共查询到20条相似文献,搜索用时 15 毫秒
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Pol Cabanach Abdon Pena-Francesch Devin Sheehan Ugur Bozuyuk Oncay Yasa Salvador Borros Metin Sitti 《Advanced materials (Deerfield Beach, Fla.)》2020,32(42):2003013
Microrobots offer transformative solutions for non-invasive medical interventions due to their small size and untethered operation inside the human body. However, they must face the immune system as a natural protection mechanism against foreign threats. Here, non-immunogenic stealth zwitterionic microrobots that avoid recognition from immune cells are introduced. Fully zwitterionic photoresists are developed for two-photon polymerization 3D microprinting of hydrogel microrobots with ample functionalization: tunable mechanical properties, anti-biofouling and non-immunogenic properties, functionalization for magnetic actuation, encapsulation of biomolecules, and surface functionalization for drug delivery. Stealth microrobots avoid detection by macrophage cells of the innate immune system after exhaustive inspection ( > 90 hours), which has not been achieved in any microrobotic platform to date. These versatile zwitterionic materials eliminate a major roadblock in the development of biocompatible microrobots, and will serve as a toolbox of non-immunogenic materials for medical microrobot and other device technologies for bioengineering and biomedical applications. 相似文献
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Hsiang‐Chieh Hung Priyesh Jain Peng Zhang Fang Sun Andrew Sinclair Tao Bai Bowen Li Kan Wu Caroline Tsao Erik J. Liu Harihara S. Sundaram Xiaojie Lin Payam Farahani Timothy Fujihara Shaoyi Jiang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(31)
Medical devices face nonspecific biofouling from proteins, cells, and microorganisms, which significantly contributes to complications and device failure. Imparting these devices with nonfouling capabilities remains a major challenge, particularly for those made from elastomeric polymers. Current strategies, including surface coating and copolymerization/physical blending, necessitate compromise among nonfouling properties, durability, and mechanical strength. Here, a new strategy is reported to achieve both high bulk mechanical strength and excellent surface nonfouling properties, which are typically contradictory, in one material. This is realized through a nonfouling polymeric elastomer based on zwitterionic polycarboxybetaine derivatives. By hiding both charged moieties of the zwitterionic compounds with hydrocarbon ester and tertiary amine groups, the bulk polymer itself is elastomeric and hydrophobic while its superhydrophilic surface properties are restored upon hydrolysis. This coating‐free nonfouling elastomer is a highly promising biomaterial for biomedical and engineering applications. 相似文献
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Paladini F Pollini M Talà A Alifano P Sannino A 《Journal of materials science. Materials in medicine》2012,23(8):1983-1990
The growing resistance of many strains of bacteria to antibiotics and antiseptics is becoming a serious problem in medicine. Nano-silver is one of the most prominent products in medicine because it exhibits unusual physicochemical properties and a strong biological activity. In this work an innovative silver deposition technology was applied to temporary polyurethane catheters for haemodialysis. The working conditions of catheters were reproduced through laboratory equipment that ensured the flow of deionized water and simulated body fluid inside the lumina at corporeal temperature. The growth and the adhesion of Staphylococcus aureus on the surface of the device were studied through fluorescence microscopy. ICP-AES was adopted to calculate the amount of silver released from the substrate. The stability of the coating during the whole working life of the device was demonstrated through thermo-gravimetric analysis. 相似文献
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《Composites Part A》1999,30(9):1039-1044
