,the pre-polymerization dyeing process should be considered first.This novel approach not only provides a simple route for the biological coloration of silk fabrics but also presents a way to prepare functional textiles with antibacterial properties.Currently,the known possible shades obtained for coloring silk fabrics using enzyme catalysts such as peroxidase are limited to a few shades of brownish tint.For the oxidative dyeing method using horseradish peroxidase（HRP）to become common,it must be able to produce a more diverse range of colors;this is a problem that must be solved.The purpose of this study is to obtain various colors by dyeing natural phenolic substrates using HRP in various buffers（acetate,citrate,phosphate buffer）and various p H levels（3～9）.We emphasized color diversity,which is achieved through the exploration of six different natural aromatic compounds:gallic acid（GA）,guaiacol（GAC）,p-coumalic acid（CA）,ferulic acid（FA）,catechol（CAC）and caffeic acid（CFA）.We also performed a methodological survey of reaction processing parameters.The colored products generated through HRP catalysis were analyzed using UV-vis.The color of the dyed fabrics is analyzed using the CIE L*a*b*color space system.As a result of the experiment,we obtained silk fabrics with various color depths from each buffer system.This suggests that the desired color and tone of dyed silk fabrics can be achieved by adjusting the buffer system and p H value.