Phosphorylated gelatin to enhance cell adhesion to titanium

Phosphorylated gelatin was prepared for surface modification of titanium to enhance cell attachment. The modified gelatin was synthesized by coupling gelatin with phosphonobutyric acid with water‐soluble carbodiimide. Circular dichroism revealed no significant change in the gelatin as a result of phosphorylation. The binding behavior of phosphorylated gelatin on the titanium surface was observed by quartz crystal microbalance. The modified titanium surface was analyzed by measuring the water contact angle. Enhancement of the attachment of osteoblast cells MC‐3T3L1 was observed on the phosphorylated‐gelatin‐modified titanium. Phosphorylation of gelatin was effective for preparation of a cell‐adhesive titanium surface. © 2013 Society of Chemical Industry     

Wettability and microstructure of polymer surfaces: stereochemical and conformational aspects

Stereoregular poly(methyl methacrylates) (PMMAs) solvent-cast in the form of films against a glass substrate were employed as model systems for a systematic study of the relationship between the molecular structure (as characterized by the stereochemistry and conformations of macromolecules), the functional-group composition, and the wettability of polymer surfaces. The water wettability of a syndiotactic surface was found to be highly sensitive to the polarity of the adjacent phase in the film-casting process, whereas the wettability of an isotactic surface was invariant to the polarity of the contacting medium. The tacticity-dependent wetting behavior arises from the difference in the extent of functional-group surface segregation or, in other words, from the different surface activity of the different tactic versions of the polymer. This difference, in turn, is associated with fundamental distinctions in the conformational structures energetically allowed for the isotactic and syndiotactic configurations of the polymer chain; the syndiotactic macromolecule is capable of adopting an amphiphilic surface conformation, whereas the energetically allowed conformational structures of the isotactic macromolecule do not possess amphiphilic character. In view of these findings, the isotactic surfaces can be regarded as 'ideal' model surfaces for research on the fundamentals of wetting phenomena. In addition, there is evidence for failure of the basic assumption of the Cassie approach, i.e. the assumption of macroscopic chemical heterogeneity, to describe adequately the wetting behavior of isotactic PMMA surfaces.     

Propylene polymerization using MgCl2/ethylbenzoate/TiCl4 catalyst: Determination of titanium oxidation states

The chemical interaction of the catalyst MgCl₂/ethylbenzoate/TiCl₄ with the cocatalysts triethylaluminum and trisobutylaluminum was investigated to establish a relationship between the titanium oxidation states and the catalytic activity, polymer isotacticity, and polymer molecular weight in propylene polymerizations. This interaction was studied using different Al : Ti molar ratios by measuring the changes of the titanium oxidation states at different polymerization times. Both hydrogen and alkyl aluminum caused a reduction of Ti⁴⁺ species to lower oxidation states species Ti³⁺ and Ti²⁺. However, the Ti⁴⁺ species reduction appeared to be incomplete. It was found that the Ti⁴⁺ species undergoes a severe reduction as the Al : Ti molar ratio increases from 50 to 230 as overreduction takes place. This change of the Ti³⁺ species percentage with time was found to correlate with the rate–time profiles of propylene polymerization. From this observation, it would be fair to conclude that the trivalent titanium species is more likely to be the active titanium species for propylene polymerization than the aforementioned catalyst system. On the other hand, hydrogen addition was found to cause an increase in Ti³⁺ species. The increases in both hydrogen amount and/or Al : Ti molar ratio were found to cause a decrease in both molecular weight and polypropylene isotactic index. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 56–62, 2004     

Study on the adhesion behaviour of oil droplets in water on solid surfaces with different wettability and inclination

Microscopic adhesion of oil droplets is a hot research topic within multiphase flow systems in the petrochemical field in recent years, and it is also the key to revealing the mechanism of oil droplet–wall interaction. In this paper, a high-speed camera was used to capture the dynamic process of oil droplets impacting stainless steel, polyethylene, brass, and other materials in water, deeply analyze the influence mechanism of material wettability, droplet size, and inclination on adhesion behaviour in this process, and draw the Re~θ_eq phase diagram. The experimental results show that properly enhancing the lipophilicity of the material can prolong the drainage time and effectively inhibit adhesion. Too much lipophilicity can dramatically shorten the drainage time instead, which easily leads to the rapid adhesion of oil droplets. An increase in droplet size can also prolong the drainage time; at Re ≥46.31, the excessive initial kinetic energy is consumed in the form of oil droplet rebound, which is not conducive to adhesion, and the more lipophilic the material is, the more significant the rebound effect. In addition, although an increase in the inclination can inhibit oil droplet bounce off, it also decreases the wall restraint to oil droplets, resulting in lateral and normal displacements, which greatly increases the drainage time. The findings can facilitate the understanding of oil droplet–wall interaction and provide a scientific basis for the design and development of efficient separation equipment and the optimization of the low-temperature gathering and transportation of high water-bearing crude oil.     

