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www.springerlink.com; International audience; We report a method to obtain biocompatible PEG copolymer coatings inside High Density Polyethylene (HDPE) and Pyrex tubes, which was successfully developed by using a transporting discharge. The latter being a dry process, it is easier to apply as compared to the conventional multistep wet chemical techniques. The results presented in this paper show that for a 70 cm tube good cell repellent properties as compared to the control was obtained for the entire length of the tube. The best nonfouling properties with respect to CT-26 (colon cancer) were obtained for coatings presenting the best retention of ether functionalities from the DEGME monomer i.e. between 5-25 cm downstream of the tube. These results are interesting for surface modification of biomaterial and biomedical devices which present hollow bodies.

International audience; A low pressure ICP plasma setup was utilized to deposit thin organic barrier coatings on various substrates to fabricate DDS with encapsulated Carboplatin as a drug and Methylene Blue as a drug model. Choice of the substrates and optimal plasma parameters were discussed for the fabrication of DDS with required characteristics. Prepared thin films were analysed by FTIR, SEM, and the barrier properties were studied by measuring drug concentration released into the medium by UV-VIS and ICP-MS techniques.

In this work, an open-air arc plasma jet has been studied to polymerize 3-aminopropyelthrietoxysilane (APTES), which is the most commonly used aminosilane to functionalize surfaces with amine groups. Although the discharge produced from air is highly oxidative and the gas temperature is high as compared to other atmospheric plasma sources, amine groups, as well as amide ones, were identified in the nanometers thick coatings by XPS and FTIR analysis. By comparing the results with post-treatment and -grafting experiments, the partial retention of amine groups might be explained by the non-ideal mixing of the precursor flow with the main gas stream inside the plasma jet. Beside the intrinsic plasma reactivity, hydrodynamics effects are indeed important when considering flowing atmospheric plasmas.

// Sudhir Bhatt 1, 3 , Fatemeh Valamanesh 2 , Jerome Pulpytel 1 , Rea Lo Dico 2 , Aliby Baiyukha 1 , Iman Al-dybiat 2 , Marc Pocard 2 , Farzaneh Arefi-Khonsari 1 , Massoud Mirshahi 2 1 Sorbonne Universites, UPMC Univ. Paris 6, CNRS, Laboratoire Interfaces et Systemes Electrochimiques, 75005, Paris, France 2 Sorbonne Paris Cite Universites, UMR Univ. Paris 7, INSERM U965 Carcinose, Angiogenese et Recherche Translationnelle, L’Hopital Lariboisiere, 75010, Paris, France 3 Current address: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, 23508, VA, USA Correspondence to: Massoud Mirshahi, email: massoud.mirshahi@inserm.fr Keywords: plasma polymers, biodegradable coatings, in vivo drug delivery system, anti-cancer drug, targeted therapy Received: May 11, 2016 Accepted: July 19, 2016 Published: July 29, 2016 ABSTRACT A low pressure plasma process based on plasma deposition has been used to develop a drug delivery strategy. In this study, a drug delivery system based on different layers of plasma co-polymerized Poly e-caprolactone-Polyethylene glycol (PCL-PEG) co-polymers was deposited on biocompatible substrates. Cis-platinum (118 μgm/cm 2 ) was used as an anti-cancer drug and incorporated for local delivery of the chemotherapeutic agent. The co-polymer layers and their interaction with cancer cells were analyzed by scanning electron microscopy. Our study showed that the plasma-PCL-PEG coated cellophane membranes, in which the drug, was included did not modify the flexibility and appearance of the membranes. This system was actively investigated as an alternative method of controlling localized delivery of drug in vivo . The loading of the anti-cancer drug was investigated by UV-VIS spectroscopy and its release from plasma deposited implants against BALB/c mice liver tissues were analyzed through histological examination and apoptosis by TUNEL assay. The histological examination of liver tissues revealed that when the plasma-modified membranes encapsulated the cis-platinum, the Glisson’s capsule and liver parenchyma were damaged. In all cases, inflammatory tissues and fibrosis cells were observed in contact zones between the implant and the liver parenchyma. In conclusion, low pressure plasma deposited uniform nano-layers of the co-polymers can be used for controlled release of the drug in vivo.

STSM grant by COST ACTION MP1101 “Biomedical Applications of Atmospheric Pressure Plasma Technology” is acknowledged. Financial support by Innovaciones DisRas S.L. Company is also acknowledged.

International audience; A pulsed-arc atmospheric pressure air plasma jet has been used to depositplasma polymerized acrylic acid/methylene-bis-acrylamide (ppAA/MBA) organic thinfilms. Optical emission spectroscopy has been performed to investigate the reactivity of theplasma and the dissociation of the precursor as a function of the pulse frequency anddistance from the nozzle. An estimation of the OH rotational temperature, which is anindicator of the plasma gas temperature, has also been performed. By heating the substrateduring deposition, it was possible to improve to a great extent the stability to water of thecoatings. Stable ppAA/MBA films have been obtained with an air plasma over a largerange of pulsed frequencies (from 15 to 25 kHz) when the substrate was heated to 200° C.The composition of these coatings was investigated by FTIR and different amide/acidratios were obtained, showing the possibility to grow stable films with different functionalgroups by adjusting the deposition parameters.

