Nano-SiO2in-situ hybrid polyurethane leather coating with enhanced breathability

A novel in-situ nano hybrid technique combined with industrialized wet phase inversion coating-forming process was developed for the modification of polyurethane (PU) leather coating with nano-SiO₂. During the wet phase inversion process, nano-SiO₂ particles were in-situ generated synchronously as polyurethane resin coagulated. Scanning electron microscope analysis indicated that when the SiO₂ concentration was limited within 1.5 wt%, the size scale of in-situ generated nano-SiO₂ ranged from 70 to 150 nm, which were well-separated and dispersed uniformly throughout the PU coating. After nano hybridization, extra mesopores were detected in the PU coating by nitrogen adsorption/desorption experiment. These mesopores were correlated with enhanced water vapor and gas (hydrogen, nitrogen, and oxygen) permeability, which could improve the breathability or wear comfort of PU leather. In spite of extra mesopores, the hybrid PU coating maintained comparable hydrostatic pressure to control. Nevertheless, when the SiO₂ concentration was increased up to more than 1.5 wt%, micro-SiO₂ particles and agglomerates dominated throughout the PU coating, which obstructed mass transportation and lowered the breathability of the coating. Without disturbing established wet phase inversion coating-forming process in PU leather industry, the novel in-situ nano hybrid technique developed in this study may be of great potential for producing PU leather with improved breathability on an industrial scale.     

Electrospun in-situ hybrid polyurethane/nano-TiO<Subscript>2</Subscript> as wound dressings

By combining the organic-inorganic hybridization, wet phase inversion, and electrospinning, novel electrospun polyurethane (PU) membranes with in-situ generated nano-TiO₂ were prepared, which satisfied the requirements of an ideal wound dressing. The morphology of the PU-TiO₂ mats and the cross sectional morphologies of the membranes were characterized by a scanning electron microscopy (SEM). The average diameter of the individual fibers obtained from the solutions was 341±12 nm. SEM micrographs with higher magnification further showed that the in-situ generated TiO₂ particles were well-separated and dispersed homogeneously in the membranes. The average sizes of TiO₂ particles were increased from 31 to 57 nm, with the increase of nano-TiO₂ concentration. The water vapor transmission rates (WVTRs) of the membranes were in the range of 373.55–3121.86 g/m²·d and decreased gradually with the increase of nano-TiO₂ concentration. The water absorption of various PU membranes was in the range of 210.90–397.98 % which was enough to prevent wound beds from exudate accumulation. Shake flask testing indicated that the PU membrane exhibited antibacterial efficiency against Pseudomonas aeruginosa (Ps. aeruginosa) and Staphylococcus aureus (S. aureus) due to in-situ generated of nano-TiO₂. These electrospun nanofibrous membranes also had no toxic effect and showed good and immediate adherence to L929 cells.     

Photocatalytic degradation of formaldehyde by silk mask paper loading nanometer titanium dioxide

Silk mask paper with different adsorbability was prepared by changing the beating degree of silk pulp and the basis weight of silk paper, and photocatalytic silk mask paper was prepared by loading nanometer titanium dioxide (nano-TiO₂) on the silk mask paper, then degradation of formaldehyde by silk mask paper loading nano-TiO₂ under daylight lamps and ultraviolet lamps were investigated, respectively. Results showed that silk mask paper could adsorb formaldehyde and had higher adsorption efficiency in the initial stage, and the adsorption/desorption equilibrium could be basically achieved in 60 minutes. The adsorption capacity of silk mask paper made from silk pulp with beating degree of 45 ^oSR was relatively low, and it increased with the increase of beating degree, but there was little change in adsorption when the beating degree of silk pulp exceeded 65 ^oSR. Under daylight lamps, 26.61 %, 31.42 % and 38.21 % of formaldehyde could be degraded in 180 minutes by silk mask paper loading 1 wt%, 3 wt% and 5 wt% nano-TiO₂, respectively. However, under ultraviolet (UV) lamps, 46.23 %, 55.47 % and 66.38 % of formaldehyde could be degraded within the same time, respectively. More formaldehyde could be degraded by photocatalytic silk mask paper under UV lamps than under daylight lamps, and the more the load of nano-TiO₂ on the silk mask paper, the higher the degradation rate of formaldehyde within the same time.     