Electrochemical oxidation of ethanol in acid media on titanium nitride supported fuel cell catalysts

In the present study, titanium nitride, TiN that possesses good electronic conductivity, high corrosion resistance combined with the ability to support metallic particles, has been used to anchor Pt catalysts and subsequently used for ethanol oxidation. Platinum deposited on TiN (Pt–TiN) surface is contrasted with the conventional support material, Vulcan carbon for the electrochemical oxidation of ethanol in acidic medium. Though the comparison is not straight forward due to different morphology/particle size of the Pt catalyst on the two supports, the present investigations reveal that the TiN support lead to surface Ti–OH type functional groups that help in reducing the accumulation of carbon monoxide on the catalyst surface. The Tafel slopes are similar but the exchange current density on Pt–TiN is approximately twice that of the value observed on Pt–C. X-ray photoelectron spectroscopy data support the long term stability and electrocatalytic activity of Pt–TiN electrocatalyst.     

Photoactivatable caged cyclic RGD peptide for triggering integrin binding and cell adhesion to surfaces

We report the synthesis and properties of a photoactivatable caged RGD peptide and its application for phototriggering integrin- and cell-binding to surfaces. We analysed in detail 1) the differences in the integrin-binding affinity of the caged and uncaged forms by quartz crystal microbalance (QCM) studies, 2) the efficiency and yield of the photolytic uncaging reaction, 3) the biocompatibility of the photolysis by-products and irradiation conditions, 4) the possibility of site, temporal and density control of integrin-binding and therefore human cell attachment, and 5) the possibility of in situ generation of cell patterns and cell gradients by controlling the UV exposure. These studies provide a clear picture of the potential and limitations of caged RGD for integrin-mediated cell adhesion and demonstrate the application of this approach to the control and study of cell interactions and responses.     

Reversible Switching of Surface Wettability and Water Adhesion on a Polymer Nano-composite Coating

Abstract

Super-hydrophobic polymer/ZnO nano-composite coatings were fabricated by a simple spray-coating method. When the prepared super-hydrophobic coating was directly illuminated by UV light, the surface was fully covered with the hydrophilic groups, which created a state of super-hydrophilic wettability. When UV light illuminated the surface through a mask, the surface maintained its super-hydrophobic property, but the adhesion of a water droplet changed from sliding easily to a highly sticky movement. More importantly, the initial surface wettability and water adhesion can be re-established by heat treatment, and these processes were repeated, with full reproducibility, for a number of cycles.     

医用钛合金微弧氧化膜的制备及其生物相容性研究

利用微弧氧化技术在Ti合金表面制备了医用羟基磷灰石(HA)膜,研究了HA膜在模拟体液中的生物相容性,通过SEM观察了HA膜在模拟体液中浸泡不同时间的表面形貌,并利用EDs测试了HA膜浸泡前后的Ca、P原子分数.结果表明,HA膜在模拟体液中浸泡后,体液的pH变化不大,而经过溶解-重结晶,新生成的HA晶粒发育更完整,更利于...     

Fabrication and application of superhydrophilic surfaces: a review

Extreme wetting behaviors have been the subject of numerous studies in recent decades. Superhydrophilic surfaces with water contact angle lower than 5° is one of the most exciting research areas which has attract much attention. The ultrafast drying of such surfaces can provide outstanding properties such as antifogging, evaporative cooling, self-cleaning, and others. We review here the basic strategies and recent progress in fabricating superhydrophilic surfaces. And smart surfaces combining superhydrophilic and superhydrophobic abilities are highlighted, including surfaces with stimuli reversible wettability, patterning wettability, and gradient wetting. We also provide insights into the applications of the highly wettable surfaces, especially in devising new potentials.     

