Phenolic compounds such as hydroquinone, catechol and ferulic acid can polymerise and therefore develop deep colours when treated with peroxidase and laccase enzymes. We have attempted to apply this phenomenon for wool dyeing. Wool was padded with phenolic compounds and deep colours were developed by enzymatic treatment in buffer solutions. Mordant with chromium compounds or heating under the conditions of acid catalysis was available for fixation of these coloured compounds on the wool fibres.Enzymatically dyed wool samples.[GRAPHICS

Gübitz, Georg M.

Paulo, Artur Cavaco

Shin, Hoonsik

Macromolecular Materials and Engineering

Universidade do Minho: RepositoriUM

Macromol. Mater. Eng. 2001, 286, 691–694 691“In Situ” Enzymatically Prepared Polymers for WoolColorationHoonsik Shin,1 Georg Guebitz,2 Artur Cavaco-Paulo* 11 Departamento de Engenharia Txtil, Universidade do Minho, 4800 Guimares, PortugalFax: +351-53-814-5480; E-mail: artur@det.uminho.pt2 Graz University of Technology, Department of Environmental Biotechnology, Petersgasse 12, A-8010 Graz, AustriaIntroductionThe textile industry is looking for new coloration meth-ods for dyeing and enzyme technology can represent analternative for this approach. Oxydoreductase enzymessuch as laccases (benzenediol: oxygen oxidoreductase,EC 1.10.3.2) and horseradish peroxidase (donor: hydro-gen peroxide oxidoreductase, HRP, EC 1.11.1.7) can pro-vide novel ways for wool coloration in the face of actualstate of the art of these enzymes.HRP has been reported as a very useful enzyme for thesynthesis of phenolic polymers.[1] A free radical at thehydroxyl position in the phenolic compounds is formedby HRP enzymatic oxidation through activation withhydrogen peroxide. This free radical moves along the aro-matic ring and contributes to the coupling between mono-meric units.[2] Scheme 1 shows a simplified scheme of themechanism of the enzymatic polymerisation reaction. Asimilar enzymatic reaction proceeds for the system usingenzyme laccase.[3, 4]Many enzymatically polymerised phenolic compoundstend to have a characteristic colour because polyphenolforms a big conjugated structure along the main chain.Hydroquinone is also one of the phenolic compounds thatshow a colour change when it is catalysed with oxidore-ductases. Enzymatic application for human hair dyeinghas been carried out with hydroquinone under activationwith laccase.[5] This investigation aims to reach a safehair dyeing without using hydrogen peroxide. Laccasecatalyses the oxidation of hydroquinone, producing adelocalized free radical at the oxidised intermediate. Col-ouring products of dimer, oligomer and polymer result bya radical coupling reaction between the intermediates.Communication: Phenolic compounds such as hydroqui-none, catechol and ferulic acid can polymerise and there-fore develop deep colours when treated with peroxidaseand laccase enzymes. We have attempted to apply thisphenomenon for wool dyeing. Wool was padded withphenolic compounds and deep colours were developed byenzymatic treatment in buffer solutions. Mordant withchromium compounds or heating under the condition ofacid catalysis was available for fixation of these colouredcompounds on the wool fibres.Macromol. Mater. Eng. 2001, 286, No. 11 i WILEY-VCH Verlag GmbH, D-69451 Weinheim 2001 1438-7492/2001/1111–0691$17.50+.50/0Enzymatically dyed wool samples.Scheme 1. Enzymatic polymerisation of phenol compounds.692 H. Shin, G. Guebitz, A. Cavaco-PauloThis phenomenon is interesting because the colour can beobtained easily from the enzymatic reaction and thereforecan be available for textile dyeing.In this study, we try to dye wool fabric including mor-dant processing in an enzymatic method. We investigatethe effects of dyeing conditions such as hydroquinoneconcentration, enzyme concentration and hydrogen per-oxide concentration on the enzymatic dyeing towardswool fabric. We also discuss the enzymatic