利用胶原-肝素自组装多层膜改善纯钛表面血液相容性的研究

为了改善钛表面的血液相容?用层层自组装技术将抗凝药物肝素和细胞外基质成分之一的胶原层层交替吸附到钛表面,形成多层薄膜,使具有良好的抗凝血功能.钛通过氢氧化钠处理表面带负电,在聚赖氨酸溶液中会吸附一层带正电的聚赖氨酸,然后将其交替浸泡于带负电的肝素和带正电的胶原中形成自组装薄膜.通过傅立叶红外漫反射(FTIR)检测材料表面基团的变化,通过测水接触角的方法跟踪组装过程,通过扫描电子显微镜(SEM)观察材料表面形貌的变化.血小板黏附实验显示钛改性后表面血小板黏附量明显减少,且反映血小板激活程度的P-selectin的表达量结果也显示,钛改性后表面血小板激活程度显著降低,活化部分凝血活酶时间(APTT)和外源性凝血系统的凝血酶原时间(PT)的实验显示钛改性后表面凝血时间延长,血液相容性得到改善.研究说明这种方法对于心血管材料钛的改性有重要价值.     

肝素和Ⅳ胶原在Ti表面组装及不同组装层数对内皮祖细胞的影响

利用层层自组装技术将带有相反电荷的肝素和Ⅳ型胶原交替组装到材料表面,研究了组装前后及不同组装层数对内皮祖细胞的影响。Ti通过碱活化处理后,表面带上羟基,与多聚赖氨酸中的羧基结合,使材料形成带正电荷的氨基表面,接着将带有异种电荷的肝素和Ⅳ型胶原交替滴加到材料表面形成多层自组装层。通过傅立叶红外掠射检测各步处理后材料表面基团的变化,通过甲苯胺蓝定量表征材料表面肝素组装量,通过原子力显微镜观察组装前后材料表面形貌变化,通过水接触角的测定跟踪组装过程中材料表面亲疏水性能变化。结果显示肝素和Ⅳ型胶原成功地组装到材料表面,修饰后的表面较Ti表面内皮祖细胞的粘附数量多,随着组装层数的增加,细胞在材料表面粘附数量也逐渐增加,且其生长与增殖逐步加快。     

层层自组装法制备肝素微囊及其性能研究

以海藻酸钙微核为模板,采用带正电荷的聚稀丙基铵盐酸盐(PAH)和带负电荷的肝素钠(HEP),通过层层自组装(Layer-by-layer,LbL)技术构建具有多层膜结构和抗凝血活性的药物微囊.采用荧光倒置显微镜、SEM、动态光散射仪、Zeta电位仪和抗凝血仪等进行表征.结果表明,制备的海藻酸钙微核粒径约为1.5μm,尺寸均匀、分散性佳;以ALG为模板制得的LbL微囊具备典型的核壳式结构;Zeta电位检测表明,随包膜层数的增加,微囊的电位呈正负交替的变化趋势;通过体外凝血时间(PT、APtt、TT)检测微囊抗凝血活性,比较了分别以PAH和HEP作为最外层时的生物活性,其中以HEP为最外层的显著增强了材料的抗凝血性能,同时随着组装层数的增加,也提高了微囊的抗凝血性能.     

钛材料表面固定多聚赖氨酸-肝素纳米颗粒以改善血液相容性的研究

通过将多聚赖氨酸(PLL)-肝素纳米颗粒固定在多巴胺涂覆的钛表面,以改善其血液相容性。利用zeta电位仪及甲苯胺蓝法检测纳米颗粒的粒径及成分,通过傅立叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)及水接触角等对颗粒固定前后表面理化性质的变化进行表征。通过体外血小板粘附实验、肝素释放及活化部分凝血活酶时间(APTT)检测对改性样品的血液相容性进行评价。结果表明,PLL-肝素纳米颗粒成功固定在多巴胺沉积的钛表面,纳米颗粒的固定有效降低钛材料表面血小板的粘附行为,大大提高了血液相容性。     