基于神经网络的钛合金微弧氧化膜层性能预测模型的建立

采用微弧氧化技术在钛合金表面制备了陶瓷膜层。利用正交试验得到了不同工艺参数(电流密度、频率、占空比和氧化时间)与膜层性能(厚度、粗糙度和显微硬度)数据,借助MATLAB软件建立了由4个输入向量、13个隐含层节点和3个输出向量组成的BP人工神经网络模型。该网络能较好地掌握工艺参数与膜层性能之间的内在规律,并能高精度预测膜层的性能,3个性能参数的平均预测误差分别为4.1%、4.2%和2.4%,最大预测误差分别为8.2%、8.6%和3.1%。     

Selective oxidation of secondary amines over titanium silicalite molecular sieves,TS-1 and TS-2

Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H₂O₂ lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group.     

Surface modifications of the titanium mesh for cranioplasty using selenium nanoparticles coating

The aim of this study was to made and characterized a nanostructured surface on titanium mesh for cranioplasty, by adhesion of selenium nanoparticles (SeNPs) in situ, in a hydrothermal reaction. The structural characterization of selenium nanoparticles was performed using DLS and TEM, revealing that the size and morphology of nanoparticles depends on the nature of saccharide reducing agent. In situ hydrothermal reaction revealed that selenium nanoparticles adherence on titanium mesh surface had the best result in the case of starch-derived SeNPs, as demonstrated by SEM/EDX analysis. In vitro hemolysis and RBC osmotic fragility tests suggest that nanostructured surface created upon SeNPs adhesion doesn’t induce damage to RBC membrane; the hemolysis values indicated a good biocompatibility especially in the case of titanium specimens modified with starch-derived SeNPs. Moreover, the nanostructured surface clearly offers the desired biological response of human fibroblasts cells. The proposed improvement of the surfaces in the case of titanium mesh for cranioplasty may offer important benefits in terms of osteointegration, without using additional screws for fixation and closure procedure.     

钛硅分子筛的改性对环己烷氧化反应的影响

使用不同改性液H_2SO_4-H_2O_2、(NH_4)_2CO_3-H_2O_2、(NH_4)HF_2-H_2O_2和(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2混合溶液对中空钛硅分子筛进行改性。采用XRD、UV-Vis和拉曼光谱进行表征分析,考察改性前后钛硅分子筛在环己烷氧化反应的催化性能。结果表明,改性过程没有破坏钛硅分子筛的MFI拓扑结构,但提高了钛硅分子筛相对结晶度,并脱除了部分锐钛矿相TiO_2;与未改性钛硅分子筛相比,环己醇和环己酮选择性及H_2O_2有效利用率明显提高,以改性液(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2改性钛硅分子筛效果最佳,醇酮选择性提高12.78个百分点,H_2O_2有效利用率提高17.33个百分点;(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2混合溶液改性钛硅分子筛显著降低H_2O_2用量,在己内酰胺生产过程中有很好的应用前景。     

On oxidation and adhesion of copper‐filled PE

The IR‐spectroscopy and MVCIR technique were used to study the role of technological factors (filler content, film thickness) in oxidation of polyethylene coatings filled with copper powder. It was learned that copper powder introduced into polyethylene reduces the ultimate level of oxidation of both the outer surface layer and deep‐seated layers of the polymer; also, the layer thickness of the specimens oxidized at diffusion conditions was observed to be decreased. Besides, the oxidation gradient determined through the specimen thickness was decreased on increasing the filler content. For example, with copper concentration over 3 vol %, the ultimate level of oxidation within the polymer layer that undergoes diffusive oxidation remains unchanged. The filler exerts its influence on bonding of the coatings, first of all through variations in the oxidation level of the polymer layer bordering on the substrate. For example, at the filler concentration above 3 vol %, the achievable level of adhesional strength does not depend on the coat thickness (the coat thickness being smaller than that of the diffusively oxidized layer). In thicker coatings, oxidative transformations do not, in fact, take place in the zone of adhesional contact, and the adhesion strength remains unchanged during thermal treatment. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2047–2052, 2001     