There exists an abundant literature on polymers used for biomedical applications. However, the research described in this article deals with the plasma (co)polymerisation of different organic precursors for surface modifications of a variety of substrates in order to tailor the physico-chemical properties of the substrates for tuneable biomolecule–surface interactions. The major part of the work presented focuses on the low-pressure inductively excited plasma-enhanced chemical vapour deposition of organic precursors for the functionalisations of material. In the second part of the article, an open-air custom-made atmospheric-pressure dielectric barrier discharge (DBD) plasma jet is discussed for the anti-fouling applications. This special focus aims to elaborate the state of the art of different low and atmospheric pressure plasma-deposited polymers for anti-fouling applications, cell–surface interactions and tissue engineering applications.

Enhanced TiO

International audience; For targeting the cancer cells, a low pressure ICP reactor was utilised to fabricate a drug delivery system. On the surface of biocompatible collagen membranes, thin plasma polymer coatings were deposited to encapsulate an anticancer drug carboplatin and impart different biologically active functionalities. The characteristics of the deposited films were analysed by FTIR and XPS and the overall functionalities were tested by in vitro and in vivo experiments on the cancer cells lines on the cancer nodules respectively. Preliminary results of fabricated drug delivery systems showed the inhibition of cancer cell proliferation in vitro as well as tumour growth in mice models by 2.8 folds in mass compared to the control case

International audience; In order to obtain a durable cost-effective membrane for membrane distillation (MD) process, flat sheet polyethersulfone (PES) membranes were modified by an atmospheric pressure nonequilibrium plasma generated using a dielectric barrier discharge in a mixture of argon and hexamethyldisiloxane as the organosilicon precursor. The surface properties of the plasma-modified membranes were characterized by water contact angle (CA), liquid entry pressure, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water CA of the membrane was increased from 64° to 104° by depositing a Si(CH3)-rich thin layer. While the pristine PES membrane was not applicable in the MD process, the modified PES membrane could be applied for the first time in an air gap membrane distillation setup for the removal of benzene as a volatile organic compound from water. The experimental design using central composite design and response surface methodology was applied to study the effects of feed temperature, concentration, and flow rate as well as their binary interactions on the overall permeate flux and separation factor. The separation factor and permeation flux of the modified PES membrane at optimum conditions were comparable with those of commercial polytetrafluoroethylene membrane.

Surface activation of polymers by atmospheric pressure plasma is an economically important process for bonding technologies. Although most of the studies are focused on the modification of the surface chemistry, this study investigates the modification of the topmost surface and the deeper layers of a polyamide-6 sheet treated by an open-air atmospheric plasma jet system. The plasma jet used in this study is a unique combination of highly reactive species (e.g. O8, 8OH. . .) and a high temperature gas estimated (from 600–1 000 K) which leads to surface functionalization,amorphization and polymorphism modification. The results have shown that an amorphization of the polyamide occurs on the top surface. Moreover, a crystallization of the amorphous phase in the a form was also highlighted in the depth of the material.

Water stable plasma polymerized acrylic acid/methylene-bis-acrylamide (ppAA/MBA) thin films have been deposited with an atmospheric pressure air plasma jet, a fast technique to grow organic thin films. To increase the stability of the coatings, a cross-linking agent (MBA) was added to the precursor (AA), which was introduced with a home-made spraying system. The jet speed and pulse frequency of the discharge were investigated regarding the properties of the coatings. Two types of materials were obtained: in low energy conditions (high jet speed and low frequency) the films presented a water-soluble part with a certain organized structure. When more energy is supplied to the growing films, a more polymerized material with a more amorphous structure is obtained. Increasing the energy further leads to the deposition of a more cross-linked film with a better stability to water. In optimized conditions, no weight loss and no significant chemical change were noticed after soaking in water.

N-doped TiO2 thin films have been deposited by reactive RF magnetron sputtering at different total gas pressures and varying O 2/N2 gas flow rates at 300 C. The thin film nanostructure has been studied by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Increasing the deposition pressure leads to reduced crystallinity of the thin films and a higher N2 flow rate was required to incorporate N into the growing film. This is attributed to the lower energy ion bombardment of the surface and N adatom chemical reactivity being reduced at higher total gas pressures. Ar+ ion sputtering of the deposited N-doped TiO2 thin films has enabled a detailed XPS investigation of the surface and bulk N species to be performed. Adsorbed N species have been identified on all the deposited thin film surfaces, with the most prevalent adsorbed N species occurring at a binding energy of approximately 400 eV, shown to originate from atmospheric contamination, most probably N containing organic species. The bulk N content varies between 0.6 and 6.0 at.% and N is located predominantly at substitutional sites in the TiO2. The presence of interstitial N, in the form of NO species, has been identified by XPS in some thin films deposited at higher deposition pressures. Hence, varying the total gas pressure may provide a route for tailoring the location of N in the bulk structure. At higher N contents (> 3 at.%), TiN is found as a secondary phase within the bulk structure and the presence of TiN leads to a sharp reduction in the band gap. Post-deposition annealing of low N containing films results in an N-doped TiO2 single phase anatase structure. © 2013 Elsevier B.V.

