This study reports for the first time on the enhancement of the bleaching effect achieved on cotton using laccase enzyme. Laccases applied in short‐time batchwise or pad‐dry processes prior to ...conventional peroxide bleaching, improved the end fabric whiteness. The whiteness level reached in the combined enzymatic/peroxide process was comparable to the whiteness in two consecutive peroxide bleaches.
Effect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.
In this work, we studied the influence of the alkyl chain length in enzymatically oxidized gallates on the development of hydrophobicity on paper-based materials, and further correlated the obtained ...effect to the redox mechanism of the enzymatic treatment. Laccase (Lac) enzyme was used to oxidize various members of the gallate homologous series in the presence or not of lignosulfonates (SL) to produce several functionalization solutions (FS), which were subsequently applied to cellulosic substrates. The hydrophobicity of the substrates was then assessed by means of water drop test (WDT) and contact angle (WCA) measurements. Hydrophobicity peaked reaching WDT and WCA values around 5000 s and 130°, respectively, and then decreased with increasing length of the hydrocarbon chain of gallate. Cyclic voltrammetry (CV) was used to study the effect of SL on the redox reactions of several gallates. The intensity of the anodic peak in their voltammograms decreased increasing the chain length of the gallate. The electrochemical behavior of lauryl gallate (LG) differed from that of other gallates. The fact that the voltammetric curves for SL and LG intersected at a potential of 478 mV indicates an enhancing effect of SL on LG oxidation at high potentials (above 478 mV).
A new strain of Trametes hirsuta was found to oxidize various cotton flavonoids. Here we show that laccases of this organism were responsible for oxidation of the flavonoids morin, luteolin, rutin ...and quercetin. Out of two laccases produced by T. hirsuta (60.7 and 51.0 kDa) the more prominent 60.7 kDa laccase was purified and showed K ^sub m^ and k ^sub cat^ values of 75.5, 20.9 and 49.4 μM and 72.5, 96.3 and 32.7 s^sup -1^, hours on ABTS, syringaldazide and DMP, respectively. Pretreatment of cotton with the T. hirsuta laccase resulted in a whiteness increase of 8.5%.PUBLICATION ABSTRACT
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•The valorization of salmon co-streams into cosmetic ingredients is proposed.•An enzymatic treatment was applied to produce anti-ageing and antioxidant biopeptides.•The biopeptides ...were unstable in aqueous medium and prone to microbial contamination.•Stable biopeptide-shell and tea tree oil-core nanospheres were generated.•The nanospheres presented improved antioxidant and antimicrobial properties.
Salmon backbones, co-streams of salmon processing industry, were transformed into stable, odour-free ingredients for cosmetics. First, the backbones were hydrolysed using commercial proteases (Bromelain+Papain, Trypsin, Corolase® 7089 and Protamex®) in order to accomplish the release of fish protein hydrolysates (FPH), which showed antioxidant activity and aptitude to inhibit skin-degrading and inflammatory enzymes. However, due to the FPH instability in aqueous solution and propensity for microbial contamination, their bioactive properties were entirely lost only after 24h. To overcome the low stability and prevent the effect loss, a sonochemical technology was then employed to transform the FPH into stable tea tree oil-filled bioactive peptide-shell nanospheres (NS). Such transformation boosted the FPH antioxidant potential, which was further reflected in protection of fibroblasts from UV damage. In the form of NSs, the FPH resisted microbial contamination for more than 6 months and presented antimicrobial activity against Escherichia coli and Staphylococcus aureus. In addition, the fish odour was eliminated after the NSs processing, thus addressing this important challenge for using fish raw materials in cosmetics. This work suggests an alternative high value use of the fishery co-streams and expands their application potential beyond their current use as fish or animal feed.
Cotton cellulose was dyed "in situ" with a polymeric dye generated by oxidative coupling of colourless 2,5-diaminobenzenesulfonic acid and 1-hydroxyphenol (catechol) with laccase. Up to 70% dye ...fixation was obtained increasing the concentration of catechol less soluble upon oxidation from 1 to 10 mmol, while 1 mmol of diamine was used. Dye fixation was not achieved using equal molar concentrations of the reagents.
