effects of alkyl chain lengths of gallates upon enzymatic wool functionalisation
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Journal of Molecular Catalysis B: Enzymatic 67 (2010) 231235
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Journal of Molecular Catalysis B: Enzymatic
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Kh.M. Ga MGroup of Molec versity
a r t i c l
Article history:Received 9 MaReceived in reAccepted 18 AAvailable onlin
s ona ont prolly grn. Thn verth thon w
Wool isdue to its lightness, softness, warmness, and smoothness. How-ever, the complex chemical composition and architecture of thewool bres is responsible for some undesirable properties such ashigh water absorption, felting in mechanical wet operations, andlimited UV protection during use. Under proper temperature andhumidity thtion and prdamage, sktextiles leadof elasticityby washingwool goodsto keep cleagents.
For thesebe protectebres andantibacteriatextile goodant activitrepellence)properties.from their h
sphth thlic a
used as food additives due to their antioxidant activity [7,8].The alkyl gallates, having a molecular structure composed of ahydrophilic head (phenolic ring) and a hydrophobic alkyl chain,have also been reported to have antifungal and antibacterialactivity [9,10]. Though different studies investigated the relation
1381-1177/$ doi:10.1016/j.e wool materials could be a good medium for genera-opagation of microorganisms  that could cause brein irritations, and infections . Microbial growth ons to odour development, discolouration, and even lossand tenacity . The infestation can be removed onlyat boiling temperature where structural changes of themight occur. Moreover, the protein bres are difcultan and are easily damaged by conventional cleaning
reasons, thewoolmaterials of high-grade clothesmustd against microbial attack to prevent damage of thegrowth of pathogenic microorganisms. In addition tol nish, nowadays there is a great demand to produceds with multifunctional properties such as antioxi-y and self-cleaning properties. Hydrophobicity (waterof textiles is frequently associated with self-cleaningThe self-cleaning action of hydrophobic coatings stemsighwater contact angles.Water on these surfaces forms
ding author. Tel.: +34 937398761; fax: +34 937398225.ress: email@example.com (T. Tzanov).
between the hydrophobic chain lengths and alkyl gallates prop-erties, there is no clear consensus regarding the effect of the chainlength upon the antioxidant and antibacterial properties of gallates.
In addition to the antioxidant and antibacterial activities, thealiphatic chain present in the chemical structure of these com-pounds would provide hydrophobic properties as well. Therefore,it could be expected that the modication of wool with alkyl gal-lates would provide a combination of self-cleaning, antimicrobialand antioxidant properties.
A proof-of-concept one-step enzymatic process using laccasein aqueousorganic media for covalent grafting of dodecyl gal-late (DG) on wool has been recently described . Laccase isable to catalyse the oxidation of a wide range of aromatic com-pounds using molecular oxygen as electron acceptor and has beenreported to retain activity in some water miscible organic solvents,e.g. ethanol [17,18]. The reaction was carried out in an 80/20 (v/v,%) aqueousethanol mixture to balance the need for dissolving DGwith the need for maintaining the catalytic activity of laccase. Theenzymaticgraftingofdodecyl gallateonwoolprovidedamultifunc-tional textile material with antioxidant, antibacterial and waterrepellent properties.
see front matter 2010 Elsevier B.V. All rights reserved.molcatb.2010.08.011of alkyl chain lengths of gallates upon e
ffar Hossain, Mara Daz Gonzlez, Jos Mara Dagular and Industrial Biotechnology, Department of Chemical Engineering, Technical Uni
e i n f o
rch 2010vised form 13 August 2010ugust 2010e 24 August 2010
a b s t r a c t
The covalent grafting of alkyl gallateaqueousethanol mixture provided inidant, antibacterial and water repellendodecyl gallate have been enzymaticalength on wool functional modicatioan aqueousorganic medium has beegroups in the FTIR spectra, togetherwithe covalent grafting of ester gallatesrepellent as well as antioxidant propplay an important role on wool functi
a natural protein material largely used for clothing
Gal/ locate /molcatb
ymatic wool functionalisation
onmany, Tzanko Tzanov
of Catalonia, C. Colom, 11, 08222 Terrassa, Barcelona, Spain
wool through a laccase catalysed reaction in 80/20 (v/v, %)e-step process a multifunctional textile material with antiox-perties. Gallic acid and its alkyl esters ethyl, propyl, octyl andafted on wool bres in order to study the effect of alkyl chaine capacity of laccase to oxidise these phenolic compounds inied by electrochemical techniques. The increase of CH2, CH3eXPS analysis of the enzymaticallymodied fabrics conrmedool. The result obtained in this work for antibacterial, watershow that the length of the alkyl chain of gallates molecule
sation. 2010 Elsevier B.V. All rights reserved.
