[Show abstract][Hide abstract] ABSTRACT: In this work, poly(ethylene terephthalate) (PET) films were treated by oxygen and helium plasmas and their chemistry and morphology were studied. Samples were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water contact angle (WCA) measurements. The aging of plasma-treated PET films was studied in different media (air and water) by WCA. The anti-fouling properties of the plasma treated surfaces were evaluated by confocal microscopy. Both oxygen and helium plasma-treatments produced hydrophilic and nano-structured surfaces that presented a remarkable reduction of the bioadhesive character. Besides, the grafting of plasma treated surfaces was explored using Pluronic F108 in order to improve the anti-fouling properties of the plasma treated surfaces.
[Show abstract][Hide abstract] ABSTRACT: Immobilization of antibody molecules onto hydrophobic polymeric surfaces with disordered orientation is something unwanted in many applications. To overcome this drawback, controlled immunoglobulin G (IgG) immobilization onto poly(vinylidene fluoride) surface was investigated in this paper. A two-step process involving radiofrequency plasma pretreatment for polymer surface functionalization, followed by coupling reaction was developed, after which immunoglobulin G was immobilized onto the surface directly or via protein-A. IR and XPS data proved that the process is more efficient when the radiofrequency plasma pretreatment was performed using N2 and N2/H2 as discharge gases. NIR-CI, AFM and XPS surface evaluation revealed that immobilization of IgG onto N2/H2 plasma-treated PVDF via grafted protein-A was achieved with an ends-on orientation, leaving available the antigen binding sites of IgG. This procedure could be a promising route for the preparation of oriented IgG assembly onto PVDF, useful in biomedical, membranes or sensors applications. QCM results showed a better antibody–antigen interaction when IgG immobilization onto PVDF substrate is mediated by protein A.
Colloids and Surfaces B: Biointerfaces. 03/2014; 115:139-149.
[Show abstract][Hide abstract] ABSTRACT: Polypropylene fiber meshes were plasma-treated in order to attach new chemical functions corresponding to acidic or basic groups without altering the roughness of such thin material. An almost complete wettability of these plasma-treated materials is obtained. Because of the plasma-grafting of acid or amino moieties, such surface treatment allows increasing the adsorption rate of quaternary ammonium molecule like Aliquat 336. This increase was explained by specific interactions of ammonium head of the Aliquat 336 and hydrophilic group of plasma-treated PP, followed by the adsorption of a further layer of Aliquat 336 through hydrophobic interactions of its hydrocarbon chain. These interactions between the carrier and the polymeric surface were characterized leading to physisorption mechanism. Such new material could be applied to the extraction process since no evidence of aging was given.
[Show abstract][Hide abstract] ABSTRACT: The biocontamination is one of the major problems in various industrial sectors, specifically in medicine and environment fields. It has been shown that surface characteristics of materials, such as superhydrophobic character, can allow obtaining " antibioadhesive " surfaces. Indeed, the wetting is reduced which may favor the "sliding" of the aqueous medium on the surface. Hence, its ability to interact with bacteria may also be reduced. This phenomenon is associated with the chemical functionality of the coating and its nano-roughness, in order to not mechanically trap the bacteria. Here, such anti-bioadhesive surfaces are designed from polyethylene terephtalate (PET) by three steps plasma-treatment. First, the nano-roughness is created by oxygen plasma-treatment with controlled dimensions. Then, the plasma-treated polymeric surface was hydrophobized with a tetrafluorocarbon plasma, allowing to obtain a water contact angle of 145 ± 4 °. However, the SEM pictures give evidence of show the degradation of the structuration caused by the CF4-plasma and consequently, the superhydrophobicity was not reached. Thus, a plasma-polypyrrole layer was deposited before the plasma-fluorination, which has a protective role against the degradation generated by fluorinated species, preserving the structuration and improving the fluorination rate. Therefore, the obtained surfaces are superhydrophobic with water contact angle of 157 ± 2 ° and a hysteresis of 65 ± 3 °. The ability of these surfaces to reduce bioadhesion will be performed in further work.
[Show abstract][Hide abstract] ABSTRACT: The aim of this work is to decrease the adhesion between a cured modified epoxy-based substrate and an in situ cured virgin epoxy-based piece. The effect of perfluorinated additives on the non-adhesion output is investigated through an adapted pull-off test. It appears that additive migration initiates the surface fluorination. Longer the fluorinated chain is, higher the surface fluorination is and weaker the adhesion strength is. The weak chemical affinity between these two epoxy resins is shown to be mainly responsible for these results leading to an adhesive rupture.