In order to improve the interfacial adhesion and impact properties of ultra-high modulus polyethylene (UHMPE) fiber/epoxy composites at the same time, the fiber coating technique was combined with the oxygen plasma treatment. The UHMPE fiber was treated with oxygen plasma and thin polybutadiene (PB) coating was introduced. PB coating decreased the interfacial adhesion and increased the impact property of the oxygen-plasma-treated UHMPE fiber/epoxy composites. However, oxygen-plasma-treated and PB-coated UHMPE fiber/epoxy composites show improved interfacial adhesion, flexural properties and impact property in comparison with the untreated control UHMPE fiber/epoxy composites. Oxygen plasma treatment introduces micro-pittings on the UHMPE fiber surface. These micro-pittings improved interfacial adhesion and flexural properties and decreased impact properties through mechanical interlocking. Thin PB coating cannot exclude this mechanical interlocking effect completely and there are imperfect wetted UHMPE fiber surface regions in which effect mechanical interlocking can occur. Stress transfer through the viscous PB interlayer also contributes to the interfacial adhesion and flexural properties of PB-coated UHMPE fiber/epoxy composites. The impact property of PB-coated UHMPE fiber/epoxy composites is due to low modulus PB interlayer. 相似文献
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Superdurable Coating Fabricated from a Double‐Sided Tape with Long Term “Zero” Bacterial Adhesion 下载免费PDF全文
There is no coating technology currently available to prevent the notorious biofilm formation issue. Here, a potential solution to fully address this tough issue is reported by developing a super‐antifouling coating. The use of zwitterionic hydrogel (a double‐sided tape) and commercial superglue is combined and a durable and ultrarobust antifouling zwitterionic (DURA‐Z) coating is created that can be easily and universally applied on common substrates. Commercial superglue mostly for binding hydrophobic materials is used to strongly immobilize the superhydrophilic DURA‐Z coating through interpenetration. DURA‐Z coating effectively solves several key challenges preventing the current antifouling coatings from practical use, including difficult fabrication, low efficacy, poor toughness, and durability. The fabricated DURA‐Z coating retains antifouling property after 90 d of immersion in water, 50 d of buffer shearing, and 30 d of water flushing, and after repeated knife scratch and sandpaper abrasion under 570 kPa. The DURA‐Z coating achieves a rarely reported long‐term biofilm resistance to both Gram‐positive and Gram‐negative bacteria and fungi: it remains almost “zero” microbe adhesion after continuously challenged by more than 109 cells mL?1 culture medium for 30 d. 相似文献
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Adhesion strength and fracture toughness are two crucial mechanical properties for bioceramic coatings on metal implants directly affecting successful implantation and long-term stability. In this study, the adhesion strength of sol-gel derived FHA coatings on Ti6Al4V substrates was measured by pull-out tensile test, and the toughness was assessed by energy release method. With increase of the degree of fluoridation, the adhesion strength increases up to about 40% and the fracture toughness increases about 200 to 300%. Contrary to the wide-spread belief, it is interesting to note that after soaking in the Tris-buffered physiological saline solution (for 21 days), the adhesion strength increases about 60% as compared with the as-deposited coating, instead of decreasing. The mechanism of the increase is discussed. 相似文献
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Rapid re-endothelialization at an atherosclerotic lesion after stent employment is essential for reducing or preventing local
thrombus formation and restenosis. To prevent these complications via enhanced rapid re-endothelialization, poly n-butyl methacrylate (PPBMA) coating was deposited on the stent surface through a radio-frequency plasma polymerization process,
with oxygen as the carrier gas. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS)
characterization confirmed the occurrence of the plasma polymerization and the chemistry properties of the PPBMA. Scanning
electron microscopy (SEM) revealed a smooth and dense surface. The wettability of the polymeric films measured by the contact
angle indicated that the surface was more hydrophilic (2.0 ± 1°) than the original surface (24 ± 1°) by the introduction of
the PPBMA coating, with a slight decrease even after 4 days. The results of the culture of human umbilical cord veins endothelial
cells (HUVEC) in vitro showed that compared with the control of 316L stainless steel, the attachment and growth of cells on
the PPBMA-coated surface was significantly enhanced, and a confluent endothelial cells layer was formed after a 4-day culture.
