Thrombin immobilization to enzymatic modified PET and PAN fabrics and their applications

Enzymatic modification of synthetic materials has immense potential both of the functionalization of polymeric materials, such as poly(acrylonitrile) or polyesters, and the production of polymers for special applications, such as medical devices and enzyme immobilization. In this study, poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics were modified with commercial laccase and nitrilase, respectively. Contact angles of enzymatic modified and unmodified fabrics were measured and it was found contact angles of enzymatic modified fabrics were less than those of unmodified fabrics. Attenuated-Total-Reflection-Fourier-Transform infrared spectroscopy showed that carboxylic acid groups occurred on fabrics after enzymatic modifications. Surfaces of modified and unmodified fabrics were investigated using scanning electron microscopy. Surfaces of unmodified fabrics were smooth but surfaces of modified fabrics were rugged and cracked. Thrombin was immobilized in modified fabrics by using 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide. Optimization studies were also performed for the immobilization of thrombin. After prepared material was tested to stop bleeding in vitro conditions and it was found that thrombin immobilized poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics had a reduced recalcification time to 51 % and 89 %, respectively. Thrombin immobilized poly(ethyleneterephtalate) fabric was also tested in in vivo conditions by using Cavia porcellus and it was observed that this material caused bleeding to stop at a ratio of 24.6 %. The results were statistically significant.     

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.     

Nano immobilization of enzyme to improvement of biofuel cell electrode's function

This study centers on development of the enzyme presentation as a cathode catalyst. Laccase enzyme is immobilized at nano meter scale in quaternary ammonium bromide salt treated Nafion polymers and assorted with high surface area carbon powders that are then deposited onto a solid support to create the cathode electrode. Optimization of the synthesis circumstances resulted in notably enhanced performance toward oxygen reduction reaction.     

脲酶抑制剂在棉花上的应用效果探讨

1997年在石门县利用湘棉10号进行了脲酶抑制剂--氢醌(HQ)对棉花产量和效益影响的研究.结果表明,氢醌能提高棉花对尿素氮的利用率,在施氮水平适宜的条件下,按尿素用量的5%加入氢醌.可以提高皮棉产量和获得较高的经济效益.     

天然抗氧化剂对α-亚麻酸的抗氧化效果研究

采用Schaal烘箱法和加速氧化法，分别考察了不同纯度、不同添加量的天然VE、茶多酚、鞣花酸、竹叶黄酮等天然抗氧化剂对α-亚麻酸乙酯的抗氧化效果。分析两种方法的结果，可以得出几种天然抗氧化剂对α-亚麻酸乙酯抗氧化效果的顺序为：90%茶多酚>82%鞣花酸>50%茶多酚>竹叶黄酮，在添加量为0.05%时对α-亚麻酸乙酯的抗氧化效果最好；加速氧化法较Schaal烘箱法更直观、快速简便，试剂损耗小。     

Preparation and characterization of aminobenzyl cellulose by two step synthesis from native cellulose

Synthesis and structural characterizations of nitro- and aminobenzyl cellulose were carried out. Cellulose derivatives were synthesized by etherification. Nitrobenzylation produced 80 % yield by treating a mixture of microcrystalline cellulose, 4-dimethyl aminopyridine, and 4-nitrobenzyl chloride at 80 °C for 10 h. Nitrobenzyl cellulose was then reduced to aminobenzyl cellulose with 93 % yield using indium metal in ethanol and saturated aqueous ammonium chloride. In addition to their structural characterizations by FT-IR and ¹³C CP/MAS NMR, TGA will also be described. These reactions serve as models for future cotton fiber finishing technology with applications in flame resistance.     