erical droplets that readily roll away carrying dust andem [4,5].cid and its alkyl esters are natural compounds 
232 Kh.M. Gaffar Hossain et al. / Journal of Molecular Catalysis B: Enzymatic 67 (2010) 231235
In the cuent aliphatioctyl gallateication ofwantioxidantcidate theproperties o
Laccaseprotein/g soUK. Enzymdised per msodium tarradical (DP(GA), ethyldodecyl gacompoundssion werePanreac. Allcommercia
VoltammType III (Eclab GPES soout in a 20tion. The wsurface diamelectrodeswtrode, respeachieved byolish, Buehlwashing inwith laccaswas droppedry for 15m
2.3. Wool p
Woven 1washedpresurfactant C20:1 in a labpH 9) at 40
same bath ratio with 0.1mL/L of 30% H2O2 (0.1M Na2CO3, NaHCO3buffer pH 9) at 55 C for 1h.
zymatic treatment of wool
us w0 rpmpleat tr thein anraturmin.d wa
n Ar+er atere c
conool faGmbd wahe coeposreme. Chemical structures of gallic acid and gallates compounds.
rrent work gallic acid and its alkyl esters with differ-c chain length, such as ethyl (EG), propyl (PG) and (OG)s were tested as laccase substrates for enzymatic mod-ool targeting increased hydrophobicity, and enhancedand antimicrobial properties. The objective was to elu-inuence of the alkyl chain length on the functionalf wool bres.
ls and methods
(EC 18.104.22.168 Trametes sp. laccase, Laccase L603P; 0.125glid; 0.14U/mg protein) was provided by Biocatalysts,
e activity (U) was dened as mol of guaiacol oxi-in at pH 4 and 40 C (max 6400M1 cm1). Methanol,trate, hydrochloric acid, 1-diphenyl-2-picrylhydrazylPH)were purchased from SigmaAldrich. Gallic acidgallate (EG), propyl gallate (PG), octyl gallate (OG),
llate (DG), (chemical structures of all these phenolicin Fig. 1), baird parker agar and egg yolk tellurite emul-
provided by Fluka. Ethanol 96% was purchased fromchemicals used in this work were of the highest grade
etricmeasurementswere performed using aAutolaboChemie) potentiostat/galvanostat controlled by Auto-ftware version 4.9. All the experiments were carriedmL Metrohm cell with a three-electrode congura-orking electrode was a glassy carbon (GCE) with aeter of 3mm (Metrohm). The counter and referenceere platinum (Metrohm) andAg/AgCl (Metrohm) elec-ctively. The renewal of the glassy carbon surface waspolishing with 1.0 and 0.3m alpha-alumina (Microp-
Sambuffer/OG andprevio40 C, 3trol satreated
XPSSystemsourceplaced3d5/20.8 eV.selecte0.8 eV/0.1 eV/mentswith achambysis w
Theed wKruss,distille. Tdrop dmeasuer) on amicrocloth polishing pad (Buehler), followedbyan ultrasonic Selecta bath for 2min. For the experimente a 5l sample of a 0.02gprotein/mL enzyme solutiond onto the polished surface of the GCE and allowed toin at room temperature.
00% wool fabric supplied by Lokateks (Slovenia) wasviously to the enzymatic treatmentwith 1g/L non-ionicotemol NI (Colorcenter, Spain) in liquor to good ratiooratory winch machine (0.1M Na2CO3/NaHCO3 buffer
C for 30min. Thereafter the fabric was bleached at the
The radiwas determdiphenyl-2method, apto test theor hydrogenincubated wroom temped wool wtriplicate anof wool fabric (5 g) were incubated in a 80/20 (v/v, %)solution with 14U/mL laccase and 1mM GA, EG, PG,
according to the optimised procedure described in ourork . The reaction was allowed to proceed for 2h, atm in a laboratory dyingmachineAhiba (Datacolor). Con-s without enzyme and phenolic compound were alsohe above condition.enzymatic treatment the samples were washed exten-80/20 (v/v, %) buffer/EtOH solution for 1h at room
e, then with tap water and with distilled water at 80 CAfter the hot wash every sample were washed in coldter and dried at 50 C for 2h.
transform infrared spectroscopy (FTIR) analysis
ctra of the wool fabrics before and after treatment weresing a Perkin Elmer Paragon 1000 FT-IR spectrometer,100 scans for each spectrum over the 4004000 cm1
pectra were normalised against the peak at 1230 cm1
ing to the amide I group.
hotoelectron spectroscopy (XPS) analysis
eriments were performed in a PHI 5500 Multitechniquem Physical Electronics) with a monochromatic X-rayminium