聚氨酯表面层层自组装Ⅰ型胶原和硫酸软骨素

以可降解聚氨酯(PU)为基体,通过丙二胺的胺解作用,在PU材料的表面接上氨基基团,然后利用层层自组装技术在其表面交替地组装上Ⅰ型胶原和硫酸软骨素。经石英微晶天平、罗丹明异硫氰酸酯标记胶原荧光光谱法和X射线光电子能谱分析测试,结果表明Ⅰ型胶原和硫酸软骨素交替地吸附在PU材料表面;原子力显微镜观察结果显示,在PU材料表面组装上Ⅰ型胶原和硫酸软骨素后,材料的表面变得更平整,形成了比较均一的纳米级形貌结构。     

聚氨酯表面层层自组装Ⅰ型胶原和硫酸软骨素EI北大核心CSCD

以可降解聚氨酯(PU)为基体,通过丙二胺的胺解作用,在PU材料的表面接上氨基基团,然后利用层层自组装技术在其表面交替地组装上Ⅰ型胶原和硫酸软骨素。经石英微晶天平、罗丹明异硫氰酸酯标记胶原荧光光谱法和X射线光电子能谱分析测试,结果表明Ⅰ型胶原和硫酸软骨素交替地吸附在PU材料表面;原子力显微镜观察结果显示,在PU材料表面组装上Ⅰ型胶原和硫酸软骨素后,材料的表面变得更平整,形成了比较均一的纳米级形貌结构。     

层层自组装可食用保鲜膜的性能探究

目的对可食用保鲜膜的性能进行拓展。方法采用层层自组装静电沉积法制备可食用水果保鲜膜,并对膜进行表征,探究膜的微观结构、透明度、亲疏水性、自修复性等。结果该可食用膜结构致密,具有较好的透明度,透光率在90%以上;具有较好的疏水性,接触角θ约为102°;能实现形貌和力学性能上的修复,修复前后的膜都能负载200 g的砝码,同时都无法负载300 g的砝码。结论可食用保鲜膜的这些性能提高了该可食用膜的保鲜效果。     

层层自组装技术在智能表面材料中的应用进展

层层自组装作为一种纳米表面图案化技术,具有操作过程简单、实施成本低、结构动态可控、适用材料广泛等特点,其中动态可控表面微结构赋予了材料独特的理化性能,是智能材料领域研究的热点。该技术在生物医药、传感器、信息存储、膜分离等领域具有广阔的应用前景。综述了基于层层自组装技术的智能表面材料及其在不同领域的应用进展,并对其发展前景进行了展望。     

钛表面自组装牛血清白蛋白以控制血小板粘附行为的研究

将牛血清白蛋白通过自组装方法组装到钛表面,以改善其血液相容性.首先,用氢氧化钠活化钛,得到有活性羟基且带负电荷的多孔表面,然后浸入带正电荷的聚赖氨酸溶液,最后浸入带负电荷的牛血清白蛋白溶液.通过扫描电子显微镜(SEM)和原子力显微镜(AFM)观察自组装前后表面形貌变化,通过傅立叶红外漫反射(FTIR)检测各步处理层表面基团变化,通过视频接触角观察各步处理后钛表面接触角变化,通过体外血小板粘附实验评价自组装前后表面血液相容性变化.实验结果表明,牛血清白蛋白组装到钛表面后,血小板的粘附行为得到有效控制,钛表面的血液相容性显著改善.     

共价层层自组装纳滤膜的制备及性能研究

纳滤膜目前多采用界面聚合的方法制备.层层自组装是近年来发展的一种新型制膜方法,但层层自组装所制备的纳滤膜大多需要5个以上双层,制备过程繁琐,同时,以静电力结合的阴阳离子聚电解质在水中存在一定程度的解离和溶胀,结构不稳定.本文提出用静电组装与化学交联相结合的方法制备纳滤膜,增强膜的稳定性.以改性的聚丙烯腈(PAN)为基膜,以聚丙烯酸(PAA)和聚乙烯亚胺(PEI)分别为阴阳离子聚电解质,以戊二醛(GA)为交联剂,制备了共价层层自组装纳滤膜(PEI/PAA/GA)n,研究了双层数、交联剂浓度、交联时间等因素对膜性能的影响.结果表明,当制备两个双层时,(PEI/PAA/GA)_2纳滤膜对2 000 mg/L Na_2SO_4溶液中的Na_2SO_4的截留率就能达到98.1%,水通量为12.6 L/(m~2·h·MPa);对2 000 mg/L NaCl溶液中的NaCl的截留率达到82.9%,水通量为16.8 L/(m~2·h·MPa).交联后的纳滤膜有良好的耐溶胀性和长期运行稳定性.     

