Preparation and characterization of novel forward osmosis membrane incorporated with sulfonated carbon nanotubes

In this study, carbon nanotubes (CNTs) were modified with sulfonated groups and incorporated into the active layer of a forward osmosis (FO) membrane to achieve a desirable thin-film nanocomposite (TFN) FO membrane. Different concentrations of sulfonated carbon nanotubes (SCNTs) were added, and their impact on the FO membrane was also investigated, including the hydrophilicity, roughness, membrane morphology and FO performance. With the addition of SCNTs, the membrane surface got smoother and denser, and the hydrophilicity also improved significantly. Regarding FO performance, SCNTs-functionalized FO membranes exhibited higher water flux (J_w) and lower reverse salt flux (J_s). The optimal J_w of 29.9 ± 1.6 LMH was achieved by using 1 M NaCl solution as the draw solution (DS) and deionized (DI) water as the feed solution (FS), almost 140% higher than the control (21.3 ± 2.1 LMH) and J_s decreased to about 12%.

In this study, carbon nanotubes (CNTs) were modified with sulfonated groups and incorporated into the active layer of a forward osmosis (FO) membrane to achieve a desirable thin-film nanocomposite (TFN) FO membrane.     

Preparation and characterization of chitosan membranes

The present study investigates a new solvent system for the dissolution of chitosan and a new method for preparing chitosan membranes. First, aqueous tartaric acid was used to pretreat chitosan. Then, the chitosan was precipitated with ethanol or other regenerating agents, and 1.5 mL of 1-ethyl-3-methylimidazolium acetate ([EMIM]AC) was added to obtain translucent suspensions. The chitosan membranes were prepared by casting the suspensions on glass plates and allowing solvent evaporation. The structure and properties of the films were investigated by SEM, FT-IR, XRD and TGA. Also, the mechanical properties, as well as physical and chemical characteristics, of the chitosan films were evaluated. The results indicated that the optimum dissolution time was 10 min and the most suitable drying temperature was 60 °C. The thus-prepared film was moderately thick (about 0.02 mm) and had a smooth surface, without curling. The chitosan film prepared by ethanol regeneration had a tensile strength of up to 24 MPa, a minimum swelling degree of 78%, and a water vapor transmission rate of 270 g m⁻² d⁻¹ without the addition of plasticizer.

The present study investigates a new method for preparing chitosan membranes. The thus-prepared film was moderately thick and had a smooth surface, without curling.     

One-pot synthesis of cup-like ZSM-5 zeolite and its excellent oxidative desulfurization performance

A one-step method to synthesize small size cup-like hollow ZSM-5 single crystals is reported in this paper. Characterization methods show that the product has a typical ZSM-5 structure and most crystals are uniform, mono dispersed crystal shells with distinct hollow structure. The average size of a single crystal is about 350 nm. Every cup-like hollow ZSM-5 crystal can act as a microreactor in the reaction, and the ZSM-5 based catalyst POM-MOF-ZSM-5 (polyoxometalates (POM), metal–organic frameworks (MOF)) shows excellent oxidative desulfurization performance of DBT (dibenzothiophene).

One-pot synthesis of small size cup-like hollow ZSM-5 single crystals and their oxidative desulfurization performance.     

Preparation and characterization of a novel positively charged composite hollow fiber nanofiltration membrane based on chitosan lactate

A positively charged composite hollow fiber nanofiltration (NF) membrane was prepared via interfacial polymerization (IP) between chitosan lactate (CL) and trimesoyl chloride (TMC) on a polyether sulfone (PES) hollow fiber ultrafiltration (UF) membrane. The chemical structure and the morphologies of the resultant NF membranes were characterized with attenuated total reflectance-infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). The rejection of NF membrane for different inorganic salt aqueous solutions followed the order: MgCl₂ > ZnCl₂ > MgSO₄ > NaCl > Na₂SO₄. It suggested that this novel kind of composite hollow fiber NF membrane is positively charged. The molecular weight cut-off (MWCO) was obtained through the rejection of polyethylene glycol (PEG) solutions with different molecular weights (M_w). The effect of monomer concentrations, the interfacial polymerization time, and the curing temperature, were investigated, respectively. The rejection and the permeate flux of the resultant composite hollow fiber CL membrane fabricated under the optimal conditions towards a MgCl₂ solution of 1000 ppm were 95.1% and 10.3 L m⁻² h⁻¹, respectively, at 0.4 MPa and 25 °C. Moreover, the effects of operation conditions on the rejection performance of the composite hollow fiber NF membrane were investigated. It suggested that this novel kind of hollow fiber composite nanofiltration membrane based on CL have excellent stability in rejection performances to salt solutions.