dyeing ofwool with ferulic acid through curing processing.Results and DiscussionApplication of HydroquinoneColour in wool can be developed using several phenoliccompounds such as hydroquinone (brown-blacks), cate-chol (greys), dopamine (greys), guaiacol (colourless) andferulic acid (yellows) after treatment with HRP. Woolsamples were rinsed with running water without anyfurther treatment after the enzymatic treatment. Theyshow that each of these samples have different character-istic colours which depend on the different phenolic com-pounds chosen for the enzymatic dyeing. This result indi-cates that different kinds of coloration can be performedby selection of phenolic compounds. Hydroquinone andferulic acid will be mostly employed as phenolic com-pounds in this study.The wool fabric used for enzymatic treatment has pre-viously been padded with hydroquinone. The colour ofthe wool fabric changed to brown during enzymatic treat-ment as shown in Scheme 2. This colour change may beexplained by the fact that hydroquinone on the fabric isoxidised by enzymatic oxidation, then forming dimer, oli-gomer and polymer. Evidence for enzymatic polymerisa-tion using similar conditions was described before. Lac-case was also employed for enzymatic dyeing of wool.Wool fabric that was previously padded with hydroqui-none was also coloured to brown during enzymatic treat-ment with laccase. This is the same effect as when HRPis used for enzymatic dyeing, indicating that the enzy-matic reaction using laccase may be similar to the enzy-matic reaction using HRP, as shown in Scheme 1.Washing tests were carried out on dyed wool fabrics asdescribed in the Experimental Part. Concentration of thehydroquinone solution was 40 g/l. The results are shownin Figure 1. The K/S value was employed to evaluate thecolour depth for the wool fabrics. The reflectance valuesat 700 nm are employed because of the biggest differencebetween the values at this wavelength. One of them wastreated with potassium dichromate solution, while theother was not treated. Colour depth of the dyed fabricdecreased after the washing test. However, the decreasingcolour depth could be reduced by mordant treatment.This indicates that the chromium combines with quino-noid oxygen and hydroxyl group of the enzymaticallytreated hydroquinone in wool fabric.The diagram in Figure 2 shows the colour depths ofwool fabrics that were padded previously with hydroqui-Scheme 2. Enzymatically dyed wool samples.Figure 1. Washing test of enzymatically dyed wool fabric thatwas previously padded with hydroquinone.Figure 2. Colour depths of enzymatically dyed wool fabric atvarious concentrations of hydroquinone and on various activitiesof HRP.“In Situ” Enzymatically Prepared Polymers for Wool Coloration 693none solutions in several concentrations and treated withHRP solution with a concentration of 25000 units/l. Theconcentration of hydroquinone solution is in the range ofsaturation, i.e., 60 g/l. This Figure shows that the colourdepth of wool fabric increases with increasing concentra-tion of hydroquinone in the padding solution, indicatingthat the colour depth of the fabric can be controlled bythe concentration of hydroquinone padded on the woolfabric.The colour depth of wool fabric against enzyme con-centration is also shown in Figure 2. Wool fabric hasbeen padded previously with hydroquinone solution (con-centration 60 g/l). Colour depth increases remarkablywith increasing enzyme activity to 6250 units/l, then theplot is nearly getting flat in the subsequent activity. Thisindicates that 6250 units/l is sufficient activity to oxidisealmost all hydroquinone padded on the fabric, for a 1 hdyeing process. The K/S value of the untreated fabric isabout 0.4. This value is higher than the value of theuntreated fabric shown in the other plot, which is about0.1, because this untreated fabric has previously beenpadded with hydroquinone.In Figure 3, the colour