Thrombin immobilization to Poly(Methacrylicacid) graft polymerized PET and PAN fabrics

Poly(ethylene terephthalate) and poly(acrylonitrile) fabrics are the most produced synthetic fabrics in the world. Their production and usage increase at medical textile. There is no functional group in their structure for enzyme immobilization. Hence, they are not inclined to react. However, functional groups could be added to their structure using graft polymerization. In this study, methacrylic acid was graft polymerized to poly(ethylene terephthalate) and poly(acylonitrile) fabrics. Characterization of modified fabrics was carried out and thrombin was immobilized to poly(methacrylic acid) graft polymerized poly(ethylene terephthalate) and poly(acylonitrile) fabrics using 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide. Optimization studies were also performed for the immobilization of thrombin. Thrombin immobilized poly(methacrylic acid) graft polymerized poly(ethylene terephtalate) and poly(acrylonitrile) fabrics were reduced recalcification time 30 % and 25 %, respectively. It is the first time, an enzyme was immobilized to fabric and its in vitro applications were performed. Thrombin has not been immobilized to synthetic fabric, yet.     

On use of cellulose nanowhisker to enhance the physical properties of electrospun biopolyurethane

This research focused on the improvement of the physical properties of biopolyurethane (BPU) using cellulose nanowhisker (CNW). For the study, BPU was synthesized by one-shot polymerization from corn sugar-based polyol and methylene diiscocyanate (MDI). CNW was prepared via conventional acid hydrolysis of pulp using sulfuric acid. The synthesized BPU was mixed with the CNW and then electrospun. The addition of CNW improved simultaneously the hydrophilicity and the mechanical properties of BPU. The improved properties will give more opportunity to BPU for medical applications.     

Cationized albumin-biocoatings for the immobilization of lipid vesicles

Tethered lipid membranes or immobilized lipid vesicles are frequently used as biomimetic systems. In this article, the authors presented a suitable method for efficient immobilization of lipid vesicles onto a broad range of surfaces, enabling analysis by quantitative methods even under rigid, mechanical conditions-bare surfaces such as hydrophilic glass surfaces as well as hydrophobic polymer slides or metal surfaces such as gold. The immobilization of vesicles was based on the electrostatic interaction of zwitterionic or negatively charged lipid vesicles with two types of cationic chemically modified bovine serum albumin (cBSA) blood plasma proteins (cBSA-113 and cBSA-147). Quantitative analysis of protein adsorption was performed as the cBSA coatings were characterized by atomic force microscopy, surface zeta potential measurement, fluorescence microscopy, and surface plasmon spectroscopy, revealing a maximal surface coverage 270-280?ng/cm(2) for 0.02 mg/ml cBSA on gold. Small unilamellar vesicles as well as giant unilamellar vesicles (GUVs) were readily immobilized (～15?min) on cBSA coated surfaces. GUVs with 5-10 mol% negatively charged 1,2,-dipalmitoyl-sn-glycero-3-phosphoglycerol remained stable in liquid for at least 5 weeks.     

Sericin-fixed filk fiber as an immobilization support of enzyme

In this study, we attempted to evaluate a novel use of sericin-fixed silk fiber (SFx) as an immobilization support of enzyme. Sericin was fixed on the silk fiber using glutaraldehyde as a fixation reagent. After 6 hours of fixation, the degree of fixation increases linearly with linear decrease of the amount of bound α-chymotrypsin (CT). This suggests that the increase of the degree of fixation is due to the further crosslinking of free aldehyde groups on the surface of sericin-fixed silk fiber (SFx). Even though perfect fixation was not achieved, sericin did not dissolve seriously and could be removed by further washing. The specific activity did not differ significantly after 6 hours of fixation. The activity of immobilized CT on SFx decreased to its half after 6 hours of incubation at 50°C. However, it retained 78% of initial activity even after 1 hour of treatment with 100% ethanol. As a result, the SFx could be used as an immobilization support of enzyme in non-aqueous media at ambient temperature.     

缓释氮肥配施脲酶抑制剂对棉花光合特征的影响

本研究旨在分析缓释肥料（简称“缓释肥”）配施脲酶抑制剂对棉花产量和光合特性的影响。共设不施肥、常规施肥、施缓释肥、缓释肥配施脲酶抑制剂和不同量缓释肥配比搭配脲酶抑制剂5个田间试验处理。研究结果：缓释肥配施脲酶抑制剂处理较常规施肥处理,土壤碱解氮含量增加35.2%,有机质含量增加26.1%;棉花叶片叶绿素荧光参数中,SPAD、反应中心性能指数、最大光化学量子产量、激发能电子转化效率分别增加23.5%、66.3%、14.5%、14.5%,红边归一化植被指数增加13.5%;棉花叶片光合指标中,胞间CO₂浓度、净光合速率、气孔导度、蒸腾速率分别增加30.1%、36.6%、66.9%、27.0%;花铃期,棉花株高、根长、叶面积和单株结铃数显著增加;氮农学利用效率增加96.4%,籽棉产量增加21.5%,肥料偏生产力增加163.5%。上述结果初步表明,缓释肥配施脲酶抑制剂处理能提高棉花的叶绿素功能水平和光合作用,优化棉花的生长指标,有效增加棉花产量。     