Azocalix[4]pyrrole dyes: Application in dyeing of fibers and their antimicrobial activity

The dyeing performance of the azocalix[4]pyrrole dyes on fibers like nylon, wool, acrylic, and silk have been determined. Their fastness properties towards light, water, washing, and acid-alkali perspiration have been studied. The position of color in CIELAB coordinates (L*, a*, b*, H, and C*) was assessed. The azocalix[4]pyrrole demonstrated good antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Aspergillus niger. These super molecules exhibit bright shades on fabric with very good fastness properties.     

Synthesis of non-water soluble polymeric guanidine derivatives and application in preparation of antimicrobial regenerated cellulose

In order to prepare antimicrobial regenerated cellulose fibers from blended spinning solutions, three non-water soluble polymeric guanidine derivatives, polyhexamethylene guanidine dodecyl benzene sulfonate (PHGDBS), polyhexamethylene guanidine dodecyl sulfate (PHGDSA), and polyhexamethylene guanidine laurylsulfonate (PHGLSO) were synthesized. And the chemical structure of these agents was verified by element analysis, Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (¹H-NMR). The antimicrobial activity of the three agents as well as cellulose films containing PHGDBS was also studied. The results showed that the compounds we prepared had strong properties against both bacterial and fungus, including Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Candida albicans, and Aspergillus niger. Moreover, it was found that three antimicrobial agents were insoluble in water but they can dissolve in solvents of cellulose such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and N-methylmorpholine-N-oxide monohydrate (NMMO·H₂O). Meanwhile, it was also proved that [BMIM]Cl had little effect on the antimicrobial properties of these agents. The cellulose films containing only 1.0 wt% PHGDBS showed 99.94 % and 96.95 % bacterial reduction rates for S. aureus and E. coli, respectively. Moreover, still over 91 % of bacterial reduction was maintained after 15 laundering cycles. It suggests that the three agents will be suitable to prepare antimicrobial regenerated cellulose fibers or films.     

Structure and performance of<Emphasis Type="Italic">Bombyx mori</Emphasis> silk modified with nano-TiO<Subscript>2</Subscript> and chitosan

Bombyx mori (B. mori) silk was modified with the nano-TiO₂ and chitosan dispersion system by the crosslinking reactions of citric acid (CA) and maleic anhydride (MA). The average size of the nano-TiO₂ particles in the aqueous dispersion system was 36.7 nm. The scanning electron microscopy (SEM) micrographs showed that the nano-TiO₂ particles were spherical and homogeneously dispersed in the dispersion system, and the surface ofB. mori silk fiber treated with the nano-TiO₂ and chitosan dispersion system was rougher than that of the untreated one. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) Spectrometry indicated that the crystallinity of theB. mori silk fiber increased after treatment. It was also found that the nano-TiO₂ and chitosan contributed to significantly enhance the mechanical properties including breaking strength, breaking elongation, initial modulus, rupture work, and elastic recovery property of theB. mori silk fiber. The wrinkle-resistant performance of the treatedB. mori silk fabrics was also greatly improved.     

Preparation and properties of Nano-TiO2 photo-catalytic silk respirator paper

In order to obtain paper respirator with dust resistance performance and antibacterial property, silk photo-catalytic respirator paper was made by loading nano-TiO₂ photo-catalyst on silk based respirator paper. The pore structure, surface topography and TiO₂ distribution, and the filtration performance of silk respirator paper were studied by using a pore size meter (PSM), a field emission scanning electron microscope (FESEM), and a filter tester, respectively. In addition, the antibacterial property of silk respirator paper was also investigated. The results showed that the pore structure and filtration performance of silk respirator paper could be controlled by changing the degree of beating of silk pulp and the basis weight of silk paper. Silk respirator paper of 45 g/m² made from silk pulp having beating degree of 85 ^oSR had high filtration efficiency and appropriate filtration resistance. Nano-TiO₂ particles were mainly attached to the surface of silk paper, and the loading of nano-TiO₂ photo-catalyst resulted in a slight decrease in filtration resistance and filtration efficiency of silk respirator paper. It, however, improved the antibacterial property of silk respirator paper effectively.     

