Ti-O薄膜表面明胶接枝改性及其细胞相容性

进行 3-氨丙基膦酸(APP)在Ti-O薄膜表面的自组装并在其表面接枝明胶分子,研究了细胞相容性.结果表明,APP自组装的最佳温度为80℃,时间为4 h,自组装后水接触角降低,表面C、N元素含量提高;表面明胶在模拟体液中前4d有少量释放,之后体系稳定,稳定后表面明胶的有效密度为2.3μg/cm2.接枝改性后的Ti-O薄膜表面促进了内皮细胞的生长和增殖,提高了表面的细胞相容性.     

Covalent grafting of carbon nanotubes to PLA in order to improve compatibility

An excellent methodology for the synthesis of nanocomposite materials using a biodegradable polymer as matrix (polylactic acid, PLA) and functionalized by Fenton reaction carbon nanotubes (fMWCNTs) as reinforcement was developed. PLA was modified with benzoyl chloride and both modified materials were bounded covalently by esterification reaction. Infrared spectroscopy (FTIR) and thermogravimetry (TGA) studies were performed to verify the synthesis of the composites obtained. Films based on modified PLA reinforced with fMWCNTs (PLAmfMWCNTs) were conformed observing excellent dispersion of the filler in the PLA matrix. Finally it was shown that the addition of fMWCNTs improves Young’s modulus and strength without losing deformation. Also it was observed that the good stability of the film let us to process it until 300 °C. Taking into account all these results, the new biodegradable nanocomposite material developed could be very promising to be used in packaging and biomedical industries as a replacement of the synthetic materials.     

交联黄原酸化壳聚糖树脂对水溶液中棒曲霉素的吸附

以壳聚糖为吸附剂,戊二醛作为交联剂,采用反相悬浮交联法制备球状壳聚糖树脂,利用二硫化碳作为改性剂,在碱性条件下对壳聚糖树脂进行黄原酸化改性,制备成交联黄原酸化壳聚糖树脂(crosslinked xanthated chitosan resin,CXCR)。对CXCR进行红外表征,并研究了其对水溶液中棒曲霉素的吸附性能。结果表明,CXCR在棒曲霉素初始浓度为8 mg/L,CXCR用量为1 g/L,溶液p H值=4,25℃下吸附16 h,吸附量可达6.53 mg/g,可有效地吸附水溶液中的棒曲霉素。CXCR对棒曲霉素的吸附符合拟二级动力学模型;吸附热力学符合Freundlich吸附等温线模型。CXCR有望作为一种新型的材料用于棒曲霉素的吸附,具有广阔的应用前景。     

一种水溶性壳聚糖的制备及用于微囊化细胞培养的研究

为了提高壳聚糖的水溶性,通过一种简单的均相介质中N-乙酰化方法制备了水溶性壳聚糖。利用傅里叶红外光谱仪、核磁共振仪和X射线衍射仪表征了水溶性壳聚糖的脱乙酰度(DD)、官能团结构和结晶状态,进一步分析了其水溶机理。初步验证了水溶性壳聚糖用于微囊化细胞培养的可行性,结果表明,水溶性壳聚糖脱乙酰度为56%,在乙酰化过程中,晶体的结晶度降低而形成无定形结构是其水溶的主要原因;细胞在水溶性壳聚糖制备的微胶囊中保持良好的活性,在培养过程中逐渐聚集成团生长。     

Antimicrobial activity of chitosan attached to ethylene copolymer films

Ethylene copolymer film was coated with chitosan by attachment of the polymer to the corona‐treated surface of the film, and the composite film was analysed for antimicrobial activity. The film was active against bacteria in 0.625 mM phosphate buffer; it reduced colony counts of Escherichia coli 25922 and of Listeria monocytogenes Scott A by 5 and 2–3 log₁₀, respectively after 24 h exposure. The activity of the chitosan‐coated film against bacteria in buffer was increased when silver ions were incorporated into the films as demonstrated by complete killing of Escherichia coli O157:H7 DD3795 and the chicken exudate isolate Stenotrophomonas maltophilia within 2 h in buffer. The film was active against L. monocytogenes Scott A in 0.5% buffered peptone water up to a pH of about 7.0. Tests on beef and chicken meat exudates revealed antimicrobial activity of the film against Escherichia coli O157:H7 and L. monocytogenes Scott A of about 2 and 1–2 log₁₀ reductions in colony‐forming units, respectively. The antimicrobial activity of the film against L. monocytogenes Scott A was also tested on turkey breast, and a log₁₀ reduction of about 1.7 log₁₀ units after 10 days and 1.2 log₁₀ after 15 days at 4°C was achieved. Exposure to chitosan‐coated film and 350 MPa of pressure, 55°C or 1% sodium diacetate resulted in a synergistic effect. Copyright © 2008 John Wiley & Sons, Ltd     

核孔膜乳化法制备单分散壳聚糖微球

选择壳聚糖溶液为分散相,液体石蜡为连续相,首次采用核孔膜乳化方法制备壳聚糖微球.乳滴经戊二醛交联固化后所得微球球形度和单分散性良好(分散系数＜20%).主要研究了核孔膜孔径大小、油水相体积比、表面活性剂种类及用量、温度和固化时间对微球制备的影响.结果表明,膜乳化法是制备单分散微球的良好方法.     

