Reversible bacteria-killing and bacteria-releasing cotton fabric with anti-bacteria adhesion ability for potential sustainable protective clothing applications.

Multifunctional antibacterial surfaces are playing an essential role in various areas. Smart antibacterial materials equipped with switchable "bacteria-killing" and "bacteria-releasing" abilities have been created by scientists. However, most of them are either biologically incompatible, or complex fabricating procedures, or cannot prevent themselves from being attached by bacteria. In this work, a double-layer smart antibacterial surface was created easily by simple surface initiate atom transfer radical polymerization: the upper layer PSBMA provides anti-bacteria adhesion capacity, the NCl bond can show bacteria-killing ability and the under layer PNIPAM can exhibit bacteria-releasing property. Remarkably, the NCl bond can interconvert with the NH bond easily, which allows switching between bacteria-killing and bacteria-releasing. As a result, the functional cotton fabrics can resist about 99.66 % of bacteria attaching, kill nearly 100 % of attached bacteria after 5 min contacting and release about 99.02 % of the formerly attached bacteria. Furthermore, the functional cotton fabric kept excellent anti-bacteria adhesion ability (about 99.27 %) and bacteria-releasing capacity (about 98.30 %) after 9 cycles of re-chlorination. In general, a reversible "bacteria-killing" and "bacteria-releasing" cotton fabric was fabricated with well anti-bacteria adhesion capacity in a simple way, and this smart multifunctional cotton fabric shows a great potential application in reusable protective clothing.

Plasticizer phthalate esters degradation with a laccase from Trametes versicolor: effects of TEMPO used as a mediator and estrogenic activity removal.

Phthalate esters (PAEs) are toxic and persistent chemicals that are ubiquitous in the environment and have attracted worldwide attention due to their threats to the environment and human health. Dimethyl phthalate (DMP) is a relatively simple structure and one of the most observed PAEs in the environment. This study investigated the degradation of the DMP using Trametes versicolor laccase and its laccase-mediator systems. The degradation effect of laccase alone on DMP was poor, while the laccase-mediator systems can effectively enhance the degradation efficiency. Within 24 h, 45% of DMP (25 mg/L) was degraded in the presence of 0.8 U/mL laccase and 0.053 mM 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO). A certain concentration (1 mM) of metal ions Al3+, Cu2+ or Ca2+ can positively promote DMP degradation with the laccase-TEMPO system. Moreover, the structure of PAEs also had a great influence on the degradation efficiency. Higher degradation efficiencies were observed when incubating PAEs with short alkyl side chains by the laccase-TEMPO system compared to that with long alkyl side chains. Additionally, the branched-chain PAEs had a better degradation effect than the straight-chain. The estrogenic activity of the DMP solution after reaction was much smaller than that of the original solution. Finally, transformation products ortho-hydroxylated DMP and phthalic acid were identified by GC-MS and the possible degradation pathway was proposed. This study verifies the feasibility of the laccase-TEMPO system to degrade PAEs and provides a reference for exploring more potential value of laccase.

Effects of exogenous proteins on enzyme desizing of starch and its mechanism.

Added protein to starch has abundantly applied to size the yarns. However, scarce information is available about the impact of proteins on the enzyme desizing of starch. Thus, the objective of this study was to explore the effect of corn gluten, soybean protein and bone glue on enzyme desizing and reveal the interference mechanism. The desizing efficiency of starch was detected after added proteins. The contact angle, swelling ability, protein content and structure of starch adhesion on desized yarn were measured to analyze the effect of protein on desizing. In addition, the binding forces between protein and starch were detected, and the inhibition mechanism was analyzed. Experimental results showed that desizing efficiencies of starch were decreased after adding the protein. Corn gluten had the strongest influence in hindering desizing due to the weakest promotion in the swelling of film and the stronger binding force between protein and starch, mainly through hydrophobic interaction and hydrogen bond. Improving the swelling ability of film and inhibiting the binding between starch and protein may be feasible ways to reduce the inhibition of protein on desizing.

Study on the cross-linking process of carboxylated polyaldehyde sucrose as an anti-wrinkle finishing agent for cotton fabric.

Sucrose was oxidized in a two-step oxidation reaction catalyzed by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase and sodium periodate (NaIO4). To generate carboxylated polyaldehyde sucrose (openSu) containing multiple aldehyde and carboxyl groups. The amount of TEMPO and laccase used, as well as the temperature and reaction time were optimized for the oxidation reaction. The successful combination of aldehyde and carboxyl groups of openSu with cellulose was achieved by changing the composition, ratio of the catalyst and the curing conditions. Thereafter, we analyzed the structural characteristics of openSu as well as the aldehyde and carboxyl group content using nuclear magnetic resonance carbon spectroscopy (13C NMR). We found that the optimal finishing conditions were a mixture of magnesium chloride and sodium hypophosphite at a mass concentration ratio of 16 g/L:4 g/L, and curing at 150 °C for 3 min followed by curing at 180 °C for 2 min. There was significant improvement in the anti-wrinkle performance of the openSu-finished fabric, with a wrinkle recovery angle of 258°, whiteness index of 72.1, and a tensile strength rate of more than 65%. We also studied the covalent crosslinking mechanism between openSu and the cotton fabrics.

Degradation of octylphenol polyethoxylates with a long ethoxylate chain using the laccase-mediated systems.

Alkylphenol polyethoxylates (APEOn) are the second-largest category of commercial nonionic surfactants, which are difficult to degrade naturally in the environment. This study examined the degradation of octylphenol polyethoxylate (OPEOn) by laccase and its laccase-mediated systems. The results showed that OPEOn was poorly degraded by laccase alone. 2, 2'-azino-bis [3-ethylbenzothiazoline-6-sulphonic acid] (ABTS), 1-hydroxybenzotriazole (HBT), and 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) were selected as the redox mediators. Experimental results also indicated that 52.4% of the initial OPEOn amount was degraded by laccase in the presence of TEMPO. The degradation efficiency was analyzed using high-performance liquid chromatography. Furthermore, the structural characteristics of the degradation products were measured using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and nuclear magnetic resonance spectroscopy, and it could be found that the laccase-TEMPO system could gradually shorten the ethoxylate chain by oxidizing the primary hydroxyl group of OPEOn, thereby degrading the OPEOn of the macromolecule into small molecules. The maximum of the ion peak distributions of OPEOn decreased from n = 8 finally down to 3. The novel enzymatic system introduced by this study will become a promising alternative method for high-efficiency APEOn conversion and had great potential value in wastewater treatment.

Oxysucrose polyaldehyde: A new hydrophilic crosslinking reagent for anti-crease finishing of cotton fabrics.

For the first time, oxidized sucrose (oxysucrose) was used as a hydrophilic crosslinking reagent instead of conventional anti-crease reagents for cotton fabrics. In this research, the partial oxidization of sucrose with sodium periodate generated multiple aldehydes, which acted as multifunctional cross-linkers and endowed cotton fabrics with anti-crease and hydrophilic function. The results showed that the oxysucrose-treated cotton fabrics obtained the maximum crease recovery angle of 245°, durable press rating of 3.0, and whiteness index of 82.8. Importantly, the oxysucrose-treated samples showed better hydrophilicity that overcomes the hydrophobization deficiency of anti-creased cotton fabrics treated with previously reported dimethylol dihydroxy ethylene urea (DMDHEU), glutaraldehyde (GA), and 1, 2, 3, 4,-butanetetracarboxylic acid (BTCA). The etherification reaction between the aldehyde group of oxysucrose and the hydroxyl group of cellulose was investigated and the possible crosslinking and anti-crease mechanism was proposed.