A custom made non-equilibrium atmospheric pressure argon plasma jet was developed for the deposition of PEG like coatings in open-air for cell repellent applications. OES and electrical measurements were performed to characterize the discharge. The emission of the N2 (C3Πu–B3Πg) was followed in order to minimize the air entry in the plasma. Surface analyses were carried out on ap-DEG coatings and the best retention of COC was obtained under mild plasma conditions. The ap-DEG coatings were compared with typical LP deposited PEG like coatings. Less retention of COC and therefore less cell repellent properties were observed for ap-DEG coatings as compared to those deposited at low pressure.

In this work, a simple and rapid method was used to functionalize carbon electrode in order to efficiently immobilize laccase for biosensor application. A stable allylamine coating was deposited using a low pressure inductively excited RF tubular plasma reactor under mild plasma conditions (low plasma power (10 W), few minutes) to generate high density amine groups (N/C ratio up to 0.18) on rough carbon surface electrodes. The longer was the allylamine plasma deposition time; the better was the surface coverage. Laccase from Trametes versicolor was physisorbed and covalently bound to these allylamine modified carbon surfaces. The laccase activities and current outputs measured in the presence of 2,2'-azinobis-(3-ethylbenzothiazole-6-sulfonic acid) (ABTS) showed that the best efficiency was obtained for electrode plasma coated during 30 min. They showed also that for all the tested electrodes, the activities and current outputs of the covalently immobilized laccases were twice higher than the physically adsorbed ones. The sensitivity of these biocompatible bioelectrodes was evaluated by measuring their catalytic efficiency for oxygen reduction in the presence of ABTS as non-phenolic redox substrate and 2,6-dimethoxyphenol (DMP) as phenolic one. Sensitivities of around 4.8 μA mg(-1)L and 2.7 μA mg(-1)L were attained for ABTS and DMP respectively. An excellent stability of this laccase biosensor was observed for over 6 months.

Catalyst and solvent free low pressure RF plasma polymerization strategy was used to develop multilayer biodegradable PCL-co-PEG (poly (e-caprolactone)-poly (ethylene glycole) copolymer) coatings for the controlled delivery of anticancer drug to reduce the nephrotoxicity (toxic effects to kidney cells) and myelosuppression (decrease in red blood cells). The resulting PCL-co-PEG coatings were characterized by FTIR-ATR and XPS. Multilayer drug delivery device can be tailored in such a way to have controlled cell–surface interactions and barrier layer dependent release. Cisplatin loaded (118 μgm/cm 2 ) PCL-co-PEG coatings with optimized ratios of e-CL/DEGME monomer feed in the plasma reactor were prepared for controlled cell death applications. Methylene blue (MB) was used as a model for cisplatin to simulate the drug release kinetics and the nature of which was examined by using the Korsmeyer–Peppas model for polymer coatings. Barrier layer dependent release was investigated by varying the deposition time from 5 to 50 min. Ellipsometric measurements were performed to understand the influence of surface hydration over the different chemically functionalized coatings with the incubation time. Human ovarian carcinoma cells (NIH:OVCAR-3) were cultured in physiological conditions and were seeded in a microplate which was loaded with autoclave coated glass cover slips for different time durations. Cell viability assay was performed to analyze the cell death. The results show that by gradually increasing the barrier layer thickness with deposition time, the amount of MB release was decreased which was modeled by analyzing the MB release kinetics. Investigations of each layer for multilayer PCL-co-PEG coatings were demonstrated over the drug delivery applications in vitro .

For the first time, a fast and versatile technique, an atmospheric pressure plasma jet (APPJ), has been used to functionalise graphite carbon electrodes for biofuel cell applications. The bioelectrode was functionalized by an atmospheric pressure plasma jet (APPJ) system using air, oxygen (O2) and nitrogen (N2) plasmas applied for only a few seconds. XPS analysis showed that carboxylic groups were created on the carbon substrates using both air and O2 plasmas, while mainly carbonyl and amine/amide functionalities were generated using N2 plasmas. A purified laccase from Trametes versicolor was both adsorbed and covalently bound (NHS/EDC method) to the plasma modified carbon. Higher laccase activity was obtained for the covalently grafted laccase compared to the physically adsorbed one: 13.2 (± 2) 10− 3U of laccase on air treated graphite and two-fold less (5.3 (± 1.1) 10− 3U) were obtained on N2 plasma treated surfaces (1 mM ABTS as a substrate, 30 °C, pH = 3.0), one unit (U) being the quantity of ABTS (μmole) oxidized by laccase per minute. Dioxygen reduction was performed by direct electron transfer (DET). The highest current density, 108 μA/cm2 (at 0.2 V (vs. SCE), pH 4.2, room temperature), was recorded for covalently immobilized laccase on N2 plasma treated surfaces (geometric surface = 0.38 cm2). This could be explained by the fact that the highly conductive graphite structure was retained in the case of this surface treatment and could also suggest a preferential orientation of the T1 Cu center of the laccase toward the surface of the N2 plasma treated electrode.