Composites Part B Engineering 01/2014; 63:94–100. · 2.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Immobilization of antibody molecules onto hydrophobic polymeric surfaces with disordered orientation is something unwanted in many applications. To overcome this drawback, controlled immunoglobulin G (IgG) immobilization onto poly(vinylidene fluoride) surface was investigated in this paper. A two-step process involving radiofrequency plasma pretreatment for polymer surface functionalization, followed by coupling reaction was developed, after which immunoglobulin G was immobilized onto the surface directly or via protein-A. IR and XPS data proved that the process is more efficient when the radiofrequency plasma pretreatment was performed using N2 and N2/H2 as discharge gases. NIR-CI, AFM and XPS surface evaluation revealed that immobilization of IgG onto N2/H2 plasma-treated PVDF via grafted protein-A was achieved with an ends-on orientation, leaving available the antigen binding sites of IgG. This procedure could be a promising route for the preparation of oriented IgG assembly onto PVDF, useful in biomedical, membranes or sensors applications. QCM results showed a better antibody-antigen interaction when IgG immobilization onto PVDF substrate is mediated by protein A.
[Show abstract][Hide abstract] ABSTRACT: Biosourced or biodegradable polymers like poly(lactic acid) (PLA) are often base-material for tissue-engineered scaffolds. However, in most of the cases, their bioadhesion properties are not satisfactory. Since the adhesion is controlled both by roughness and surface chemistry, PLA films were textured by applying the breath figure procedure and, then, plasma-treated. Depending on physicochemical characteristics of the breath figure technique, nice hexagonal structures were obtained. Their surface properties, i.e. hydrophobic-hydrophilic balance were controlled by plasma modification. However, their surface decoration could be only preserved with some specific plasma parameters depending on the applied energy and also on the induced surface chemistry.
[Show abstract][Hide abstract] ABSTRACT: Different polymeric surfaces have been modified in order to reach a high hydrophobic character, indeed the superhydrophobicity property. For this purpose, polypropylene and polystyrene have been treated by RF or μwaves CF4 plasma with different volumes, the results were compared according to the density of injected power. The effect of pretreatment such as mechanical abrasion or plasma activation was also studied. The modified surfaces were shown as hydrophobic, or even superhydrophobic depending of defects density. They were characterized by measurement of wettability and roughness at different scales, i.e. macroscopic, mesoscopic and atomic. It has been shown that a homogeneous surface at the macroscopic scale could be heterogeneous at lower mesoscopic scale. This was associated with the crystallinity of the material. The bioadhesion tests were performed with Gram positive and negative pathogenic strains: Listeria monocytogenes, Pseudomonas aeruginosa and Hafnia alvei. They have demonstrated an antibacterial efficiency of very hydrophobic and amorphous PS treated for all strains tested and a strain-dependent efficiency with modified PP surface being very heterogeneous at the mesoscopic scale. Thus, these biological results pointed out not only the respective role of the surface chemistry and topography in bacterial adhesion, but also the dependence on the peaks and valley distribution at bacteria dimension scale.
[Show abstract][Hide abstract] ABSTRACT: The possibilities for extracting chemical composition-related
information from a singlewavelength X-ray reflectometry experiment are
investigated. It is shown that the X-ray absorption of certain elements
is sufficient to cause a significant effect on the reflectivity curve,
which can be in turn exploited to determine its abundance in the thin
film. The limitations are discussed using simulated data and the
methodology is applied for the determination of the iodine concentration
in iodine-treated thin polyaniline films. More generally the method
appears to be very sensitive for the non-destructive determination of
the weight percentage of metal nanoparticles in thin polymer films.
The European Physical Journal Applied Physics 04/2013; 62(1):10304-. · 0.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Depletion of neuroproteins on the inner walls of storage tubes influences the accuracy of tests used for identification of various neurodegenerative disorders. In this paper, a strategy is described for surface modification of Eppendorf tubes leading to non-adhesive properties towards the recombinant human prion proteins (PrPrec(hum)). Tubes were pre-activated by helium plasma and grafted with three diverse coatings: pure poly(N-isopropylacrylamide) (PNIPAM), PNIPAM admixed with either neutral PEG(20)sorbitan monolaurate (PEG(20)) or positively charged cetyl trimethylammonium bromide (CTAB) at varying plasma activation times and polymer to surfactant ratios. New functionalized surfaces were analyzed by goniometry, streaming potential measurement and X-ray photoelectron spectroscopy, whereas the protein adhesion was monitored by enzyme linked immunosorbent assays and confocal microscopy. The mapping of PrPrec(hum) adhesion associated with surface analyses enabled us to determine that no or negligible depletion of PrPrec(hum) can be obtained by surfaces possessing basic component in the range between 50 and 60 mJ m(-2) and streaming potential ζ(7.4) ~ -50 mV.
