Plasma polymer coatings to aid retinal pigment epithelial growth for transplantation in the treatment of age related macular degeneration

Subretinal transplantation of functioning retinal pigment epithelial (RPE) cells grown on a synthetic substrate is a potential treatment for age-related macular degeneration (AMD), a common cause of irreversible vision loss in developed countries. Plasma polymers give the opportunity to tailor the surface chemistry of the artificial substrate whilst maintaining the bulk properties. In this study, plasma polymers with different functionalities were investigated in terms of their effect on RPE attachment and growth. Plasma polymers of acrylic acid (AC), allyl amine (AM) and allyl alcohol (AL) were fabricated and characterised using X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Octadiene (OD) hydrocarbon films and tissue culture polystyrene were used as controls. Wettability varied from hydrophobic OD to relatively hydrophilic AC. XPS demonstrated four very different surfaces with the expected functionalities. Attachment, proliferation and morphological examination of an RPE cell line and primary RPE cells were investigated. Both cell types grew on all surfaces, with the exception of OD, although the proliferation rate of primary cells was low. Good epithelial morphology was also demonstrated. Plasma polymerised films show potential as cell carrier surfaces for RPE cells in the treatment of AMD.     

Development of a surface to increase retinal pigment epithelial cell (ARPE-19) proliferation under reduced serum conditions

Age related macular degeneration of the eye is brought about by damage to the retinal pigment epithelium (RPE) and is a major cause of adult blindness. One potential treatment method is transplantation of RPE cells grown in vitro. Maintaining RPE cell viability and physiological function in vitro is a challenge, and this must also be achieved using materials that can be subsequently used to deliver an intact cell sheet into the eye. In this paper, plasma polymerisation has been used to develop a chemically modified surface for maintaining RPE cells in vitro. Multiwell plates modified with a plasma copolymer of allylamine and octadiene maintained RPE cell growth at a level similar to that of TCPS. However, the addition of bound glycosaminoglycans (GAGs) to the plasma polymerised surface significantly enhanced RPE proliferation. Simply adding GAG to the culture media had no positive effect. It is shown that a combination of plasma polymer and GAG is a promising method for developing suitable surfaces for cell growth and delivery, that can be applied to any substrate material.     

Improved materials for blood-contacting applications: blends of sulphonated and non-sulphonated polyurethanes

Propyl sulphonate groups were grafted on to the urethane nitrogens of Pellethane 2363-80A at three levels: 1.2, 14, and 50%. Blends with an effective level of 1.2 and 14% were made by blending the 14 and 50% sulphonated polyurethanes with the unsubstituted material. Tensile testing was performed on the materials in both their dry and hydrated state. The blend materials exhibited a small improvement in tensile strength over their bulk analogues. Dynamic contact angle and X-ray photoelectron spectroscopy (XPS) showed an enrichment of sulphonate groups at the surface of the blend materials compared to bulk samples of the same overall composition. Canineex vivo shunt experiments revealed fewer platelets adherent and less platelet spreading on the blend materials than on the bulk materials with the same level of sulphonation. This suggests that sulphonated polyurethanes can be developed that have improved blood compatibility while maintaining good physical properties in an aqueous environment.     

Plasma-modified and polyethylene glycol-grafted polymers for potential tissue engineering applications

Modified and grafted polymers may serve as building blocks for creating artificial bioinspired nanostructured surfaces for tissue engineering. Polyethylene (PE) and polystyrene (PS) were modified by Ar plasma and the surface of the plasma activated polymers was grafted with polyethylene glycol (PEG). The changes in the surface wettability (contact angle) of the modified polymers were examined by goniometry. Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology and electrokinetical analysis (Zeta potential) characterized surface chemistry of the modified polymers. Plasma treatment and subsequent PEG grafting lead to dramatic changes in the polymer surface morphology, roughness and wettability. The plasma treated and PEG grafted polymers were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with PEG increases cell proliferation, especially on PS. The cell proliferation was shown to be an increasing function of PEG molecular weight.     