Development of UV Protective,Superhydrophobic and Antibacterial Textiles Using ZnO and TiO<Subscript>2</Subscript> Nanoparticles

In this research work, multifunctional cotton fabric comprising of UV protection, superhydrophobicity and antibacterial activity has been developed using facile pad-dry-cure method. In the first step, the concentration of repellent chemical has been optimized. Then, formulations containing nanoparticles of ZnO or TiO₂ along with optimized concentration of repellent chemical and organic-inorganic binder have been applied to cotton fabric followed by the evaluation of functional properties. The surface morphology and elemental composition of treated fabric has been characterized through SEM and EDX, respectively. The treated samples have shown promising UV protection, superhydrophobicity and antibacterial properties durable upto 20 washing cycles.     

Preparation of collagen fiber/CaCO3 hybrid materials and their applications in synthetic paper

The collagen fiber/CaCO₃ hybrid materials were successfully prepared via in situ organic-inorganic hybrid technique. The surface morphology, hybrid mechanism, thermal and hydrothermal stability of these materials were investigated, respectively. Scanning electron microscopy (SEM) analysis showed that the size scale and distribution of CaCO₃ particles in collagen fiber relied on the concentration of CaCl₂. When the CaCl₂ was at low concentration, for example 6 wt%, the in-situ produced CaCO₃ particles were distributed evenly around the collagen fiber, the particle size could be controlled in the range of 2–4 µm and no apparent coagulation of CaCO₃ particles was found. Fourier transform infrared spectroscopy (FTIR) study revealed the interactions between the collagen fiber and CaCO₃ particles. The water solubility test and TGA analysis indicated that the solubility of collagen fiber in hot water decreased significantly after hybridization with CaCO₃ particles, whereas, the decomposition temperature was improved with increasing of the production of CaCO₃ particles. Moreover, the hybrid materials were used in conjunction with polyurethane and CaCO₃ powder to fabricate a novel synthetic paper. The result showed that the synthetic paper had good writing and printing.     

Effect of concentration of titanium dioxide acting as catalyst or co-catalyst on the wrinkle-resistant finishing of cotton fabric

The wrinkle-resistant property of cotton specimens treated by 1,2,3,4-butanetetracarboxylic acid (BTCA) and catalysed by sodium hypophosphite (SHP) in the presence of TiO₂ or nano-TiO₂ has been evaluated in the present study. In this study, Scanning Electron Microscopy proved the presence of TiO₂ or nano-TiO₂ on the fibre surface. It was also found that 0.1–0.2 % TiO₂ or nano-TiO₂ was the optimum concentration to enhance the wrinkle-resistance of BTCA-SHP-treated cotton fabrics. In addition, the TiO₂ or nano-TiO₂ added in the wrinkle-resistant treatment could act as a multi-functional finishing agent to improve the UV protection property while they are safe to human skin as proved by the cytotoxicity test. Therefore, TiO₂ or nano-TiO₂ was evident that they could enhance the finishing performance and minimise the side effect.     

Nutritional profile and antimicrobial spectrum of the spiceAframomum danielli K. Schum

The spice,Aframomum danielli, on a wet weight basis with a moisture content of 10.5%, protein content of 8.2% (dry matter basis) and caloric value of 469.7 kcal/100 g, contains in varying amounts, minerals like calcium, magnesium, sodium, manganese, phosphorus, zinc and copper. Amino acids found in varying concentrations inA. danielli include L-Threonine, L-Serine, L-Valine, L-Proline, L-Glutamic acid, glycine, L-Leucine and L-Lysine. Using minimum inhibition zone of 20–22 mm in diameter,A. danielli inhibited the growth ofSalmonella enteriditis, Psudomonas fragi, Pseudomonas fluorescens, Proteus vulgaris, Streptococcus pyogenes, Staphylococcus aureus, Aspergillus flavus, A. parasiticus, A. ochraceus andA. niger. The minimum concentration (MIC) determined forKlebsiella pneumoniae andPseudomonas aeruginosa was 1 in 320 whilst the MIC forS. aureus was 1 in 8,000.     