Characterization of chitosan films and effects on fibroblast cell attachment and proliferation

Chitosan has been researched for implant and wound healing applications. However, there are inconsistencies in reports on the tissue and fibroblast responses to chitosan materials. These inconsistencies may be due to variations in chitosan material characteristics. The aim of this study was to correlate fibroblast responses with known chitosan material characteristics. To achieve this aim, chitosan was characterized for degree of deacetylation (DDA), molecular weight (MW), residual protein and ash contents, and then solution cast into films and characterized for hydrophilicity by water contact angle. The films were seeded with normal human dermal fibroblasts and the number of attached cells was evaluated for after 30 min. Cell proliferation was evaluated over 5 days. This study found no relationship between DDA, contact angle, cell attachment, and or proliferation. General trends were observed for increasing proliferation with increasing residual ash content and decreasing residual protein. These data indicate that chitosan characteristics other than DDA may be important to their biological performance.     

Approaches to improve compatibility of starch filled polymer system: A review

When hydrophilic starch is incorporated into synthetic polymers, the resulting products are weakened, especially blending with hydrophobic polymers. Many researchers have been undertaking various approaches to improve compatibility of starch and synthetic polymers. However, no ultimate and comprehensive approach can be determined. This paper aims to investigate and discuss the improvement approaches which have been recently developed by researchers. Also, the extents of improvement are summarized as well. In order to simplify this review, synthetic polymers are categorized into polar and non-polar types. Low density polyethylene was studied as non-polar type polymer, while polyvinyl alcohol was studied to represent as polar type polymer. Both types of synthetic polymers were blended with starches and their results were reported well by researchers. All findings are very informative and further encourage research for other starch filled polymer systems as well. In short, appropriate modifications to starch filled polymer system would induce polarity of the materials and subsequently create harmonious intermolecular interactions among blending components for better product properties.     

ZnO nanoparticles induced effects on nanomechanical behavior and cell viability of chitosan films

The aim of this paper is to develop novel chitosan–zinc oxide nanocomposite films for biomedical applications. The films were fabricated with 1, 5, 10 and 15% w/w of zinc oxide (ZnO) nanoparticles (NPs) incorporated with chitosan (CS) using a simple method. The prepared nanocomposite films were characterized using atomic force microscopy, Raman and X-ray diffraction studies. In addition, nano and micro mechanical properties were measured. It was found that the microhardness, nanohardness and its corresponding elastic modulus increased with the increase of ZnO NP percentage in the CS films. However, the ductility of films decreased as the percentage of ZnO NPs increased. Cell attachment and cytotoxicity of the prepared films at days two and five were evaluated in vitro using osteoblasts (OBs). It was observed that OB viability decreased in films with higher than 5% ZnO NPs. This result suggests that although ZnO NPs can improve the mechanical properties of pure CS films, only a low percentage of ZnO NPs can be applied for biomedical and bioengineering applications because of the cytotoxicity effects of these particles.     

Mechanical properties of multilayered films using different nanoindenters

The effects of interface, contact hardness, deformation, and adhesion of Al/Ni multilayered films under nanoindentation were investigated using molecular dynamics (MD) simulations. The results show that the indentation force of the sphere indenter is the largest among nanoindentations using sphere, cone, Vickers, or Berkovich type indenters at the same penetration depth. Force increasing, relaxation and adhesion took place during loading, holding depth and unloading, respectively. The interface occurred along the {111} (110) slip systems and the maximum width of the glide bands was about 1 nm. The reaction force and plastic energy of the indented films are also discussed.     

Preparation of diamond-like carbon films by cathodic micro-arc discharge in aqueous solutions

Diamond-like carbon films (DLC) and silicon doped diamond-like carbon films were deposited on Ni substrate by cathodic micro-arc discharge at room temperature in aqueous solutions. The deposit potential was 130 V. The structure of the films was characterized by a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectra and XPS analysis demonstrated that the films were diamond-like carbon clearly. SEM observation showed that the DLC films were uniform and the thickness was about 200 nm. Potentiodynamic polarization curve indicated the corrosion resistance of the Ni substrate was markedly improved by DLC films.     