[Show abstract][Hide abstract] ABSTRACT: New nonfouling tubes are developed and their influence on the adhesion of neuroproteins is studied. The biomarkers are considered as single components (recombinant prion and Tau proteins) or in a solution of native and pathological forms. The samples are stored for 24 h at 4 °C in virgin and treated tubes layered with two different nanostructured coatings based on poly(N-isopropylacrylamide) with either a positive or a neutral charge, and the protein adhesion is monitored. The recombinant protein with a high pI is repelled from the nanostructured surface that has a negative ζ potential, whereas the recombinant protein with the lower pI is attracted. Furthermore, in the case of complex solutions, neutral nanostructured surfaces are able to retain all amyloid biomarkers.
[Show abstract][Hide abstract] ABSTRACT: The ammonia absorption properties of polyaniline nanostructures are studied in terms of sensitivity, response and recovery times and stability. These characteristics are obtained by measuring, at room temperature, the absorbance variations at 632 nm. The nanostructures are synthesized either by interfacial or rapid or dropwise polymerizations with the oxidant-to-monomer mole ratio equals to 0.5 or 1. The influence of the deposition method (in-situ or drop-coating technique) as well as the nature of the dopant (HCl, CSA or I(2)) on the gas detection properties are also studied. The results show a strong dependence of the morphology on the deposition method, the in-situ technique leads to the best sensitivity and response time. For this deposition method, the nanostructures sensitivity, response time and regeneration rate depend on the synthesis method, the dopant and the mole ratio. The ageing effect after 8 months under ambient conditions and the mechanism of interaction between the polyaniline nanostructures and ammonia molecules are also presented.
[Show abstract][Hide abstract] ABSTRACT: Poly(ethylene-co-vinyl alcohol) (EVOH) films with two different ethylene contents (29 and 44 mol %) have been treated by hydrophobic plasma (CF4, tetramethylsilane (TMS), CF4/H2, and CF4/C2H2). Conditions of the cold plasma treatment were optimized by the water contact angle measurements as a function of the different plasma parameters (plasma power, gas flow, and treatment time). Chemical changes of the film surface were characterized by X-ray photoelectron spectroscopy. The obtained results revealed the presence of fluorine containing functional groups such as CF, CF2, and CF3 in the case of CF4, CF4/H2, and CF4/C2H2 plasma treatment and the presence of SiOxCy compounds after TMS treatment. The morphology of the plasma treated EVOH films was examined by atomic force microscopy, which indicated an increase of the film roughness after treatment. Negligible changes of thermal properties of the modified EVOH films were observed by means of the temperature modulated differential scanning calorimetry. The barrier properties of films were characterized by water permeability measurements. It was found that the hydrophobicity was significantly improved after plasma treatment and for some treated films the water permeability was decreased up to 28%.
The Journal of Physical Chemistry C 04/2012; 116(23):12599. · 4.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: New non-fouling tubes are developed and their influence on the adhesion of neuroproteins is studied. Recombinant prion proteins are considered as a single component representative of hydrophobic proteins. Samples are stored for 24 h at 4 °C in tubes coated with two different coatings: poly(N-isopropylacrylamide) as a hydrophilic surface and a plasma-fluorinated coating as a hydrophobic one. The protein adhesion is monitored by ELISA tests, XPS and confocal microscopy. It appears that the highest recovery of recombinant prion protein in the liquid phase is obtained with the hydrophilic surface while the hydrophobic character of the storage tube induces an important amount of biological loss. However, the recovery is not complete even for tubes coated with poly(N-isopropylacrylamide).
[Show abstract][Hide abstract] ABSTRACT: Cell adhesion is a multi-process phenomenon involving physical, physico-chemical and biological mechanisms. The complexity of interfaces is the reason why progress in the theory of cell adhesion has been slow. Greater understanding of interaction mechanisms has been enhanced by complete knowledge of supports and of biological components, in particular the extracellular matrix, membrane walls, cell multiplication processes and apoptosis. The construction of novel surfaces with strongly hydrophilic or ultrahydrophobic properties has allowed new theoretical advances, while at the same time offering numerous and varied technological applications. These include: • Bioadhesion with mechanical anchoring using ubiquitous surface roughness and deformability of certain micro-organisms. • Physico-chemical bioadhesion or repellence resulting mainly from the energy characteristics of support surfaces. • Processes of sorting and guidance by biomolecules present at the support–biofilm interface, generating biochemical responses that can induce cell multiplication or degeneration (as in cancer), or cell death.