Plasma polymerized polyacrylic acid (PPAA) was deposited on a polymer substrate, namely polyethylene terephthalate (PET) mesh, for entrapment of silver nanoparticle (Ag-NP) in order to achieve antibacterial property to the material. Carboxylic groups of PPAA act as anchor as well as capping and stabilizing agents for Ag-NPs synthesized by chemical reduction method using NaBH4 as a reducing agent. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle analysis were used to characterize the PPAA coatings. The Ag-NPs loaded polymer samples were characterized by UV–visible spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray, and XPS techniques. XPS analysis showed ∼1.0 at.% loading of Ag-NPs on to the PPAA-PET-mesh, which was composed of 79% zero-valent (Ag°) and 21% oxidized nano-Ag (Ag+). The plasma processed PET meshes samples were tested for antibacterial activity against two bacterial strains, namely Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Qualitative and quantitative tests showed that silver containing PPAA-PET meshes exhibit excellent antibacterial property against the tested bacteria with percent reduction of bacterial concentration >99%, compared to the untreated PET mesh. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

Polyacrylic acid thin films have been deposited by an original and fast technique to grow organic coatings: a pulsed-arc atmospheric pressure plasma jet. Liquid acrylic acid was introduced in the nitrogen plasma jet and OES was used to measure the fragmentation of the precursor. The films were characterized by XPS, FTIR and SEM analyses before and after soaking in water. The water stability was also investigated by weight loss measurement. A high retention of carboxylic moieties, i.e. functional groups of the monomer has been observed for coatings deposited under mild conditions for the jet (low frequency and high jet speed). These films have been used for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR-3). Good results have been obtained depending on the plasma parameters, showing that atmospheric pressure plasma jet is a promising technique to grow organic thin films for biomedical applications.

Catalyst-free ring-opening polymerization (ROP) strategy was developed to overcome the disadvantage of incomplete and expensive removal of catalyst used during the multistep wet chemical processes. Nano-sized biocompatible and low molecular weight poly(ε-carolactone)-poly(ethylene glycol) (PCL-PEG) copolymer coatings were deposited via a single-step, low-pressure, pulsed-plasma polymerization process. Experiments were performed at different monomer feed ratio and effective plasma power. The coatings were analyzed by XPS, as well as MALDI ToF. Ellipsometric measurement showed deposition rates ranging from 1.3 to 3 nm/min, depending on the ratio of the PCL/PEG precursors introduced in the reactor. Our results have demonstrated that plasma copolymerized PCL-PEG coatings can be tailored in such a way to be cell adherent, convenient for biomedical implants such as artificial skin substrates, or cell repellent, which can be used as antibiofouling surfaces for urethral catheters, cardiac stents, and so on. The global objective of this study is to tailor the surface properties of PCL by copolymerizing it with PEG in the pulsed plasma environment to improve their applicability in tissue engineering and biomedical science.

The ammonia plasma process was used for generating reactive groups, particularly primary amine functions on the surface of polyethylene (PE) films, to immobilize the enzyme trypsin. The attachment of the enzyme was achieved by directly applying an aqueous solution of trypsin to the plasma-activated surface or by using glutaraldehyde as a chemical linker. In both cases, the utilization of sodium cyanoborohydride efficiently stabilized the immobilization. The surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and enzymatic activity measurements. Active trypsin was successfully immobilized on the surface with a mean activity of 0.09 ± 0.02 U/cm(2). The study of the stability of the immobilized enzyme during repetitive assays showed that some activity could be maintained during several months. An original quantitative correlation between the immobilized enzyme activity and the XPS signal intensity of the S 2p electrons present in the sulfur-containing amino acid residues was evidenced.

Silicon oxide based (SiOxCyHz, noted SiOx) coatings are often used in surface engineering for microelectronics, corrosion resistance, barrier to gas permeation through polymeric materials, etc… SiOx coatings can be efficiently deposited by non-equilibrium atmospheric pressure plasma processes, such as DBD or plasma jets. In the present study, the design of experiment (DoE) methodology was used to investigate the influence of process parameters on the characteristics of organosilicon coatings deposited by a non-equilibrium atmospheric pressure plasma jet (APPJ) from hexamethyldisiloxane (HMDSO) and air mixtures. The results obtained were used to create an empirical model to predict the chemical composition of coatings. Among 11 process parameters, the 3 parameters which exhibited the strongest effect on the coating composition were the torch speed, the substrate to nozzle distance and the number of scans. Auger spectroscopy revealed that the carbon content of the thin films was as low as 6 ± 1.7% and AFM analysis showed that smooth coatings (Ra ∼ 2 nm) were obtained even at high dynamic growth rates (∼1 000 nm · m · min−1). A tentative macroscopic scaling law was also formulated to correlate our results with the available literature data.

The present study deals with the deposition of plasma polymerized acrylic acid (PPAA) coatings on the surface of polystyrene beads. XPS analysis showed that the COOH content of the unwashed surface decreased by increasing the power, whereas the resistance to washing was improved weakly. The results showed that the use of an argon pretreatment of PS beads before plasma deposition of AA leads to a strong adhesion between PPAA coating and the underlying PS, reinforcing its stability. The study of the influence of the plasma deposition time clearly showed that the COOH content increased with the plasma treatment time, due to a better coverage of the PS beads. However, the stability of such coatings decreased inversely with the plasma treatment time due to their delamination.