Surface modification of titanium thin film with chitosan via electrostatic self-assembly technique and its influence on osteoblast growth behavior

Chitosan (Chi) and poly (styrene sulfonate) (PSS) were employed to surface modify titanium thin film via electrostatic self-assembly (ESA) technique in order to improve its biocompatibility. The surface chemistry, wettability and surface topography of the coated films with different number of deposited layers were investigated by using X-ray photoelectron spectroscopy (XPS), water contact angle measurement and atomic force microscopy (AFM), respectively. The results indicated that a full surface coverage for the outmost layer was achieved at least after deposition of five layers, i.e., PEI/(PSS/Chi)₂ on the titanium films. The formed multi-layered structure of PEI(PSS/Chi) _x (x ≥ 2) on the titanium film was stable in air at room temperature and in phosphate buffered solution (PBS) for at least 3 weeks. Cell proliferation, cell viability, DNA synthesis as well as differentiation function (alkaline phosphatase) of osteoblasts on chitosan-modified titanium film (PEI/(PSS/Chi)₆) and control sample were investigated, respectively. Osteoblasts cultured on chitosan-modified titanium film displayed a higher proliferation tendency than that of control (p < 0.01). Cell viability, alkaline phosphatase as well as DNA synthesis measurements indicated that osteoblasts on chitosan-modified titanium films were greater (p < 0.01) than those for the control, respectively. These results suggest that surface modification of titanium film was successfully achieved via deposition of PEI/(PSS/Chi) _x layers, which is useful to enhance the biocompatibility of the titanium film.     

Nanostructured carbon nanotubes/copper phthalocyanine hybrid multilayers prepared using layer-by-layer self-assembly approach

In this report, we demonstrate a convenient method of fabricating single-walled carbon nanotubes/organic semiconductor hybrid ultrathin multilayers using a layer-by-layer self-assembly approach. Single-walled carbon nanotubes were solubilized by water-soluble cationic alcian blue pyridine variant and anionic copper phthalocyanine-3,4′,4″,4′″-tetrasulfonic acid tetrasodium salt, which were then utilized for electrostatic layer-by-layer multilayer fabrication. The solubilization ability of single-walled carbon nanotubes was studied in water by UV-vis absorption spectroscopy. The composites were highly dispersed owing to the π-π interactions. In situ surface plasmon resonance spectroscopy during the layer-by-layer multilayer fabrication indicated a stepwise increase in reflectivity, indicating the successive formation of nanostructured hybrid ultrathin films. Cyclic voltammetry revealed that the electroactivity of the hybrid film was enhanced by the incorporation of single-walled nanotubes.     

Surface modification to improve hydrophobicity of detonation nanodiamond

In this work, surface treatment of nanodiamonds (NDs) produced by a detonation technique has been conducted using oleic acid and dodecylamine in order to achieve a stable dispersion in oil. From Fourier transform infrared spectroscopy (FTIR) analyses, it was found that the NDs have various surface functional groups such as -NH2, -COOH, -OH, etc. By inducing covalent bonding between the carboxyl group of oleic acid and the amine group of the ND surface with high chemical reactivity, NDs were well-dispersed in oil for a lengthy period of time. High resolution transmission electron microscopy (HRTEM) images indicate that the surface treatment with oleic acid is highly effective in breaking down the aggregates of NDs into smaller sized particles. The dispersion stabilities of the oils containing as-received NDs and surface treated NDs were compared to each other using Turbiscan measurement.     