Synthesis and flame-retardancy of UV-curable methacryloyloxy ethyl phosphates

Tris[2-methacryloyloxy ethyl] phosphate (TMEP), bis(2-methacryloyloxy) ethyl phosphate (DMEP), and 2-(methacryloyloxy ethyl) phosphate (MMEP) were synthesized from phosphorous oxychloride and 2-hydroxyethyl methacrylate, which can be used as flame retardant monomers for UV-curable coating systems. The characterization of the synthesized monomers was carried out by ¹H-NMR, FT-IR, thermo-gravimetric analysis, and the limited oxygen index (LOI) test. The thermal behavior of the cured films depended on phosphorous content and the methacrylate groups in the monomer. The UVcured films from TMEP, DMEP, and MMEP monomers showed LOIS of 28.5, 30.3, and 35.1 respectively. Also, LOI up to 25.4 was obtained for the UV-coated cotton fabrics, which presumably occur through a condensed phase mechanism as verified in the increased residue number. The higher performance of UV-coated cotton fabrics compared to PET was attributed to the facile dehydration and crosslinking of the cellulosic materials.     

Melt blowing of ionic liquid-based cellulose solutions

The melt-blowing technique is usually used for thermoplastic resins, not for non-thermoplastic materials. In this study, nonwoven fabric was successfully obtained by a cellulose solution through melt-blowing technique. The solution was prepared by a twin-screw extruder after mixing cellulose pulp with 1-Allyl-3-methylimidazolium Chloride ([AMIM]Cl). Nonwoven fabric exhibited typical characteristics of those from melt-blown thermoplastic resins. Some aspects of meltblowing process are discussed, such as cellulose concentration, temperature of extrusion die and hot air pressure. In experimental range, to obtain nonwoven web, cellulose concentration was below 15 wt%. Temperature of extrusion die and hot air pressure had great influence on the fabric. With the increasing of temperature of extrusion die and hot air pressure, the fiber changed thin and the fiber web became better, while the fiber diameter became thicker after increasing the cellulose concentration. Elevating the temperature of extrusion die, the degree of polymerization decreased, and the quality of the fiber webs declined.     

Evaluation of thermomechanical pretreatment for enzymatic hydrolysis of pure microcrystalline cellulose and cellulose from Brewers’ spent grain

Microcrystalline cellulose (Avicel PH102) and Brewers’ spent grain (BSG) were subjected to Détente Instantanée Contrôlée (DIC) thermomechanical pre-treatment before exposure to cellulases (Celluclast 1.5 L). In a first part, we showed that the addition of β-glucosidase (Novozym-188) increased the hydrolysis yield of Avicel. A maximal theoretical yield (100%), was obtained for 5 and 10 g/L of Avicel using a mixture of Celluclast 1.5 L/Novozym-188. After DIC pre-treatments, the initial rate and final yield of hydrolysis decreased in comparison with those from untreated microcrystalline cellulose. This phenomenon may be due to the modification of the crystallinity of pure cellulose and the formation of inhibitors during the pre-treatment. In a second part, BSG was thermomechanically pre-treated and hydrolyzed. The results showed that the hydrolysis yield of BSG treated at pressure levels between 2 and 7 bar during 15 min was strongly improved compared to hydrolysis yield of untreated BSG. The optimized hydrolysis process, under intensive DIC conditions, achieved a glucose yield corresponding to 100% of the theoretical cellulose value. The morphology of BSG samples was studied with Scanning Electronic Microscopy (SEM) and highlighted that the structure of pre-treated BSG showed an important disruption compared to the rigid structure of untreated BSG.     