Eco-dyeing and antimicrobial properties of chlorophyllin copper complex extracted from Sasa veitchii

Cotton fabrics were dyed with the natural chlorophyll derivates (chlorophyllin, Chlin) after treatment with and without chitosan. The water-soluble Chlin extracted from Sasa veitchii based on Japanese bamboo leaves were investigated in order to improve the textile coloration and antimicrobial activity. The antimicrobial activity of the dyed fabrics that had been pretreated with chitosan as a biomordant over a concentration range of 0∼0.7 % was tested against two common gram pathogens: Staphylococcus aureus and Klebsiella pneumoniae. The color depth as measured by the K/S value, the color difference and the colorfastness to washing and light were also evaluated. The fabrics treated with chitosan resulted in an increase in dye uptake in all cases compared with the corresponding untreated fabrics, and did not affect fastness of washing and light. The cotton fabrics dyed with mordant and CuSO₄ extracts appeared to have over 99.9 % of antimicrobial activity, while MeOH extracts showed 71.8 %.     

Discovery of Anti-MRSA Secondary Metabolites from a Marine-Derived Fungus Aspergillus fumigatus

Methicillin-resistant Staphylococcus aureus (MRSA), a WHO high-priority pathogen that can cause great harm to living beings, is a primary cause of death from antibiotic-resistant infections. In the present study, six new compounds, including fumindoline A–C (1–3), 12β, 13β-hydroxy-asperfumigatin (4), 2-epi-tryptoquivaline F (17) and penibenzophenone E (37), and thirty-nine known ones were isolated from the marine-derived fungus Aspergillus fumigatus H22. The structures and the absolute configurations of the new compounds were unambiguously assigned by spectroscopic data, mass spectrometry (MS), electronic circular dichroism (ECD) spectroscopic analyses, quantum NMR and ECD calculations, and chemical derivatizations. Bioactivity screening indicated that nearly half of the compounds exhibit antibacterial activity, especially compounds 8 and 11, and 33–38 showed excellent antimicrobial activities against MRSA, with minimum inhibitory concentration (MIC) values ranging from 1.25 to 2.5 μM. In addition, compound 8 showed moderate inhibitory activity against Mycobacterium bovis (MIC: 25 μM), compound 10 showed moderate inhibitory activity against Candida albicans (MIC: 50 μM), and compound 13 showed strong inhibitory activity against the hatching of a Caenorhabditis elegans egg (IC₅₀: 2.5 μM).     

Development of nanofibrous membranes with far-infrared radiation and their antimicrobial properties

This study investigated the incorporation of nanoscale germanium (Ge) and silicon dioxide (SiO₂) particles into poly(vinyl alcohol) (PVA) nanofibers with the aim of developing nanostructures with far-infrared radiation effects and antimicrobial properties for biomedical applications. Composite fibers containing Ge and SiO₂ were fabricated at various concentrations of Ge and/or SiO₂ using electrospinning and layered on polypropylene nonwoven. The morphological properties of the nanocomposite fibers were characterized using a field-emission scanning electron microscope and a transmission electron microscope. The far-infrared emissivity and emissive power of the nanocomposite fibers were examined in the wavelength range of 5-20 μm at 37 °C. The antibacterial properties were quantitatively assessed by measuring the bacterial reductions of Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. Multi-component composite fibers electrospun from 11 wt% PVA solutions containing 0.5 wt% Ge and 1 wt% SiO₂ nanoparticles exhibited a far-infrared emissivity of 0.891 and an emissive power of 3.44·102 W m^?2 with a web area density of 5.55 g m^?2. The same system exhibited a 99.9 % bacterial reduction against both Staphylococcus aureus and Escherichia coli, and showed a 34.8 % reduction of Klebsiella pneumoniae. These results demonstrate that PVA nanofibrous membranes containing Ge and SiO₂ have potential in medical and healthcare applications such as wound healing dressings, skin care masks, and medical textile products.     