Enzyme microcapsules with substrate selective permeability constructed via layer-by-layer polyelectrolyte self-assembly

Polyelectrolyte multilayer microcapsules with entrapped horseradish peroxidase (HRP) have been prepared via a layer-by-layer (LbL) self-assembly strategy of polycation and polyanion on CaCO₃ microparticles as templates. Preparation conditions have been studied and optimized. Within the investigated ranges, use of buffer solutions with lower pH value or lower ionic strength in the buffer solution for polyelectrolyte self-assembly has resulted in thinner polyelectrolyte film and higher permeability of the microcapsules. For dissolving the CaCO₃ templates, use of weakly acidic (pH 4.0) buffer solution in place of routinely used EDTA reagent has improved the catalytic activity of microcapsules. The HRP-containing microcapsules have exhibited catalytic activity to pyrogallol as substrate, while the catalytic activity to 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS) was severely suppressed. No less than 90% of the maximum enzymatic activity to pyrogallol has remained after 30 days. Promising prospects in various biocatalysis applications have been expected for the enzyme microcapsules, due to their selective permeability, stability and reusability.     

Surface modification of titanium for load-bearing applications

Titanium and its alloys are extensively used in load-bearing metallic devices. They are bioinert material and, therefore, get encapsulated after implantation into the living body by a fibrous tissue that isolates them from the surrounding tissues. Here we report modification of titanium surface using bioactive tricalcium phosphates (TCP) and nanoscale TiO2 to enhance cell-materials interaction. We have introduced bioactivity in Ti using laser-assisted coating of TCP and by anodization to grow surface TiO2 at room temperature using a mixed aqueous solution of sodium fluoride, citric acid and sulfuric acid as electrolyte. TCP coating showed a columnar Ti grains at the substrate side of the coating and transitioned to an equiaxed grains at the outside. Coating hardness increased from 882 +/- 67 to 1029 +/- 112 Hv as the volume fraction of TCP increased in the coating. For TiO2 nanotubes, microscopic analysis showed tubes of 50 nm in diameter with wall thickness of 15 nm and typical length between 200 nm and 1 micron based on anodization times. Effects of TCP and nanoscale TiO2 coating on bone cell-material interaction were examined by culturing osteoprecursor cells (OPC1) on coated surfaces. Antibacterial activity analysis using metallic Ag via electrodeposition showed over 99% antibacterial activity against the growth of colonies of Pseudomonas aeruginosa.     

Surface modification of indium-tin-oxide via self-assembly of a donor-acceptor complex: a density functional theory study

The authors study at the density-functional theory level the modification of the electronic structure of the ITO surface upon self-assembly of a monolayer of t-butyl carbazole-substituted phosphonic acid molecules and subsequent p-doping. The results of the calculations point to the existence of two channels for charge transfer. These channels can enhance hole injection between ITO and a hole-transport overlayer through the chemically-modified interface.     

Fabrication of nanofiltration membranes via covalent layer-by-layer self-assembly for charged organic pollutants treatment

Journal of Materials Science - Developing a nanofiltration membrane for organic pollutants is regarded as a significant trial. In this work, composite nanofiltration (NF) membranes were reasonably...     

Surface modification of titanium carbide with carbyne-containing nanocoatings

The aim of this research is to investigate a novel approach to surface engineering of biomaterials that are based on transition metals of the groups IVA-VIA. The approach taken relies on the fact that, during the electropolishing of TiC surfaces, the removal of Ti atoms from the TiC surface surpasses that of C atoms. This leads to enrichment of the TiC surface with carbon. Transmission electron microscopic investigation showed that carbon-based films contain carbynes in the form of nanorod-like clusters with lengths in the range of 5-100 nm. This carbyne-containing layer is 50-100 nm thick. It was generalized that carbyne-containing nanofilms are formed on the carbide surface of transition metals of groups IVA-VIA during electropolishing. Since carbynes, being one-dimensional chain-like structures [(-C identical to C-)n/(=C=C=)n] with sp1 carbon-carbon hybridization, have the highest degree of biocompatibility because of their biological activity, the development of such surface bioengineering with carbynes extends applications of biomaterials based on transition metals of the groups IVA-VIA.