Environmentally benign-solvent free plasma process is employed to produce nanostructured PFDA-co-DEGDME amphiphilic coatings via plasma co-polymerisation of 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) and diethyleneglycol dimethyl ether (DEGDME) precursors in a low pressure-RF-inductively excited tubular plasma reactor using argon as a carrier gas. The plasma-polymerised coatings are characterised by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle measurements. PFDA-co-DEGDME coatings with varying chemical environments and morphologies are achieved by varying the plasma parameters such as, continuous wave (CW) and pulse modulated (PM) plasma mode, and plasma deposition time. Plasma polymerised PFDA-co-DEGDME coatings are found to exhibit a switching property in terms of wettability, i.e., from hydrophobic to hydrophilic and vice versa, in response to the contacting environment. Quartz crystal microbalance (QCM) is used to study the adhesion of two model proteins, namely, human serum albumin (HSA) and fibrinogen (FGN) in continuous flow conditions, which reveals the protein repellent, i.e., anti-biofouling characteristics of the PFDA-co-DEGDME amphiphilic coatings.

Low surface energy fluorocarbon polymer coatings were prepared via plasma enhanced chemical vapor deposition (PECVD) of 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) in a low pressure inductively excited RF plasma. The influence of plasma parameters, such as, deposition time, continuous wave (CW) and pulse modulated (PM) plasma mode, plasma power and plasma duty cycle (DC) on morphology and wettablity of the PFDA was investigated using field emission scanning electron microscopy (FESEM) and contact angle (CA) measurement techniques. The plasma mode, plasma power and pulse duty cycle played a pivotal role in tailoring the surface morphology, wettability and the surface energy of the PFDA coating. The water CA hysteresis values for PFDA coatings suggested the wetting characteristics of the coating satisfying Wenzel model of nanostructured solid-water wetted contact. A thin conformal PFDA coating transformed a super-hydrophilic Whatman filter paper into a super-hydrophobic and oleophobic surface, which has industrial applications for development of durable, stain resistance and liquid repellent papers. The antifouling property of PFDA coatings investigated by quartz crystal microbalance (QCM) exhibited the protein repellent behavior against three model proteins namely, ovalbumin (OVA), human serum albumin (HSA) and fibrinogen (FGN).

International audience; Polypropylene (PP) particles are used for various purposes, however, the good mechanical properties of PP are counterbalanced by a poor wettability. The wettability of PP particles was therefore improved by an atmospheric pressure blown‐arc air plasma jet treatment in a new designed homemade Wurster fluidized bed reactor (Wurster‐FBR). This reactor, was used to treat 200 g of particles per batch. The surface free energy of PP particles determined by the Zisman method showed an increase from 30.7 to 38.6 mN m−1 after 120 s of treatment. XPS results showed a 5% increase of the atomic concentration of oxygen on the surface of the treated particles. In order to describe the process, a 2D axisymmetric non‐isothermal k‐ϵ turbulent model was used to determine the velocity field, pressure, and temperature profile of the gas phase inside the reactor. Furthermore an Eulerian‐Eulerian multiphasic CFD model was added to determine the dynamics of the particles inside the reactor, and the results were compared with fast imaging, thermocouple, and anemometry measurements. These investigations are very important to monitor the homogeneity of the particle treatments, to determine the average effective treatment time for each particle and to avoid overheating of thermally sensitive PP.

International audience; A novel hydrophobic membrane was developed by means of plasma polymerization of the polyethersulfone (PES) membrane using ethylene as the precursor to obtain appropriate performance in the membrane distillation (MD). The effects of plasma treating parameters including duration time, gas pressure, and power on the surface properties of the treated membranes as well as their MD performances were discussed. The surface properties of the treated samples were evaluated in terms of the surface morphology, chemistry, porosity and pore size, roughness, hydrophobicity, and Liquid Entry Pressure (LEP). The treated hydrophobic PES membranes with water contact angles of as high as 115° were obtained at high pressures and moderate powers. Response surface methodology was applied for modeling and optimization of the Air Gap Membrane Distillation (AGMD) system to separate benzene as a volatile organic compound from water. The plasma treated membranes showed fluxes at least as high as those of the commercial polytetrafluoroethylene (PTFE) membranes.

The thin film deposition in DBDs fed with Ar/HMDSO/O2 mixtures was studied by comparing the FT-IR spectra of the deposits with the GC-MS analyses of the exhaust gas. Under the experimental conditions investigated, oxygen addition does not enhance the activation of the monomer while it highly influences the chemical composition and structure of the deposited coating as well as the quali-quantitative distribution of by-products in the exhaust. Without oxygen addition a coating with high monomer structure retention is obtained and the exhaust contains several by-products such as silanes, silanols, and linear and cyclic siloxanes. The dimethylsiloxane unit seems to be the most important building block of oligomers. Oxygen addition to the feed is responsible for an intense reduction of the organic character of the coating as well as for a steep decrease, below the quantification limit, of the concentration of all by-products except silanols. Some evidences induce to claim that the silanol groups contained in the deposits are formed through heterogeneous (plasma-surface) reactions.

We present a process for rapid post-discharge deposition of liquid monomer to form functional coatings at atmospheric pressure. The post-discharge polymerization of dense polyacid and polyether coatings is first depicted versus the energy density deposited by the preliminary surface treatment of polyethylene and polystyrene substrates in air Dielectric Barrier Discharge (DBD) with respect to SEM, to XPS and FTIR-ATR analysis and to polymerization yield determined by mass measurements. The paper focuses on the effect of the filamentary air DBD on surface of the polymer substrates and on post-discharge polymerization mechanism. Indeed, the grafting yield is shown to depend on the energy density deposited by DBD and on the time exposure to air between DBD and monomer deposition, controlling respectively the surface density of radicals and labile peroxides, both triggering the polymerization of vinyl precursors. Then, the effect of deposition conditions on the polymerization yield and related thickness of the functional polymer coatings is shown and special attention is paid to the stability of the coating upon washing.