Montmorillonite clay based polyurethane nanocomposite as substrate for retinal pigment epithelial cell growth

The subretinal transplantation of retinal pigment epithelial cells (RPE cells) grown on polymeric supports may have interest in retinal diseases affecting RPE cells. In this study, montmorillonite based polyurethane nanocomposite (PU-NC) was investigated as substrate for human RPE cell growth (ARPE-19 cells). The ARPE-19 cells were seeded on the PU-NC, and cell viability, proliferation and differentiation were investigated. The results indicated that ARPE-19 cells attached, proliferated onto the PU-NC, and expressed occludin. The in vivo ocular biocompatibility of the PU-NC was assessed by using the HET-CAM; and through its implantation under the retina. The direct application of the nanocomposite onto the CAM did not compromise the vascular tissue in the CAM surface, suggesting no ocular irritancy of the PU-NC film. The nanocomposite did not elicit any inflammatory response when implanted into the eye of rats. The PU-NC may have potential application as a substrate for RPE cell transplantation.     

Ellipsometric studies of antisera binding onto medical polyurethanes immersed in human plasma in vitro

The plasma protein binding properties of four medical polyurethane materials were investigated. The polymers were Pellethane 2363-80AE, ethanol extracted Pellethane, a poly(ether urethaneurea) with a composition similar to Biomer and Containing an acrylic polymer additive, and the same polymer without the additive. The polymers were cast onto silicon wafers and then immersed in human plasma from solution followed by antisera. The deposition of organic material was measured with ellipsometry. All tested polymers displayed low anti-high molecular weight kininogen (-HMWK), anti-Factor XII (-F XII), and anti-fibronectin (-FN) depositions. Polymers containing additives also showed significantly lowered binding of anti-fibrinogen (-FG). The results show that protein binding to the tested polyurethane surfaces were largely modulated by surface active processing aids, and can be conveniently analysed using antisera techniques.     

Fabrication of superhydrophobic TPU film for oil-water separation based on electrospinning route

In this work, we described an electrospinning process for creating superhydrophobic thermoplastic polyurethanes (TPU) mat with bead-on-string morphologies. The initially hydrophobic TPU electrospun film presented superhydrophobic trait after treatment with hydrophobic nanosilicas, which was pre-fabricated by refluxing nanosilicas in a toluene solution of hexadecyltrimethoxysilane (HDTMS). The relationship between the microstructures and wettability was also discussed. This superhydrophobic TPU film turned out to be benign materials for separating oil and water mixture. The development of the electrospun process described in this paper, as well as the extension of our method, will no doubt facilitate the achievement of other functional superhydrophobic films for various applications.     

Experimental research on wetting behavior of refrigerant–oil mixture on micro/nanostructured surface

The wettability of micro/nanostructured surface is a key property for its application in enhancing the boiling heat transfer of refrigerant–oil mixture. The objective of this research is to experimentally investigate the wetting behavior of refrigerant–oil mixture on micro/nanostructured surface. Three types of surfaces including plain copper surface (PS), micro/nanostructured surface (MNS) and micro/nanostructured surface with fluorinated self-assembled monolayer (MNFS) were fabricated; and the wetting behavior of pure R141b as well as R141b-NM56 mixtures with different oil concentrations on three types of surfaces was measured. The experimental results show that the protuberant liquid film is formed during the wetting of refrigerant–oil mixture on MNS or PS, but does not exist on MNFS; the presence of F-SAM or micro/nanostructure modified by F-SAM reduces the surface wettability, while the presence of micro/nanostructure increases the surface wettability; oil increases the wettability of refrigerant on MNS, while it reduces the wettability of refrigerant on MNFS.     

Surface wettability of silicon rubber after irradiation with a glow discharge plasma

Silicon rubber, PDMS, was irradiated by Ar, Ar/H₂ and Ar/O₂ plasmas to increase the surface wettability to water which was found to increase with the irradiation time for every application of plasma irradiation. The use of Ar/O₂ plasma was found to be particularly effective in enhancing the surface wettability. The aging behavior due to exposure to air, ethanol or water was also measured. In the case of continuous exposure to water after plasma treatment, the wettability could be maintained for more than several months with the water immersion.     