Journal of Adhesion Science and Technology 04/2012; 24(13):2301-2322. · 0.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The main objective of this paper was to illustrate the enhancement of the sensitivity of ELISA titration for neurodegenerative proteins by reducing nonspecific adsorptions that could lead to false positives. This goal was obtained thanks to the association of plasma and wet chemistries applied to the inner surface of the titration well. The polypropylene surface was plasma-activated and then, dip-coated with different amphiphilic molecules. These molecules have more or less long hydrocarbon chains and may be charged. The modified surfaces were characterized in terms of hydrophilic-phobic character, surface chemical groups and topography. Finally, the coated wells were tested during the ELISA titration of the specific antibody capture of the α-synuclein protein. The highest sensitivity is obtained with polar (Θ = 35°), negatively charged and smooth inner surface.
Journal of functional biomaterials. 01/2012; 3(2):298-312.
[Show abstract][Hide abstract] ABSTRACT: This review describes different strategies of surface elaboration for a better control of biomolecule adsorption. After a brief description of the fundamental interactions between surfaces and biomolecules, various routes of surface elaboration are presented dealing with the attachment of functional groups mostly thanks to plasma techniques, with the grafting to and from methods, and with the adsorption of surfactants. The grafting of stimuli-responsive polymers is also pointed out. Then, the discussion is focused on the protein adsorption phenomena showing how their interactions with solid surfaces are complex. The adsorption mechanism is proved to be dependent on the solid surface physicochemical properties as well as on the surface and conformation properties of the proteins. Different behaviors are also reported for complex multiple protein solutions.
[Show abstract][Hide abstract] ABSTRACT: Polyvinylidene fluoride (PVDF) was modified by CO2, N2 or N2/H2 plasmas, which permitted the attachment of short carboxyl or amino groups. A variation of the discharge parameters was performed, for their optimization, as well as for minimizing degradation in favour of acidic, amphiphilic or basic functionalization, respectively. The optimum parameters of discharge for CO2, N2 or N2/H2 plasmas were P = 50 W, gas flow rate Q = 16 × 10−8 m3 s−1, exposure time t = 30–60 s, d = 0.1 m, pressure 15 Pa. The new surfaces were characterized by wettability measurements, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) methods. In a second step, the proteins (triglycine (TG) and protein A) were adsorbed or chemically grafted onto the carboxyl or amino functionalized surface, after EDC/NHS (1-ethyl-3-(-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide) activation of proteins. ATR-FTIR, XPS and AFM investigations confirmed the presence of protein on the surface. The XPS C1s core levels at 286.3 eV (C–N), 288 eV (amide bond) and 298 eV (carboxylic acid), together with variation of the O1s and N1s signals, illustrated the immobilization of proteins. It was established that TG was better attached on surfaces activated with N2/H2 plasma, while protein A was more tightly anchored on CO2, N2 plasma-activated surfaces. The former procedure allowed higher surface densities, while the latter permitted a better chemical control. The results proved that plasma-treated PVDF is a good substrate for protein coating, which can be further used for microorganisms' detection, as evidenced by the immunoassay test.
Journal of Physics D Applied Physics 11/2011; 44(47):475303. · 2.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The surface grafting of multi-polymeric materials can be achieved by grafting as components such as polymers poly(N-isopropylacrylamide) and/or surfactant molecules (hexatrimethylammonium bromide, polyoxyethylene sorbitan monolaurate). The chosen grafting techniques, i.e. plasma activation followed by coating, allow a large spectrum of functional groups that can be inserted on the surface controlling the surface properties like adhesion, wettability and biocompatibility. The grafted polypropylene surfaces were characterized by contact angle analyses, XPS and AFM analyses. The influence of He plasma activation, of the coating parameters such as concentrations of the various reactive agents are discussed in terms of hydrophilic character, chemical composition and morphologic surface heterogeneity. The plasma pre-activation was shown inevitable for a permanent polymeric grafting. PNIPAM was grafted alone or with a mixture of the surfactant molecules. Depending on the individual proportion of each component, the grafted surfaces are shown homogeneous or composed of small domains of one component leading to a nano-structuration of the grafted surface.
Journal of Colloid and Interface Science 10/2011; 362(2):300-10. · 3.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The main objective of this paper was to illustrate the enhancement of the sensitivity of the ELISA titration of Tau proteins while reducing other non-specific adsorptions that could increase the optical densities and could lead to false positives. This goal was obtained thanks to the association of cold plasma and wet chemistries of the inner surface of the titration well. The PP surface was cold plasma-activated, then coated with different amphiphilic molecules bearing either ionic charges and/or long hydrocarbon chains. The support treated and coated with hexatrimethylammonium bromide improves the signal detection of proteins while reducing the background due to non-specific associations of biomolecules such as hyperphosphorylated Tau protein. However, coating with 3-butenylamine hydrochloride could also be suitable.