depth of wool fabric is shownagainst concentration of added hydrogen peroxide inenzyme solution. The concentration of hydroquinonesolution used for padding the wool fabric was 40 g/l. Col-our depth of wool fabric increases with increasing con-centration of hydrogen peroxide until 5 ml/l. The colourdepth, however, starts to decrease in the subsequent con-centration of hydrogen peroxide. This indicates that ahigh amount of hydrogen peroxide apparently inhibits theHRP reaction, although hydrogen peroxide is necessaryfor the HRP catalytic reaction. In this case, it seems thatthe enzyme loses its activity because hydrogen peroxidemay oxidise and may inhibit the protein enzyme. A suita-ble concentration of hydrogen peroxide should be appliedin order to increase the colour depth obtained in the enzy-matic reaction without damage of the protein enzyme.Application of Ferulic AcidFerulic acid was also used as phenolic compound to dyewool fabric using the enzymatic method. The diagram inFigure 4 shows the reflectance value of wool fabric thatwas padded previously with ferulic acid and treated withHRP. This fabric has been coloured by enzymatic treat-ment. The Figure shows, however, that the wool fabricafter soaping presents a lighter colour than the untreatedwool fabric. This indicates that the coloured ferulic acidon the wool fabric has been removed throughout soapingbecause the ferulic acid was not strongly fixed on the fab-ric. On the other hand, the wool fabric treated underacidic conditions after enzymatic treatment had a yellowcolour even after soaping. This indicates that the colouredferulic acid has been fixed on the wool fabric during boil-ing under acid condition. Ferulic acid contains usefulreactive sites such as double bond and carboxyl group,except for hydroxyl group. These sites can be expected tobe responsible for fixation of ferulic acid on the wooleven without mordant. The fixation mechanism, however,is not clear at the present.ConclusionWe have attempted to obtain new dyeing methods usingan enzymatic reaction that contributes to the colorationfor wool. It is known that particular phenolic compoundssuch as hydroquinone, catechol, dopamine, guaiacol andferulic acid can be used for the enzymatic dyeing ofwool. It was expected to obtain various characteristic col-ours of wool fabric by selection of the phenolic com-pounds.The colour depth of enzymatically dyed wool fabricscan be changed depending on the controllable amount ofhydroquinone on the fabric. Mordant processing withchromium compound was available for fixation of thiscoloured hydroquinone derivative on the wool fabrics.The hydroquinone on the fabric should be oxidised into aradical form by enzymatic oxidation, then forming dim-mer, oligomer and polymer. This enzymatically poly-merised hydroquinone, which has a big conjugated struc-ture along the main chain, should cause the coloration ofFigure 3. Colour depths of enzymatically dyed wool fabrics atvarious concentrations of hydrogen peroxide.Figure 4. Colour of wool fabric that was padded with ferulicacid and then treated with HRP.694 H. Shin, G. Guebitz, A. Cavaco-Paulothe wool fabric. To obtain a higher colour depth, appro-priate dyeing conditions such as concentration of enzymeand concentration of hydrogen peroxide should be used.Ferulic acid can be also used for the enzymatic dyeingof wool. In this case, coloured ferulic acid can be fixedrather strongly on the wool fabric through boiling treat-ment under acidic conditions instead of using chromiumas mordant.Experimental PartMaterialsRaw wool fabric was obtained from Albano Antunes Mor-gado, Lda and was used in this study without any furthertreatment. Hydroquinone, catechol, dopamine, guaiacol andferulic acid from Sigma were used as phenolic compounds.The chemical structures of these compounds are representedin Scheme 3. Peroxidase from horseradish (Type VI-A)(HRP, EC 1.11.1.7), supplied in powder form, and laccase(EC 1.10.3.2), supplied in solution form, were purchasedfrom Sigma. These enzymes are classified as oxidoreduc-tases. 