Plasma processing has been developed to produce selective chemistry in the inner surface of a microfluidic system. This dry process is an alternative solution to the Chemical Vapor Deposition (CVD) process that allows us to work at low temperatures thus avoiding the degradation of the substrate by heat. The present study focused on the surface modification of PDMS in order to make them more hydrophilic and capable to exhibit a high percentage of COOH functions which will provide a good asset for future cell attachment.

Coronary stents are metallic (316L stainless steel) devices employed during balloon angioplasty to reopen and prevent the re-obstruction of a diseased narrowed area within a coronary artery. To reduce restenosis rate, bare metal stent coating is a promising solution. The coating can act as an anticorrosive barrier against the aggressive properties of biological environment, improving the long-term safety of the device. The goal of this study is to develop a dry process to isolate metallic surface from the biological environment by depositing a thin plasma polymerized allylamine (CH2=CH-CH2-NH2) film on the metallic surface. Plasma polymerized allylamine films were deposited on flat electropolished 316L stainless steel samples in a low pressure plasma reactor (70 kHz). Chemical composition of the coatings has been analysed as a function of the discharge power and treatment time. Moreover, special attention has been paid on the stability of the coating after immersion during 24 hours in D.I. water. Finally, to mimic stent expansion conditions, a “small punch test” has been used to investigate the adhesive properties of the coating. Our results demonstrate that is possible to deposit a stable, cohesive and adhesive plasma polymerized allylamine thin film which can be used as a coating for cardiovascular stents

article i nfo This paper presents the manufacturing of biochips by using the COOH- derived polymer coating deposited by plasma polymerization of acrylic acid. This technology is based on depositing a thin layer obtained by plasma polymerization of acrylic acid which allows a further covalent immobilization of biomolecules on glass substrates. The plasma power value was optimized to maximize the stability of plasma polymerized acrylic acid (PPAA) coatings in water, which has a very important role for such applications. In order to obtain a covalent immobilization of DNA probes on the PPAA coated surface, the activation protocol of carboxylic function was carried out with the help of N-Hydroxy Succinimide and 1-Ethyl-3-(3-DimethylAminopropyl) Carbodiimide. The efficiency of PPAA coated in microarray applications was compared with two types of commercial slides. Such surfaces have shown very interesting results in terms of relative density of attached DNA probe molecules and signal-to-background ratio measured for target DNA hybridization. Nonspecific DNA bonding measurements showed only a small amount of nonspecific physisorption between the DNA probe and the PPAA-activated surfaces. This work shows that the plasma polymerization technique can be successfully applied to produce a high-quality glass surface for the manufacturing of DNA arrays.

The aim of this work was to test and to compare different methods reported in the literature to quantify amine and aldehyde functions on the surface of polyethylene (PE) films treated by ammonia plasma and to specify their stability against time. A low pressure ammonia plasma reactor was used to functionalize PE films with amine groups, which could be subsequently used for further immobilization of biomolecules. In order to determine the density of amine groups on the surface of treated films, various molecule probes and spectrophotometric analytical methods have been investigated. Two methods using (i) sulfosuccinimidyl 6-[3'-(2-pyridyldithio)-propionamido] hexanoate (sulfo-LC-SPDP) and (ii) 2-iminothiolane (ITL) associated with bicinchoninic acid (BCA) have been proved to be reliable and sensitive enough to estimate the surface concentration of primary amine functions. The amount of primary amino groups on the functionalized polyethylene films was found to be between 1.2 and 1.4 molecules/nm2. In a second step, the surface concentration of glutaraldehyde (GA), which is currently used as a spacer arm before immobilization of biomolecules, has been assessed: two methods were used to determine the surface density of available aldehyde functions, after the reaction of GA with the aminated polyethylene film. The concentration of GA was found to be in the same range as primary amine concentration. The influence of aging time on the density of available amino and aldehyde groups on the surfaces were evaluated under different storage conditions. The results showed that 50% of the initial density of primary amine functions remained available after storage during 6 days of the PE samples in PBS (pH 7.6) at 4 degrees C. In the case of aldehyde groups, the same percentage of the initial density (50%) remained active after storage in air at RT over a longer period, i.e., 15 days.

Hexamethyldisiloxane was used to deposit silicon dioxide thin films using a low frequency plasma reactor at low pressure as well as a dielectric barrier discharge (DBD) at atmospheric pressure. FT-IR, XPS, EIS, SEM and ellipsometry were used to analyse the samples. The results show that, at low pressure, the deposited films which are smooth, continuous and dense present a polymer-like structure. By carrying out the film deposition after an oxygen plasma pretreatment step, a further improvement in the protective properties is achieved, which is observed in the case of SiOχ coatings with 13.56 MHz RF generators.1 At atmospheric pressure, the deposited films present an inorganic character deposited in open air and a polymer-like one deposited under a controlled nitrogen atmosphere in our DBD reactor. The latter also allows continuous films which present the best anti-corrosive properties (which have been studied for the first time for anti-corrosive properties) when they contain some carbon incorporated.