医用不锈钢的细胞膜仿生表面修饰

利用2-（甲基丙烯酰氧基）乙基-2-（三甲基氨基）乙基磷酸酯（MPC）与316L不锈钢表面上γ-氨基丙基三乙氧基硅烷（KH550）的Michael加成反应,将MPC化学接枝到不锈钢的表面．修饰表面的XPS结果证实了MPC的成功接枝,表明在不锈钢表面构建了仿细胞膜表面．体外血小板粘附实验显示,修饰表面具有明显阻抗血小板的粘附、聚集和激活性能,并具有良好的血液相容性．     

Preparation and HL-7702 cell functionality of titania/chitosan composite scaffolds

Titania/chitosan composite scaffolds were prepared through a freeze-drying technique. The composite scaffolds were highly porous with the average pore size of 120–300 μm, and the titania (TiO₂) powders were uniformly dispersed on the surface of the pore walls. The compressive strength of the composite scaffolds was significantly improved compared to that of pure chitosan scaffolds. Composite scaffold with 0.3 of TiO₂/chitosan weight ratio showed the maximum compressive strength of 159.7 ± 21 kPa. Hepatic immortal cell line HL-7702 was used as seeding cells on the scaffolds, and after different culture periods, cell attachment and function was analyzed. HL-7702 cells attached on the pore walls of the scaffolds with the spheroid shape after 1 day of culture, but more cell aggregations formed within the TiO₂/chitosan composite scaffolds as compared to pure chitosan scaffolds. Liver-specific functions, albumin secretion and urea synthesis were detected using a spectrometric method. The results showed that albumin secretion and urea synthesis rate of HL-7702 cells slightly decreased with the culture time, and there was no significant difference between composite scaffolds and pure chitosan scaffolds. In conclusion, the TiO₂/chitosan composite scaffolds possessed an improved mechanical strength compared to pure chitosan scaffolds and supported the attachment and functional expression of hepatocyte, implying their potential application in liver tissue engineering.     

Preparation of silicon carbide foams using polymeric precursor solutions

A simple method was developed to produce silicon carbide foams using polysilane polymeric precursors. Polyurethane foams were immersed in polysilane precursor solutions to prepare pre-foams. Subsequently, these were heated in nitrogen at different temperatures in the range of 900°C to 1300°C. The silicon carbide foams produced in this manner showed well-defined open-cell structures and the struts in the foams were free of voids. The shrinkage which accompanies pyrolysis of the pre-foams was reduced with increasing the concentration of the polymeric precursor solutions.     

肝素和聚氨酯同溶液体系混合接枝及其抗凝血性

利用全新的四氢呋喃和水的溶液体系将肝素与不溶于水的聚氨酯同溶液混合,制备出含有肝素的聚氨酯薄膜利用碳二亚胺缩合反应将肝素接枝在聚氨酯分子上以改善材料的长效抗凝血性.在肝素过量的情况下,制备出同时含有游离和接枝肝素的聚氨酯薄膜,并初步评价了薄膜中肝素的扩散速率以及体外抗凝血性.结果表明,肝素均匀分布在薄膜中,肝素活性保持良好,扩散缓慢,具有相对长效的抗凝血活性.接枝后的肝素仍具有良好的生物活性,同时含有接枝和游离肝素薄膜的抗凝血性优异.     

Processing of polyethylene terephthalate fiber reinforcement to improve compatibility with constituents of GFRP nanocomposites

The aim of the present research was to improve the impact strength of epoxy-based glass fiber-reinforced nanocomposites by the addition of polyethylene terephthalate (PET) fibers as reinforcement along with nanoclay. Hybrid nanocomposites containing clay as nano-filler and PET fibers as micro-reinforcement were fabricated. Nanocomposites with 1?phr clay and varying concentrations of PET fibers (1–3?phr) were processed using a vacuum-assisted hand layup. Addition of untreated PET fibers did not improve the impact strength of nanocomposites due to the lack of interaction between the inert PET fibers and other constituents. To improve the interfacial interaction, two different compatibilization procedures for the surface modification of PET fibers were used. In the first procedure, silane treatment of fibers was performed using two separate silane agents. In the second method, maleic anhydride (MAH) grafting was performed in the presence of ultraviolet radiations. Compatibilization of fibers was confirmed with scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR). The results of impact and tensile testing showed an improvement of 19% in the impact strength of nanocomposites at 2?phr silane-treated PET fiber loading without significant loss in tensile strength. Finally, scanning electron micrographs of various nanocomposites were analyzed to correlate with the improved impact strength.     

Hydroxyapatite-based ceramic materials prepared using solutions of different concentrations

Hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂, powders with enhanced sinterability have been synthesized through precipitation from calcium nitrate and ammonium hydrogen phosphate solutions at pH 9, t= 60°C, and a Ca/P atomic ratio of 1.67, and their properties have been studied: phase composition, particle size distribution, loose density, and green density. The initial solution concentration is shown to influence the properties of the powders and the ceramics fabricated from them. Comparison of the particle size distributions in disaggregated powders and the grain size distributions in the ceramics indicates that the ceramics inherit the structure of the corresponding powders. Optimizing the synthesis conditions in order to enhance the sinterability of the powders, we obtained green compacts with the highest shrinkage rate in the range 850–950°C and shrinkage onset at 600°C, which is 100–150°C lower in comparison with powders synthesized in earlier studies from calcium nitrate and ammonium hydrogen phosphate.