Properties of flame-retardant cellulose fibers with ionic liquid

Flame-retardant cellulose fibers were prepared by dissolving cellulose in tetrabutylammonium acetate and dimethyl sulfoxide, and blending with amino silicone oil (ASO). The ASO was used as a novel fabric softener and flame retardant for cellulose fibers. Fourier-transform infrared spectroscopy showed that blending with ASO did not adversely affect the cellulose fibers. The flame retardancy of the cellulose fibers blended with ASO was determined based on the limiting oxygen index (LOI). Cellulose fibers blended with 8 wt% (add-on) ASO gave the best flame retardancy, with an LOI of 28, which was higher than that of the virgin fibers. The thermal properties of the flame-retardant cellulose fibers were investigated using differential scanning calorimetry and thermogravimetric analysis. The results showed that ASO prevented degradation of the cellulose fibers, hindered the formation of volatile species, and favored char formation. The mechanical properties of the flame-retardant cellulose fibers were better than those of virgin cellulose fibers.     

Syntheses of flame-retardant cellulose esters and their fibers

3-(Hydroxyphenylphosphinyl)-propanoic acid (3-HPP) esters of cellulose (HPP-Cellulose) were synthesized homogeneously in ionic liquid 1-butyl-3-methylimidazoliumchloride by in situ activation. The chemical structure of the cellulose esters is characterized by FTIR and NMR. The degree of substitution was easily controlled within 0.38-1.51 by varying the molar ratio of 3-HPP/anhydroglucose unit, reaction time, and temperature. All the products showed excellent solubility in common organic solvents. The results of TGA, DTG, LOI, and cone calorimeter test show that 3-HPP has a positive influence on the thermal properties and flame retardance of cellulose. Based on the volatilized products analysis by TGA-IR, the presence of 3-HPP reduces the intensity of volatilized product and accelerates the dehydration action. Moreover, the addition of cellulose (3 wt%) is beneficial to prepare HPP-Cellulose fibers using a dry-wet spinning technique, and the blended fibers possess good mechanical properties as well as flame resistance.     

Preparation of carboxymethyl cellulose superabsorbents from waste textiles

Production of superabsorbent polymers from cotton and viscose waste textiles was investigated. The cellulose wastes were carboxymethylated, crosslinked by divinylsulfone, and then converted to superabsorbent material using air-drying, freeze-drying, or air-drying after phase inversion. The separation of cellulose from synthetic polymers in the textile (polyester) was carried out by direct dissolution of cellulose in N-methylmorpholine-N-oxide (NMMO), or separation by dissolution in water after carboxymethylation of the textiles. The progress of the carboxymethylation reaction was evaluated by measurement of the degree of substitution (DS) of carboxymethyl cellulose (CMC). The DS values of 0.50–0.86 confirmed the prosperous substitution of hydrophilic carboxymethyl groups into the cellulosic chains. The water binding capacity and the swelling rate of the superabsorbents prepared under different conditions were measured. Under the best condition the superabsorbent obtained from waste textiles showed an ultimate water binding capacity of 541 g/g which was notably higher than that of the reference superabsorbent derived from cotton linter (470 g/g). The amount of absorbed water by this product exceeded that of the reference sample after 60 min immersion.     

Optimization of acid cellulose enzyme concentration to reduce pilling of bamboo fabric: An objective assessment approach

Enzymes are being extensively used in industry as they are environmentally friendly. They show a variety of advantages over chemicals, like their specificity, high efficiency and eco-friendliness. Nowadays different kinds of cellulase enzyme mixtures are commercially formulated for the finishing of cellulosic fabrics. This study investigated the effect of acid cellulase treatment on bamboo knitted-fabric to reduce pill. It has been observed that specific range of concentration only can effectively reduce pills with substantial weight loss. The common process and method followed by a textile chemist to optimize or standardize the concentration of enzyme treatment to reduce pill is still cumbersome and doubtful. A quicker and objective method is proposed to optimize the concentration of enzyme. The effectiveness is evaluated using standard Martindale tester and the weight loss of the fabric.     

Application of electrospun silk fibroin nanofibers as an immobilization support of enzyme

Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to 5.6 wt%. The activity of immobilizedα-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at 25°C by retaining more than 90 % of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than 45% of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.