A positively charged composite hollow fiber nanofiltration (NF) membrane was prepared via interfacial polymerization by using chitosan lactate and trimesoyl chloride (TMC).     

壳聚糖纳米粒制备及表征与其抗肿瘤的生物学效应

目的:近期研究发现,壳聚糖纳米化后,不仅可改善其溶解性,还可提高其生物学功能。拟建立壳聚糖纳米粒的制备方法,并对壳聚糖纳米粒的表征及抗肿瘤生物学效应进行初步研究。方法:实验于2006-08/2007-05在浙江省医学科学院生物工程所完成。①建立壳聚糖纳米粒的制备方法:将壳聚糖粉末溶于乙酸溶液,用NaOH调节其pH为5,采用三聚磷酸钠为凝聚剂,进行离子交联来制备壳聚糖纳米颗粒。通过离心和冷冻干燥得到壳聚糖纳米粒粉末。②纳米粒的表征:经超声得到壳聚糖的悬浊液,用透射电镜来观察纳米颗粒的外观形态;用动态光散射仪来测定纳米颗粒的粒径大小与分布。③采用MTT法对壳聚糖纳米粒体外抗肿瘤生物学效应进行了初步研究。结果:①透射电镜下观测到了稳定、均一的颗粒;激光粒度分析仪测量发现纳米粒粒径大小在300nm左右,粒径分布较窄。②500mg/L的壳聚糖纳米粒对Hela细胞的抑制率为27%;对SMMC-7721细胞的抑制率为23%;对BGC-823细胞的抑制率为29%;对MCF-7细胞的抑制率最高,达55%。结论:建立的壳聚糖纳米粒的制备方法可靠,并证明其体外具有较好的抗肿瘤作用。     

丝素蛋白/壳聚糖三维多孔支架的构建及结构表征

背景：丝素蛋白和壳聚糖均无毒性且具有良好的生物相容性,但是单一成分作为生物支架时都不能满足支架材料的需求。目的：制备各种不同组分的丝素蛋白及壳聚糖复合支架材料,观察其微观结构及相关性能,筛选出适合成骨细胞生长的理想支架材料。方法：通过CaCl2：C2H5OH：H2O=1：2：8（摩尔比）溶解体系溶解、过滤、浓缩提纯,制备出2%的丝素蛋白溶液,壳聚糖溶解于乙酸溶液配制成的3%壳聚糖溶液,将两者以不同的比例相混合,经数次冷冻干燥后,得到成品支架材料。采用电镜观察形貌,计算孔隙率并对支架的结构进行红外、X射线衍射、电子能谱分析观察。结果与结论：将壳聚糖和丝素蛋白共混后,互为改性,制备出了结构较稳定的支架材料。其中40%丝素蛋白-60%壳聚糖组具有适合成骨细胞生长的较佳孔径,可作为细胞支架的首选配比。     

聚乳酸/壳聚糖纤维复合支架的制备与性能

背景:聚乳酸/壳聚糖纤维复合支架材料既可提高支架的力学性能,又可中和聚乳酸的酸性降解产物,提高生物相容性,从而满足组织工程支架的要求.目的:制备用于组织工程的聚乳酸/壳聚糖纤维复合支架.方法:采用热致相分离法制备了聚乳酸/壳聚糖纤维复合支架.测定了复合支架的微观形貌、孔隙率、压缩模量、降解特性、蛋白质吸附特性.结果与结论:复合支架具有纳米微米共存的亚微观结构.在聚乳酸纳米纤维网络中引入壳聚糖纤维,有效地增强了复合支架的压缩模量和蛋白质吸附能力,复合支架压缩模量为纯聚乳酸纳米支架的3.75倍,蛋白质吸附能力比纯聚乳酸纳米支架提高了112%.体外降解实验表明复合支架降解液的pH值随时间的下降明显变缓.提示,在聚乳酸纳米纤维网络中引入壳聚糖纤维,可有效增强支架的压缩模量,提高蛋白质吸附能力,并可有效减缓聚乳酸降解过程中pH值的下降,克服酸性产物引发的无痛性炎症问题.     