Hydrothermal Processing of Barley (cv. Blenheim): Optimisation of Phytate Degradation and Increase of FreeMyo-inositol

Optimal conditions were developed for hydrothermal processing of whole barley kernels (cv. Blenheim) to degrade phytate (myo-inositol hexaphosphate) and to increase the content of freemyo-inositol. The hydrothermal treatment comprised of two wet steeps, where lactic acid solution of different concentrations was used, and two dry steeps followed by successive drying. Experiments were performed as a central composite design and evaluated by multiple linear regression. The variables in the experiments were temperature in the first wet and dry steep (T₁), temperature in the second wet and dry steep (T₂) and lactic acid solution concentration in both wet steeps (C) and mathematical models were developed in these variables. Optimal conditions for maximal phytate degradation and for maximal increase of freemyo-inositol wereT₁=48 °C,T₂=48–50 °C andC=0·8%, at these conditions the amount of phytate was reduced by 95–96% and the freemyo-inositol concentration was increased from 0·56 to 2·45 μmol/g d.m. We conclude that this hydrothermal process can be used to produce a barley product (cv. Blenheim) with a low phytate content and a high level of freemyo-inositol.     

Multifunctional modification of wool fabric using graphene/TiO<Subscript>2</Subscript> nanocomposite

In this study, a new finishing technique is introduced through treatment of wool fabric with graphene/TiO₂ nanocomposite. Graphene oxide/titanium dioxide nanocomposite first applied on the wool fabric by hydrolysis of titanium isopropoxide in graphene oxide suspension and then this coating chemically converted by sodium hydrosulfite to graphene/TiO₂ nanocomposite. The homogenous distribution of the graphene/TiO₂ nanocomposite on the fiber surface was confirmed by field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS) and X-ray mapping. X-ray diffraction patterns proved the presence of titanium dioxide nanoparticles with a crystal size of 127 Å on the treated wool fabric. Also, the defect analysis based on X-ray photoelectron spectroscopy (XPS) established the composition of the nanocomposite. Other characteristics of treated fabrics such as antibacterial activity, photo-catalytic self-cleaning, electrical resistivity, ultraviolet (UV) blocking activity and cytotoxicity were also assessed. The treated wool fabrics possess significant antibacterial activity and photo-catalytic self-cleaning property by degradation of methylene blue under sunlight irradiation. Moreover, this process has no negative effect on cytotoxicity of the treated fabric even reduces electrical resistivity and improves UV blocking activity.     

Preparation and properties of 2-(2-aminoethoxy) ethyl chitosan/cellulose fiber using N-methylmorpholine-N-oxide process

N-methylmorpholine-N-oxide (NMMO) is used widely in the manufacturing of man-made cellulose fibers and functional lyocell fibers due to its environment-friendly advantage. Although chitosan is known as a natural antibacterial polymer it has poor solubility in neutral to basic medium and the antibacterial activity is shown only in acidic medium. Chitosan’s poor solubility in NMMO is the disadvantage for the production of antibacterial lyocell fibers. This paper investigates a more “NMMO soluble” derivative of chitosan, 2-(2-aminoethoxy) ethyl chitosan (AECS). AECS has greatly improved solubility in NMMO hydrate, and stronger antibacterial activity than chitosan. AECS was introduced to modify the lyocell fiber spun in a co-solution of cellulose and AECS in NMMO hydrate. The physical properties and antibacterial activity of the fibers were examined and the results indicated that the modified lyocell fiber, containing more than 2 wt% of AECS, exhibits good antibacterial activity against E. coli and slightly decreased tensile strength compared with unmodified fibers.     