氯化法钛白生产工艺中四氯化钛氧化微观反应机理研究进展

氯化法是国际上生产高档金红石钛白的主要方法,具有产品质量好、环境污染小、自动化程度高、综合能耗低等优点,在钛白生产领域具有很高的应用价值和发展前景,但对于四氯化钛的氧化反应机理却尚未明确,因此探明四氯化钛氧化反应机理已成为氯化法钛白生产技术的研发重点。本文从表观反应机理、微观反应机理角度论述四氯化钛氧化反应机理研究概况,并对二氧化钛的气相成核、晶核表面生长及三氯化铝的作用机制等研究进展进行分析,展望四氯化钛微观氧化反应机理的研究方向。最后指出,四氯化钛氧化反应机理的研究对氧化反应器的放大设计、产品的形态控制、避免结疤等工业生产具有重要指导意义。     

添加剂铬酸钾对TC4钛合金微弧氧化膜层性能的影响

以TC4钛合金为基体,在硅酸钠电解液中进行微弧氧化(MAO)。电解液的主要成分为Na2SiO3、Na3PO4和NaOH,工艺条件为:电压450V,频率500Hz,占空比30%,时间5min。通过向电解液中添加0.5g/LK2CrO4对微弧氧化膜层进行着色。采用涡流测厚仪、维氏硬度计、扫描电镜、X射线荧光光谱分析仪以及中性盐雾试验等,研究了K2CrO4添加剂对膜层厚度、显微硬度和形貌等性能的影响。结果表明,所得微弧氧化膜层为典型的不规则多孔氧化物陶瓷膜层,显微硬度和耐蚀性明显优于基材。在电解液中加入K2CrO4后,MAO膜层由灰色转变为深黄色;K2CrO4使膜层粗糙度和孔径增大,与基体结合处的缺陷减少,结合力增强;膜层的脆性和内应力降低,耐蚀性增强。     

The effects of thermoresponsive microgel density on cell adhesion,proliferation, and detachment

In recent years, poly(N-isopropylacrylamide)-based microgels have been emerged as a new thermoresponsive coating for cell/cell sheet harvesting, yet few work reports their effect on cell attachment, morphology, activity, and proliferation in details. In this work, poly(N-isopropylacrylamide-co-styrene) (pNIPAAmSt) microgel was selected as the model to study its density on NIH3T3 cell adhesion, morphology, activity, and detachment. Results showed that 0.5 wt % pNIPAAmSt microgel density leads to more cells adhesion, higher cell activity yet lower cell proliferation. Moreover, cell adhesion location can be well controlled either by manipulating the sub-cellular scale distances between microgels or by fabricating large scale surface patterns of the microgels on higher microgel density. By temperature stimuli, similar ratio cells detached from the microgel density surface from 0.5 to 1.5 wt %. The results in this article are worthy for the application of thermoresponsive microgels in cell regulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48773.     

电压和氟化钠浓度对钛合金阳极氧化膜性能的影响

在3 g/LNaOH溶液中加入NaF添加剂作为电解液,研究了电压和添加剂浓度对钛合金板表面氧化膜的颜色、硬度和耐腐蚀性的影响,分析了氧化膜的扫描电镜图和X射线衍射图.结果表明:电压是影响阳极氧化膜性能的主要参数,电压和NaF浓度的变化都能引起氧化膜颜色、硬度、耐腐蚀性以及表面形貌等的改变.     

The effect of topography and wettability of biomaterials on platelet adhesion

In this study, the effect of surface topography and wettability on the adsorption of albumin, fibrinogen, and platelet was investigated. In this experiment, silicon substrate with hydrophobic treatment, which has a micron-scale pillar structure was used. The proteins used were bovine serum albumin (BSA) and bovine fibrinogen (BFg), and platelet used was from human blood. BSA was fluorescently labeled with fluorescein isothiocyanate and BFg was fluorescently labeled with rhodamine B isothiocyanate. The experiment was conducted under shear flow condition, just like human blood vessels flow. In this study, BSA was preferentially adsorbed on hydrophobic surface, however BFg was adsorbed more on the hydrophilic surface. Fewer platelets were adhered on the hydrophobic surface. The lowest fibrinogen adsorption amount and the lowest platelet activity was observed on surfaces with specific interspacing of 6–8 μm, and BSA adsorption peaks at the height of 12 μm.The results shows that the hydrophobic surface has good anti-thrombogenicity and blood compatibility. Moreover, a surface with the characteristic scale similar to the platelet size is capable of inbibiting platelet adhesion and activation.