Plasma polymerized acrylic acid (PPAA) coatings were deposited on PE films, in a 70 kHz low pressure plasma reactor, at various plasma powers. The COOH retention of PPAA coatings and its stability to washing in water were investigated by XPS, WCA (water contact angle), FTIR, ellipsometry and SEM analyses. The results have shown that the use of higher powers leads to an increase of the stability of the coating due to a high degree of cross-linking. Under optimized conditions, it is possible to obtain stable PPAA coatings which resist to washing with a COOH retention rate of 15% on PE, which is much higher than the coating deposited in a 13.56 MHz discharge. This high stability of the coatings observed in the low frequency discharge, which is somewhat similar to DC glow discharges, is probably due to the ions which play an important role in the cross linking process of the coatings. Optical emission spectroscopy measurements (OES) have shown good correlation between the CO density in the gas phase and the carboxylic content of PPAA coating.

Deposition of poly(acrylic acid) films has been carried out in air by electrohydrodynamic atomization in post dielectric barrier discharge at atmospheric pressure. The topmost surface layer of the coatings has been analyzed by X-ray photoelectron spectroscopy, revealing a high level of retention of the carboxylic acid functionality, up to 80%. These films are found to exhibit a low water contact angle and a high resistance to washing.

In this paper plasma processing of polymer films and particles is examined by coating and noncoating plasmas. OTS-SAM (octadecyltrichlorosilan self-assembled monolayers) grafted to silicon wafers were used as a model to mimic the structure of PE. The authors believe that the difference by a factor of three in the etching rate between SAM and PE films in ammonia plasma is the consequence of their quasi-crystalline arrangement, compared to the amorphous PE films. For the surface treatment of polymer particles a fluidized bed low pressure plasma has been used. With the help of LDA (Laser Doppler Anemometry) measurements the real time during which the particles were exposed to the plasma was determined. A coating plasma such as allylamine was used to obtain tailored material presenting amino groups on particles. The development of the quantitative chemical derivatization assisted by UV–Visible measurements showed that it was possible to incorporate up to a maximum of 110 nmol of amino groups per gram of powders under specific conditions. Moreover, by using appropriate blocking agents, this derivatization technique allows to differentiate between primary, secondary and tertiary amino groups.

A line-shaped atmospheric pressure filamentary plasma is developed to carry out the open air deposition of silicon oxide films from N 2 /hexamethyldisoxane (HMDSO) mixtures with/without adding oxygen. FT-IR, XPS, SEM, and ellipsometry were used to analyse the samples. It is found that the deposited films present mainly inorganic characteristics even without an oxygen admixture in the open air system. Smooth, continuous, and uniform films can be formed at relatively low monomer content. By increasing the monomer content for a fixed power density or oxygen in the input gases, the deposition rates increase and then show a plateau, suggesting that there exists saturation values for the deposition rates corresponding to the monomer and oxygen content. By the comparison of films deposited in the open air device and in a controlled nitrogen atmosphere in the same device, the important role of the oxygen in the open air reactor has been shown. This study exhibits a potential of open air deposition at atmospheric pressure to form SiO 2 films for large-scale deposition.

Threshold ionization mass spectrometry (TIMS) has been used to measure the excited molecular oxygen states O2 (1Δg) and during plasma-assisted chemical vapour deposition of tin oxide (SnO2) thin films. The latter, composed of nanosized features, was deposited by feeding in a mixture of Ar, O2 and tetramethyltin (Sn(CH3)4 or TMT) in a capacitively coupled RF discharge reactor. Langmuir probe measurements were performed along with TIMS to measure the electron temperature and density. The correlations between these two diagnostic methods have been investigated. The observed densities of O2 (1Δg) and in the γ mode of the discharge are maximum at a low electron temperature and high density. Furthermore, these results have been shown to be correlated to the trend of the electronic conductivity of the deposited SnO2 thin films.

Chemical functionalities, topography and adherence between Al and polyethylene terephthalate (PET) films, modified by laser treatment below the polymer ablation threshold fluence in air and in helium at different wavelengths, fluences, pulse numbers and by low pressure plasma treatment in He 95% with O2 5%, at 0.2 W/cm3 were investigated by XPS, AFM, water contact angle and adhesion measurements. XPS results revealed (i) formation of polar-oxygenated functional groups (C O, O C O) by laser treatments in air and (ii) incorporation of ester and ether groups by plasma treatment in He 95% with O2 5%. After deposition of thermally evaporated Al on laser or plasma treated PET films, U-Peel tests indicated that laser treatment in air at 248 nm and 20 mJ/cm2, and plasma treatment improved Al/PET adhesion. XPS studies revealed the presence of an increasing number of Al O C stable and cohesive interfacial complexes formed by chemical interaction between aluminium and the laser treated in air or plasma treated in He 95% with O2 5% PET films. These interfacial compounds play an important role in the enhancement of the metal/polymer adhesion.