Modification and Characterization of Nano-TiO<Subscript>2</Subscript> for Efficient Fixation on Cotton Fibers

In this paper, a silane coupling agent, 3-aminopropyltriethoxysilane, was reacted with nano-TiO₂ to introduce amino group onto it which was then reacted with trichlorotriazine to obtain a dichlorotriazine functionalized nano-TiO₂ for the firm fixation of it on cotton fibers. The reaction process was monitored by the titration of primary and secondary amino groups, and the reaction conditions were optimized with orthogonal method accordingly. The dichlorotriazine functionalized nano-TiO₂ was reacted with cotton fabric by the nucleophile substitution reaction to afford nano-TiO₂ functionalized cotton fabric, the structure and surface morphology of the nano-TiO₂ finished cotton fibers were studied by FT-TR and SEM. In addition, the fixation duration of the nano-TiO₂ modified cotton was studied according to AATCC test method 61–2010. The results show that the washing fastness of the nano-TiO₂ is excellent.     

Affinity Chromatography with Immobilised Endoxylanases Separates TAXI- and XIP-type Endoxylanase Inhibitors from Wheat (Triticum aestivum L.)

An affinity-based purification procedure allowed the resolution of two distinct groups of endoxylanase inhibitors with different molecular structures and endoxylanase specificities from wheat wholemeal. The first group comprises the so-called Triticum aestivum L. Endoxylanase inhibitor (TAXI)-type proteins which are of approx. M_r 40 000 and occur in two different molecular forms. These inhibitors were removed from a concentrated cation exchange chromatography fraction from wheat wholemeal on a Bacillus subtilis endoxylanase affinity column. The second group of structurally different endoxylanase inhibitors, the so-called xylanase inhibiting protein (XIP)-type, of approx.M_r 29 000–32 000, with pI values varying between 8·8 and 9·2, was purified from the unbound fraction from the B. subtilis endoxylanase affinity column by chromatography on an Aspergillus niger endoxylanase affinity column followed by gel permeation chromatography. The XIP-type inhibitors are not active against the B. subtilis endoxylanase and were consequently not retained on the B. subtilis endoxylanase column. Further analysis of the XIP-type proteins by high-resolution cation exchange chromatography, SDS-PAGE and iso-electrofocusing, revealed several forms. They had similar endoxylanase specificities and N-terminal amino acid sequences.     

Preparation of Polyurethane Silicon Oxide Nanomaterials as a Binder in Leather Finishing

Leather finishing processes using toxic organic solvent based produce volatile organic compounds (VOC), chronic exposure to this chemicals effect on workers' health causing many diseases especially lung cancer. So, polyurethane waterbased was synthesized for application in leather finishing instead of organic solvent based because it’s economic and safety for industry and workers. Preparation of water-based polyurethane (PU) depends on the reaction of polyethylene glycol (PEG, 300) with isophorone diisocyanate (IPDI) and the reaction of IPDI-1,4-butanediol (BDO) together with dimethylolpropionic acid (DMPA), was synthesized by poly-addition polymerization reaction. PU was then modified with different amounts of silicon dioxide nanoparticles (1-5 % SiO₂), used as a binder in leather finishing. Leather coated was characterized physically, chemically and thermally by FTIR, GPC, DLS, TEM, SEM and TGA. The results revel that, water vapor permeability (WVP) of leather coated with PU modified with SiO₂ showed improvement due to the existence of SiO₂ particles which increases the interspaces of the polyurethane coating. SEM showed that when the amount of SiO₂ nanoparticles increases, there is uniform nanoparticles accumulated can be observed. EDX prove the presence of Si and O₂ elements and the formation of SiO₂ nanoparticles. Mechanical properties discussed that tensile strength; tear strength and elongation at break % increase with increase SiO₂ concentration until 3 % SiO₂ nanoparticles. TGA showed an improvement of thermal stability of coated leather modified with SiO₂. Therefore, this study succeeded in preparation of safe, ecofriendly of water-based polyurethane binders which modified with SiO₂ for using in leather finishing.