等离子体表面技术和在有机材料改性应用中的新进展

综述了20世纪90年代以来低温等离子体表面技术及其在有机材料改性应用中的新进展。介绍阻挡放电和远等离子体处理是实现工业化和获得更好的等离子体表面改性的新方法。目前的研究更多地关注于等离子体接枝表面改性,即将不同性能的单体接枝于用等离子体处理过的材料表面获得永久性表面改性,以提高材料的粘附性、吸湿性、吸附性、导电性和生物相容性等。对低温等离子体表面改性技术的研究和应用进行了展望。     

Electric properties and surface characterization of transparent Al-doped ZnO thin films prepared by pulsed laser deposition

We grew 2 wt.% Al-doped ZnO (AZO) films on 5.08 cm-diameter polymer substrates at room temperature by the pulsed laser deposition (PLD) technique added the beam-rastering function. The structural properties, surface morphology, resistivity, mobility and chemical bonding states of AZO/polymer films were measured. The structuring of polymer surface by atmospheric plasma can occur at nm scales and can influence adhesion, optical and wettability properties of the materials. With increasing plasma treatment power, surface hydrophilicity and roughness for PET and PES polymer increased, respectively.     

Effect of extrusion process melt temperature on polyurethane catheter surfaces

Determination of optimum process melt temperature of medical-grade polyurethane (PU) is an indispensable challenge witnessed during the catheter manufacturing process. This resin does not contain a uniform crystal structure but exists in an amorphous state. The lower shore hardness PU material, used in catheter manufacture, has just a “melt temperature range” instead of a definite melt temperature. This temperature plays a significant role in shaping the catheter surfaces, which directly interact with human tissues and cause health-care-associated issues. The objective of this work is to evaluate the effects of variations in the melt temperature during the extrusion process of medical catheters on their outer surfaces. Medical PU, Pellethane, was used for this study and 12 Fr (4.0?mm) catheters were manufactured with optimal validated parameters, excluding melt temperature. The manufactured catheters were examined under Optical Microscopy and Atomic Force Microscopy (AFM) for surface topography studies. Wettability studies were carried out using a Goniometer for evaluating the water contact angles. The effects of melt temperature on the surface roughness (R_a) and wettability of the catheter surfaces were analyzed through analysis of variance (ANOVA). The conclusion was that the process melt temperature variations have a significant effect on catheter R_a and its wettability characteristics.     

水性聚氨酯的发展、分类、合成及应用

水性聚氨酯是一种环境友好型高分子材料。在概述水性聚氨酯发展历程的基础上，详细阐述了阴离子型、阳离子型、两性离子型、非离子型水性聚氨酯的合成工艺路线、制备方法的优缺点，以及水性聚氨酯的主要应用领域，并指出水性聚氨酯的发展方向。     

Novel robust cellulose-based foam with pH and light dual-response for oil recovery

We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRP. The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose (CE)-based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation (λ > 500 nm). Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation (λ = 365 nm), giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.     

Effect of Heat Treatment Temperature on the Wettability Transition from Hydrophilic to Superhydrophobic on Laser‐Ablated Metallic Surfaces

Superhydrophobic metallic surfaces made via pulsed laser ablation have been utilized recently. Immediately after laser ablation, metallic surfaces become hydrophilic. By aging the laser‐ablated surface in ambient air for a relatively long period of time (several weeks to several months) or using a chemical coating post process, this type of surface becomes superhydrophobic. Herein, a facile post‐process heat treatment that does not use any harsh chemicals is introduced to reduce the wettability transition time from hydrophilicity to superhdyrophobicity compared to surfaces treated for extended periods of time in ambient air. Grid patterns are ablated on aluminum, copper, and titanium by a nanosecond pulsed laser. Then, facile post‐process heat treatment is applied at different temperatures. The effect of temperature on the wettability transition time is studied. The transition time is reduced from several weeks/months to a few hours. The wettability transition mechanism for each metal is also explained. Additionally, several potential applications, such as self‐cleaning, water positioning, and water transport, are proposed.

     

Polymeric meshes for internal sutures with differentiated adhesion on the two sides

The aim of this work is to investigate the effects of different plasma treatments on ePTFE abdominal prostheses with the final goal of obtaining a new prosthesis, made of a single strand of ePTFE, with clearly differentiated adhesion properties on the two sides, which should be able to promote tissue ingrowth on one side and prevent post surgical visceral adhesions on the other.Samples obtained from ePTFE Bard Dulex Meshes have been treated sequentially with three different gases (N₂, O₂ and NH₃) in order to choose the optimal treatment conditions to improve ePTFE wettability. In particular, no modification was induced by N₂ treatment, while the full treatment after the final ammonia gas resulted in the best suitable candidate.As demonstrated by scanning electron microscopy, AFM analyses and contact angle measurements, ammonia plasma treatment increases ePTFE surface roughness and renders it more hydrophilic, thus promoting adhesion without any alteration of the materials bulk properties.The reported results also evidence the possibility to obtain the maximum wettability with a cheap treatment by optimizing plasma exposure time.As a preliminary cell adhesion study, Swiss 3T3 fibroblasts (mouse, embryo) have been seeded on the treated and untreated materials in order to assess whether there was any difference in terms of cell attachment and spreading. Cells seeded on the ammonia plasma treated material showed a better adhesion and spreading when compared to the untreated material.     