Summary: Thin films of plasma-polymerized allylamine (PPAA) have been deposited onto polyethylene powders (PE) and polystyrene (PS) beads by using a low-pressure 13.56 MHz plasma in a fluidized bed reactor. Chemical derivatization using a set of three different blocking agents has allowed quantitative measurement of the relative percentages of primary, secondary, and tertiary amines. Under optimized conditions, it is possible to incorporate up to 110 nmol of amine groups per gram of powder and with a selectivity of 75% for primary amines. Moreover, our data clearly show that for films deposited at 10 W the selectivity for primary amines is at a maximum, but this is at the expense of resistance to washing. A power of 20 W corresponds to an optimum value since both the amount of primary amines and the degree of resistance of the coating to solvents reach maximum values. Distribution of the primary (I), secondary (II), and tertiary (III) amine groups on plasma-polymerized allylamine films deposited on polyethylene powders.

A combination of a fluidized bed and a low pressure plasma has been employed for the surface modification of low density polyethylene (LDPE) powders. Optical Emission Spectroscopy and Laser Doppler Anemometry has been used for the characterization of the reactor. XPS and contact angle measurements were carried out to reveal surface modification of nitrogen and ammonia plasma treatment of LDPE powders. Both nitrogen and ammonia plasma treatment show an increase of the hydrophilic character of the surface treated LDPE powders. XPS analysis shows the incorporation of new functional moieties including C–N, C–O groups on the surface of treated powders. In this configuration nitrogen plasma treatment leads to a better incorporation of nitrogen containing functional groups when compared to ammonia plasma.

We report a simultaneous formation process of textured surfaces for hydrogen-free amorphous carbon (a-C) induced by an ion beam. By adjusting surface reactions via controlling temperature together with ion beams, several kinds of textured surfaces of a-C on mirror-polished Si (111) can be produced during ion-beam assisted deposition. In high-temperature regimes, submicron-sized pyramidlike a-C particles and ripples structures form. The sizes and separations of a-C particles change with substrate temperature significantly. An intrinsic model based on a natural self-organization mechanism is proposed for the production of textured surfaces, where the surface diffusion is shown to play a decisive role. In a low-temperature regime, the films commonly present mounding roughening. Likewise, self-organized nanodots appear at a very low ion flux. These nanodots are about 5±0.5 nm high with a diameter to height ratio close to 15:1 and a density of approximately 290 μm−2. The nanodot production is correlated with i...

We report the self-organized nanostructures of hydrogen-free amorphous carbon (a-C) with controllable characteristic length scales obtained by using ion beam assisted deposition. By selecting various temperature regimes, two kinds of nanostructure, mounds and ripples, are successfully formed. For the growth temperature of 200 °C, the fractal analysis of the surface shows that the lateral characteristic length for mounding structures increases with increasing ion energy. But for ripple structures formed in the relatively high temperature region, the ripple wavelengths are found to show a nonlinear dependence on the ion energy. Further, at certain temperatures there exist energy thresholds for stopping the formation of ripple structures. These results demonstrate that the characteristic scales of nanostructures for a-C can be significantly controlled through the tuning ion energy in a well-defined manner.

In this work an attempt has been made to dope the films by a one step process by introducing a fluorine precursor which was SF 6 with the plasma mixture used for the deposition of tin oxide films. Optical emission spectroscopy and mass spectrometry were used to study the plasma phase and the characterization of the films was carried out by different diagnostic techniques such as SEM, XPS and FTIR. An increase of the electrical conductivity was obtained for very small flow rates of SF 6 introduced in the discharge (from 95 to 130 S cm −1 ). For higher flow rates, a sharp decrease of the conductivity was observed. For such flow rates, competitive etching and functionalization processes, assisted by fluorine atoms present in the discharge, take place. Although the conductivity dropped down, the optical transmission of the deposited films remained higher than 90%.

The modifications induced on poly (ethylene terephthalate) (PET) by an excimer laser radiation or a low pressure plasma as well as their ability to improve Al–PET adhesion were investigated. For this purpose, surface roughness, chemical composition, surface wettability, and adhesion properties of PET were studied depending on the process parameters. Both treatments can significantly enhance the adhesion but the surface change responsible for the improvement was different for each pretreatment.

A global plasma model is used to investigate the chemistry and energy deposition in 13.56 MHz radio-frequency capacitively coupled oxygen–argon discharges under conditions usually used for the deposition of tin oxide films. These models are based on the solution of a stationary electron Boltzmann equation coupled to species balance equations including the vibrational kinetics equations of O2. The results obtained showed that vibrational non equilibrium of O2-molecule is not significant. The dissociation degree of O2 was found to be around a few percents and the discharge was often moderately electronegative even for small O2 contents in the feed gas. The ionization and energy dissipation mechanisms are mainly governed by the collisional processes involving O2 for an oxygen feed gas composition greater than 20%. Results also showed that the predicted densities of the charged species and the electronegative character of the discharge are strongly linked to the assumption made on the homogeneity of the power deposition. On the contrary, the predicted density of O-atom is not sensitive to this assumption.

The modifications induced on PET, poly(ethylene terephthalate), by an excimer laser irradiation performed below the polymer ablation threshold were studied. The laser treatment of the polymer before aluminum thermal evaporation improved the Al-PET adhesion. The enhancement of the metal-polymer interface strength is attributed to surface morphological changes rather than to chemical modifications of the PET surface. Surface oxidation under UV irradiation was found to degrade the adhesion.