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▶ One-step process to produce a multifunctional textile. ▶ Alkyl gallates enzymatic grafting on wool in aqueous–organic medium. ▶ Wool with antibacterial, water repellent as well as ...antioxidant properties. ▶ The length of the alkyl chain of gallates molecule play an important role on wool functionalisation.
The covalent grafting of alkyl gallates on wool through a laccase catalysed reaction in 80/20 (v/v, %) aqueous–ethanol mixture provided in a one-step process a multifunctional textile material with antioxidant, antibacterial and water repellent properties. Gallic acid and its alkyl esters ethyl, propyl, octyl and dodecyl gallate have been enzymatically grafted on wool fibres in order to study the effect of alkyl chain length on wool functional modification. The capacity of laccase to oxidise these phenolic compounds in an aqueous–organic medium has been verified by electrochemical techniques. The increase of CH
2, CH
3 groups in the FTIR spectra, together with the XPS analysis of the enzymatically modified fabrics confirmed the covalent grafting of ester gallates on wool. The result obtained in this work for antibacterial, water repellent as well as antioxidant properties show that the length of the alkyl chain of gallates molecule play an important role on wool functionalisation.
A comparative study of enzyme-mediated indigo reduction is presented as an environmentally-friendly alternative to alkaline sodium dithionite reduction. The effect of the mediator ...1,8-dihydroxy-9,10-anthraquinone in enzymatic reduction was studied by means of voltammetry, both in the presence and absence of different textile materials (polyamide 6, polyamide 6,6 and cotton), and compared to chemically reduced indigo. It was observed that bio-catalytic formation of leuco indigo and its exhaustion on substrates is inversely proportional to the pH within the range of 7–11. Additionally, substrate coloration was strongly influenced by the mediator, resulting in
in situ formation of leuco indigo. This effect was most pronounced for polyamide substrates. The reuse of an enzyme-mediated reduction bath for dyeing was assessed showing that the levelness of the obtained shade was either excellent or good at pH 9 and 11, respectively. The wash, perspiration, and light color fastness properties of all textile materials dyed with enzymatically-reduced indigo were comparable or even better than those obtained with chemically reduced indigo. The use of enzyme-mediated reduction of indigo combined with potential reuse of the reduction bath represents a cost effective and environmentally-friendly dyeing process that can be applied for the dyeing of natural cellulosic and synthetic polyamide fibres.
Wool fibres have been modified with nordihydroguaiaretic acid (NDGA) to improve their performance at use. This water insoluble bi-functional phenolic compound has been grafted on wool through a ...laccase enzyme catalyzed reaction in an aqueous–ethanol mixture. The capacity of laccase to oxidise NDGA in this aqueous–organic medium has been studied electrochemically. The increase of CH
2, CH
3 and aromatic groups signal in the DRIFT spectra, together with SEM images of the enzymatically modified fabrics confirmed the covalent grafting of NDGA on wool. This one step enzymatic process for grafting of NDGA improved the physical and mechanical properties of wool fabrics such as shrink resistance, crease recovery and tensile strength. Furthermore, the NDGA imparted to the textile material strong antioxidant activity and UV protection.
Three thermoalkaliphilic bacteria, which were grown at pH 9.3–10 and 60–65
°C were isolated out of a textile wastewater drain. The unknown micro-organisms were identified as thermoalkaliphilic
...Bacillus sp. Growth conditions were studied and catalase activities and stabilities compared. Catalases from
Bacillus SF showed high stabilities at 60
°C and pH 9 (
t
1/2=38 h) and thus this strain was chosen for further investigations, such as electron microscopy, immobilization of catalase and hydrogen peroxide degradation studies. Degradation of hydrogen peroxide with an immobilized catalase from
Bacillus SF enabled the reuse of the water for the dyeing process. In contrast, application of the free enzyme for treatment of bleaching effluents, caused interaction between the denaturated protein and the dye, resulting in reduced dye uptake, and a higher color difference of 1.3
Δ
E* of dyed fabrics compared to 0.9
Δ
E* when using the immobilized enzyme.
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