一种壳聚糖神经组织工程支架的制备及表征

目的:用自行研制的模具制备一种具有轴向排列多通道壳聚糖神经修复导管.方法:实验于2004-05/09在清华大学生物系生物材料与组织工程实验室完成.首先制备多孔或致密的壳聚糖空管,管内径为2～5 mm,壁厚0.2～1.0 mm.将一组不锈钢针平行贯穿于壳聚糖空管,用钢针固定片固定不锈钢针,然后在此壳聚糖空管中注入壳聚糖溶液,最后用冷冻干燥法成型.然后,对所得到的支架进行理化性能表征,评价多通道壳聚糖导管的溶胀性、体外降解情况,并用瑞氏染色与扫描电镜用来观察N2a细胞(Neuroblastoma cells, mouse)在导管内生长情况.结果:①在0.1 mol/L磷酸盐缓冲液中溶胀后,多通道壳聚糖导管的内径无显著性变化(P > 0.01),管壁厚度增大明显(P < 0.01).②导管在溶菌酶溶液中降解8周后,形态结构无明显变化,而且保持了足够的机械强度和韧性.③瑞氏染色显示N2a细胞核染成深蓝色,铺展在通道表面及成团分布在导管内基质之中.扫描电镜观察可清晰地显示出细胞的形态及在导管中的分布情况.结论:实验制备的多通道壳聚糖导管具有合适的溶胀性、机械强度以及神经细胞亲和性,有潜在的研究与应用价值.     

Preparation and characterization of liposomes with incorporated Neisseria gonorrhoeae protein ib and amphiphilic adjuvants

Liposomes were prepared according to a three-step procedure. Octylglucoside, lipid and optionally protein (outer membrane protein IB from N. gonorrhoeae), lipid A or dimethyldioctadecylammonium bromide (DDA) containing mixed micelle dispersions were diluted, then dialysed and finally filtrated. The liposome preparations were characterized for their particle size (both freshly prepared and after storage) and the contents of the different constituents. Data on the orientation of protein IB in the bilayer were collected. Stable, well-defined liposomes could be obtained with egg phosphatidylcholine/cholesterol bilayers containing optionally DDA or lipid A with or without protein IB. For dipalmitoylphosphatidylcholine/cholesterol combinations a charge-inducing agent (DDA or dipalmitoylphosphatidylglycerol [DPPG]) was required to stabilise the liposomes which further contained (optionally) lipid A (only with dipalmitoylphosphatidylcholine/cholesterol/ DPPG) with or without protein IB. In general, the uptake of all constituents into the bilayer was almost quantitative. Enzymatic degradation experiments showed that protein IB had the same orientation and surface exposure as in the bacterial outer membrane.     

Synthesis,characterization, and catalytic application of hierarchical nano-ZSM-5 zeolite

Hierarchical nano-ZSM-5 zeolites (Z5-X) with different grain sizes were synthesized by varying amounts of 3-glycidoxypropyltrimethoxysilane (KH-560) in the hydrothermal synthesis strategy. Moreover, the conventional ZSM-5zeolite(Z5), which was prepared without KH-560, was used as the reference sample. The crystalline phases, morphologies, porous characteristics, Si/Al molar ratios and acidic properties of all fresh catalysts were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), N₂ adsorption–desorption, inductively coupled plasma atomic emission spectroscopy (ICP) and temperature programmed desorption of ammonia (NH₃-TPD) techniques. Results show that the grain size and strong acid amount of zeolite decreased with the increasing amount of KH-560. The micropore surface areas and the corresponding volume of Z5-X changed less compared with Z5. Consequently, the high shape-selectivity of zeolite was preserved well under the addition of KH-560. However, the mesopore surface areas and the corresponding volume increased significantly with the increasing amount of KH-560. Benefiting from the abundant hierarchical structure, the Z5-X catalysts exhibited a larger coke capacity than the Z5 catalyst. The coke depositions of all the deactivated catalysts were characterized by the thermogravimetric technique (TG), and the results are indicative of the decreased average rate of coke deposition with an increasing amount of KH-560, which could result from the gradually reduced strong acid amount and the nano-sized crystallites. The catalytic performance of methanol-to-aromatics (MTA) indicates that the Z5-0.12 catalyst exhibited higher catalytic activity and selectivity of BTX as the reaction was prolonged, which could result from the synergistic effect among the proper strong acid amount, the smaller zeolite grain size, and the abundant hierarchical structure.

The crystal size and strong acid amounts of ZSM-5 decrease and the mesopores increase with increasing of KH-560. High MTA catalytic performance could be obtained under synergistic effect of proper strong acid amount, smaller crystal size and abundant hierarchical structure.