30% hydrogen peroxide solution was used as oxidisingagent. The buffer systems used in this study were sodiumphosphate – disodium hydrogen phosphate (0.1 m) for pH7.0and acetic acid – sodium acetate (0.1 m) for pH5.0. HRP wasdiluted in the buffer solution (pH7.0) and kept in a refrigera-tor as stock solution. This stock solution contains 5000units/ml (Sigma Units). A 29.4 g/l potassium dichromatesolution was prepared for mordant processing. Householdsurfactant (5 g/l) was used for washing wool fabrics.Enzymatic Dyeing1 g of hydroquinone was dissolved in 20 ml of water for 1 gof a wool fabric (8 cm68 cm). The fabric was immersed ina hydroquinone solution for 1 h at room temperature andpadded in 100% pick up ratio. Two enzyme solutions wereprepared using HRP and laccase, respectively. One was pre-pared with 0.1 ml of the HRP stock solution, 0.1 ml of thehydrogen peroxide solution and 20 ml of the buffer solution(pH7.0). The other one was prepared with 0.1 ml of the lac-case stock solution, however without using hydrogen perox-ide, in a buffer solution in the same conditions with HRPsolution. The wool fabrics were dipped in the enzyme solu-tion without stirring for 1 h at room temperature. After theenzymatic reaction, the fabrics were slightly rinsed withwater to remove residual compounds on the fabrics. 20 ml ofthe potassium dichromate solutions were employed to mor-dant the fabrics for 1 h at room temperature. The colouredfabrics were thoroughly rinsed with water at 858C for15 min to remove residual compounds.On the other hand, ethanol (50%) was used as solvent toprepare the ferulic acid solution (25 g/l) because this com-pound has a very low solubility in water. The wool fabricwas padded with this ferulic acid solution under the sameconditions as mentioned before. After drying, each wool fab-ric was treated with 20 ml of enzyme solution containing0.1 ml of the HRP stock solution, 0.1 ml of the hydrogen per-oxide solution and 20 ml of the buffer solution (pH5.0 or7.0), at room temperature during 1 h. After the enzymatictreatment, the temperature of the enzyme solutions wasraised up to 1008C for 40 min and kept at that temperaturefor 1 h. Each fabric was washed with 100 ml of the surfactantsolution at 718C for 30 min to remove residual compounds.Colour MeasurementColour depth was evaluated in terms of K/S values and thesewere calculated using Kubelca-Munk’s equation. For eachfabric sample, five reflectance measurements were made andthe arithmetic mean of these determinations was used forK/S. The reflectance values were measured with a Spectra-flash SF600+CT of Datacolor International with illuminatingD65 at 108 observer.Kubelca-Munk0s equation : K=S  1ÿ R22Rwith R = reflectance.Washing TestThe wool fabric was put into 300 ml of a pot containing100 ml of 0.5% commercial surfactant (commercial name“xau”) solution. The test was carried out for 30 min at 718Cunder 20 rpm.Received: May 16, 2001Revised: August 7, 2001[1] J. S. Dordick, M. A. Marletta, A. M. Klibanov, Biotechnol.Bioeng. 1987, 30, 31.[2] A. M. Rao, V. T. John, R. D. Gonzalez, J. A. Akkara, D. L.Kaplan, Biotechnol. Bioeng. 1993, 41, 531.[3] F. F. Bruno, J. A. Akkara, L. A. Samuelson, D. L. Kaplan,B. K. Mandal, K. A. Marx, J. Kumar, S. K. Tripathy, Lang-muir 1995, 30, 889.[4] T. Oguchi, S. Tawaki, H. Uyama, S. Kobayashi, Macro-mol. Rapid Commun. 1999, 20, 401.[5] US 5948121 (1999), Novo Nordisk A/S, invs.: A. V. Dor-rit, H. S. S. Niels, R. V. S. Karen.Scheme 3. Chemical structures of phenolic compounds.

"In Situ" enzymatically prepared polymers for wool coloration

http://repositorium.sdum.uminho.pt/bitstream/1822/1939/1/37.pdf

"In Situ" enzymatically prepared polymers for wool coloration

Abstract

Similar works

Full text

Available Versions

Universidade do Minho: RepositoriUM