Osteoblast cell membrane hybrid bilayers for studying cell-cell interactions

Osteoblast-like cells were grown on a surface that presents cell membrane components to the cells in culture. The culture surface was a bimolecular layer formed by the interaction of osteoblast plasma membrane vesicles with an alkanethiol monolayer. The potential of these osteoblast-membrane hybrid bilayers for promoting osteoblast adhesion, growth and differentiation was examined. UMR-106 osteoblast-like cells cultured on these surfaces are normal in appearance, and in the presence of serum, proliferate as well or better than on control surfaces. The level of alkaline phosphatase production in the presence and absence of serum suggests that the osteoblast-like cells retain their differentiated phenotype, and appear to respond to the cell surface ligands presented by the osteoblast-membrane biomimetic surface. These observations suggest that biomimetic membrane films prepared from osteoblast cell membranes support osteoblast cell growth, allow the cells to maintain their differentiation state and may be suitable as a model system to probe cell-cell interactions.     

Functional Carbon Quantum Dots for Ocular Imaging and Therapeutic Applications

Carbon quantum dots (CDs) are a class of emerging carbonaceous nanomaterials that have received considerable attention due to their excellent fluorescent properties, extremely small size, ability to penetrate cells and tissues, ease of synthesis, surface modification, low cytotoxicity, and superior water dispersion. In light of these properties, CDs are extensively investigated as candidates for bioimaging probes, efficient drug carriers, and disease diagnostics. Functionalized CDs represent a promising therapeutic candidate for ocular diseases. Here, this work reviews the potential use of functionalized CDs in the diagnosis and treatment of eye-related diseases, including the treatment of macular and anterior segment diseases, as well as targeting Aβ amyloids in the retina.     

Polyurethanes for “Two-dimensional” applications

The unsurpassed versatility of polyurethanes is remarkably evident in the areas of two-dimensional applications. Polyurethanes are tailor-made for the wide range of rigid surface coatings, eg; for metal, concrete and wood; for flexible surface coatings; for textile substrates and leather; and for a wide variety of adhesives. Polyurethanes give unexcelled performance in almost all of these applications. In many cases this superiority is achieved by the fact that polyurethanes are generally reactive processing polymers which can be intrinsically cross-linked to the optimal degree. This key fact can be accounted for by the versatility of the NCO group, an “energy package” of unique quality. Two-component polyurethane coatings based on aliphatic polyisocyanates have experienced significant breakthroughs in automotive applications and for powder coatings. A prime target of coating textiles with polyurethanes is the achievement of the quality of natural leather. A highly water vapor permeable, but water repellent textile coating has recently become possible using a direct coating process. The application of a microporous polyurethane film on split leather by a reaction process leads to prime quality leather for shoe uppers. For many years, elastomeric polyurethanes have been the top-ranking adhesives for highly plasticized PVC articles. More recently, polyurethanes have been introduced into the market as structural adhesives, especially for the bonding of automotive body parts. A new principle of heterogeneous cross-linking of polyurethanes which has potential for one-package structural adhesives is presented. Aqueous polyurethane can also be tailor-made for the whole range of two-dimensional applications. They complement the high solids and the powder polyurethane coatings, as well as the solvent-free polyurethane adhesives in the fulfillment of ecological and industrial hygiene requirements.     

Air plasma treatment of copper sheets using Diffuse Coplanar Surface Barrier Discharge

The treatment of copper sheets by atmospheric-pressure air plasma generated using the Diffuse Coplanar Surface Barrier Discharge was studied. The surface free energy measurements indicated a significant increase of the wettability after several seconds of plasma exposure. The atomic force microscopy technique revealed a relatively small increase of the surface roughness due to the plasma treatment. The observed increase of wettability, the influence of air humidity on treatment efficiency and the hydrophobic recovery of the plasma treated surfaces were studied by the x-ray photoelectron spectroscopy. A generation of surface -NO_x groups in humid air plasma was observed.