A platelet adhesion experiment revealed that the blood compatibility of the substrate surface after PPBMA deposition was also
obviously improved. The PPBMA coating remained intact on the stent surface after expansion according to the clinic protocol,
indicating that the adhesive strength of PPBMA coating was high enough to withstand the external force in the process of stent
expansion. This in vitro pilot study prior to in vivo experiments suggested that this plasma PPBMA was promising for coating
stent materials for rapid re-endothelialization. 相似文献
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Xingyu Chen Zaifu Lin Ying Feng Hong Tan Xinyuan Xu Jun Luo Jianshu Li 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(42)
Biodegradable polycaprolactone (PCL) has been widely applied as a scaffold material in tissue engineering. However, the PCL surface is hydrophobic and adsorbs nonspecific proteins. Some traditional antifouling modifications using hydrophilic moieties have been successful but inhibit cell adhesion, which is not ideal for tissue engineering. The PCL surface is modified with bioinspired zwitterionic poly[2‐(methacryloyloxy)ethyl choline phosphate] (PMCP) via surface‐initiated atom transfer radical polymerization to improve cell adhesion through the unique interaction between choline phosphate (CP, on PMCP) and phosphate choline (PC, on cell membranes). The hydrophilicity of the PCL surface is significantly enhanced after surface modification. The PCL‐PMCP surface reduces nonspecific protein adsorption (e.g., up to 91.7% for bovine serum albumin) due to the zwitterionic property of PMCP. The adhesion and proliferation of bone marrow mesenchymal stem cells on the modified surface is remarkably improved, and osteogenic differentiation signs are detected, even without adding any osteogenesis‐inducing supplements. Moreover, the PCL‐PMCP films are more stable at the early stage of degradation. Therefore, the PMCP‐functionalized PCL surface promotes cell adhesion and osteogenic differentiation, with an antifouling background, and exhibits great potential in tissue engineering. 相似文献
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薄膜结合强度的刮剥式测量方法 总被引:2,自引:0,他引:2
本文介绍了一种薄膜结合强度的新型测量方法~刮剥法的测量原理、特点以及应用范围。所谓薄膜结合强度的刮剥式测量方法(简称刮剥法),实际上是一个使用特制刮剥刀具、以类似于薄层金属刮削方式工作,并以从基底上剥离薄膜所需能量作为其结合强度量度的测量方法。刮剥法与现广泛使用的划痕式结合力测量法的区别主要表现为:(1)该法是一个能量测量方法,即以薄膜的剥离能量作为薄膜与基体的结合强度的描述;(2)测量时采用的是对膜/基界面的切向加载方式;(3)测量结果是对膜/基结合强度的直接描述,并对基底表面状态、材质等不敏感;(4)可以对其它方法无法进行测量的超硬材料薄膜,如金刚石和立方氮化硼等,进行结合强度测量。本文通过对刮剥过程中刮剥刀刃附近区域的受力分析,得出了成功实现沿界面剥离薄膜的必要条件以及刮剥法测试对试样的要求和应用范围。 相似文献
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The interfacial adhesion between wood fiber and thermoplastic matrix polymer plays an important role in determining the performance of wood-polymer composites. The objectives of this research were to elucidate the interaction between the anhydride groups of maleated polypropylene (MAPP) and hydroxyl groups of wood fiber, and to clarify the mechanisms responsible for the interfacial adhesion between wood fiber and polypropylene matrix. The modification techniques used were bulk treatment in a thermokinetic reactive processor and solution coating in xylene. FT-IR was used to identify the nature of bonds between wood fiber and MAPP. IGC and wood veneer pull-out test was used to estimate the interfacial adhesion. Mechanical properties of injection molded woodfiber-polypropylene composites were also determined and compared with the results of esterification reaction and interfacial adhesion tests. Confocal Microscopy was employed to observe the morphology at the wood fiber-polypropylene interface, and the dispersion and orientation of wood fiber in the polypropylene matrix, respectively. The effectiveness of MAPP to improve the mechanical properties (particularly the tensile strength) of the composites was attributed to the compatibilization effect which is accomplished by reducing the total wood fiber surface free energy, improving the polymer matrix impregnation, improving fiber dispersion, improving fiber orientation, and enhancing the interfacial adhesion through mechanical interlocking. There was no conclusive evidence of the effects of ester links on the mechanical properties of the composites. 相似文献
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氧化锆陶瓷具有良好的力学性能和生物相容性, 是一种应用前景广阔的硬组织植入体材料。为促进植入体与骨组织形成稳定的骨结合, 本研究利用等离子喷涂制备了氧化锆增韧的锶、硅、氟微量掺杂羟基磷灰石(ZrO2-DHA)涂层, 对涂层物相、形貌以及力学性能和体外生物学性能进行了研究。结果表明, 锶、硅、氟的共掺杂通过成骨分化的信号转导通路提高了羟基磷灰石涂层对成骨细胞的黏附和分化等生物学性能; 不同复合组分的ZrO2-DHA涂层均不同程度地促进了小鼠成骨前体细胞的细胞活力和成骨分化相关基因的表达。在细胞培养的第7 d, DHA含量为70%的ZrO2-DHA涂层(7DHA) Alp和Col-I的相对表达量分别是对照组的约2.8倍和2.3倍; ZrO2-DHA涂层的力学性能随氧化锆组分的增加而增强, DHA涂层和7DHA涂层的硬度和结合强度分别为250.8、313HV和25.1、31.8 MPa; 7DHA涂层中的交织网络结构, 对残余热应力、压应力和拉伸力的承受能力较DHA涂层明显提升, 满足植入体应用需求。 相似文献
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Nilsson S Svedberg TM Pettersson J Björefors TF Markides K Nyholm L 《Analytical chemistry》2001,73(19):4607-4616
The processes that cause the failure of sheathless electrospray ionization (ESI) emitters, based on different kinds of gold coatings on fused-silica capillaries, are described and explained. The methods chosen for this study include electrochemical methods, ICPMS analysis of the electrolytes used, SEM studies, and electrospray experiments. Generally, the failure occurs by loss of the conductive coating. It is shown that emitters with sputter-coated gold lose their coatings because of mechanical stress caused by the gas evolution accompanying water oxidation or reduction. Emitters with gold coatings on top of adhesion layers of chromium and nickel alloy withstand this mechanical stress and have excellent durability when operating as cathodes. When operating as anodes, the adhesion layer is electrochemically dissolved through the gold film, and the gold film then flakes off. It is shown that the conductive coating behaves as a cathode even in the positive electrospray mode when the magnitude of a superimposed reductive electrophoretic current exceeds that of the oxidative electrospray current. Fairy-dust coatings developed in our laboratory (see Barnidge, D. R.; etal.Anal. Chem. 1999, 71, 4115-4118,) bygluing gold dust onto the emitter, are unaffected by the mechanical stress due to gas evolution. When oxidized, the fairy-dust coatings show an increased surface roughness and decreased conductivities due to the formation of gold oxide. The resistance of this oxide layer is however negligible in comparison with that of the gas phase in ESI. Furthermore, since no flaking and only negligible electrochemical etching of gold was found, practically unlimited emitter lifetimes may be achieved with fairy-dust coatings. 相似文献
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Surfactants such as didodecyldimethylammonium bromide (DDAB) adsorb onto fused-silica capillaries to form semipermanent bilayer coatings. However, such coatings must be regenerated between runs to maintain efficiency and reproducibility. In this paper, chemical and physical factors affecting the stability of DDAB coatings are investigated. Chemical factors such as ionic strength and the nature of the buffer anion (e.g., from acetate to phosphate), which decrease the critical micelle concentration of DDAB, improve the coating stability. Increasing buffer pH also increases the coating stability. Finally, reducing the capillary diameter and reducing the volume of buffer flushed through the capillary enhance the coating stability. Using 50 mM acetate, pH 5.0, in a 25-microm-i.d. capillary, cationic proteins were separated with efficiencies of 1.05 million plates/m and a run-to-run migration time reproducibility of 0.6-0.8% RSD for 10 successive runs without regeneration of the DDAB coating between runs. 相似文献
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H. Hamatani Y. Ichiyama J. Kobayashi 《Science and Technology of Advanced Materials》2013,14(4):319-326
The objective of the present study is to develop multi-functioned coating to the components, which are made of copper with electroplated Ni and are widely used for steel making industry. In this paper, we report the mechanical and thermal properties of Ni based superalloys with carbide sprayed by high velocity oxygen fuel (HVOF), and the detailed effects of sprayed material, spraying conditions, and initial powder structure on these properties. It was found that, among commercial Ni self-fluxing alloys (without fusing treatment), coating with a carbon content of 0.58 mass% had the most preferable properties, with a good balance of the hardness, strength, and thermal shock resistance. The thermal shock resistance depended not only on the strength of the coating but also on the volume contraction when tested at high temperatures. For the several developed Ni based superalloys with carbide, Ni20Cr8Mo5Fe–WC and Ni16Cr15Mo3–WC demonstrated the prominent adhesion strength and thermal shock resistance with high Galvanic corrosion resistance through optimized spraying condition. Also, 20 mass% NiCr–Cr3C2 coating sprayed by using employed relatively small primary particle succeeded in achieving the multi-superior properties; high adhesion strength, high corrosion resistance and thermal shock resistance. 相似文献
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《Materials Letters》2006,60(21-22):2627-2632
In order to prepare densely packed hydroxyapatite (HAp) coating onto titanium substrate through electrophoretic deposition (EPD), it is highly desirable to produce stable HAp suspension. In this study, nano-HAp particles prepared by hydrothermal method were employed for EPD. The stability of HAp suspensions in various primary aliphatic alcohols (C1–C4) has been studied by measurement of sedimentation tests and electricity conductivity. Furthermore, to make a stable suspension, a dispersant [triethanolamine (TEA)] was added. Maximum stability is observed for the suspension containing n-butanol as the dispersion medium and TEA as the dispersant. The HAp coating deposited in this suspension was observed to be a crack-free and densely packed coating through scanning electron microscopy examination. The shear strength and nano-indention tests have confirmed the good adhesion between the coating and the substrate. 相似文献