Polymérisation par plasma à pression atmosphérique : caractérisation des dépôts et leurs applications en biotechnologies

Les plasmas, les polymères plasma et leurs applications biomédicales -- Physico-chimie des plasmas et de la polymérisation par plasma -- Les fonctionnalisations de surfaces polymériques par plasma et procédés analogues -- Application biomédicales des polymères plasma -- Applications biomédicales des PP:N -- Méthodologie expérimentale -- Dépôts de couches minces riches en azote -- Stratégie de caractérisation des matériaux -- Cultures cellulaires -- Dépôt et caractérisation chimique de polymères plasma riches en azote déposés par décharge à barrière diélectrique à pression atmosphérique -- Atmospheric pressure deposition of micropatterned nitrogen-rich plasma-polymer films for tissue engineering -- Chemical characterisation of nitrogen-rich plasma-polymer films deposited in dielectric barrier discharges at atmospheric pressure -- Adhésion de monocytes humaines U937 sur des couches minces organiques riches en azote : Étude des mécanismes d'adhédion cellulaire164

VUV Photodeposition of Thiol-Terminated Films: A Wavelength-Dependent Study

Photoinitiated chemical vapor deposition (PICVD) has become attractive for selective and specific surface functionalization, because it relies on a single energy source, the photons, to carry out (photo-) chemistry. In the present wavelength (λ)-dependent study, thiol (SH)-terminated thin film deposits have been prepared from gas mixtures of acetylene (C2H2) and hydrogen sulfide (H2S) via PICVD using four different vacuum-ultraviolet (VUV) sources, namely, KrL (λpeak = 123.6 nm), XeL (λpeak = 147.0 nm), XeE (λpeak = 172.0 nm), and Hg (λ = 184.9 nm) lamps. Different λ influence the deposition kinetics and film composition, reflecting that photolytic reactions are governed by the gases’ absorption coefficients, k(λ). Thiol concentrations, [SH], up to ∼7.7%, were obtained with the XeL source, the highest reported in the literature so far. Furthermore, all films showed islandlike surface morphology, regardless of λ

Comparison between single monomer versus gas mixture for the deposition of primary amine-rich plasma polymers

peer reviewe

Experimental and theoretical assessment of water sorbent kinetics

ABSTRACT: The kinetics of water adsorption in powder sorbent layers are important to design a scaled-up atmospheric water capture device. Herein, the adsorption kinetics of three sorbents, a chromium (Cr)-based metal–organic framework (Cr-MIL-101), a carbon-based material (nanoporous sponges/NPS), and silica gel, have been tested experimentally, using powder layers ranging from ∼0 to 7.5 mm in thickness, in a custom-made calibrated environmental chamber cycling from 5 to 95% RH at 30 °C. A mass and energy transfer model was applied onto the experimental curves to better understand the contribution of key parameters (maximum water uptake, kinetics of single particles, layer open porosity, and particle size distribution). Open porosity (i.e., the void-to-particle ratio in the sorbent layer) shows the highest influence to improve the kinetics. Converting the sorbent kinetics data into a daily yield of captured water demonstrated (i) the existence of an optimal open porosity for each sorbent, (ii) that thinner layers with moderate open porosity performed respectively better than thicker layers with high open porosity, and (iii) that high maximum water uptake and fast single-particle kinetics are not necessarily predictive of high daily water yield

Sulfur-rich organic films deposited by plasma- and vacuum-ultraviolet (VUV) photo-polymerization

Thiol (SH)-terminated surfaces have been progressively gaining interest over the past years as a consequence of their widespread potential applications. Here, SH-terminated thin films have been prepared by “co-polymerizing” gas mixtures comprising ethylene (C2H4) or butadiene (C4H6) with hydrogen sulfide (H2S). This has been accomplished by either vacuum-ultraviolet (VUV) irradiation of the flowing gas mixtures with near-monochromatic radiation from a Kr lamp, or by low-pressure r.f. plasma-enhanced chemical vapor deposition (PECVD). Varying the gas mixture ratio, R, allows one to control the films’ sulfur content as well as the thiol concentration [[BOND]SH]. The deposits were characterized by X-ray photoelectron spectroscopy (XPS), before and after chemical derivatization with N-ethylmaleimide, and by ATR FTIR. VUV- and plasma-prepared coatings were found to possess very similar structures and characteristics, showing chemically bonded sulfur concentrations, [S], up to 48 at% and [[BOND]SH] up to 3%. All coatings remained essentially unchanged in thickness after immersion in water for 24 h

Effect of nitrogen-rich cell culture surfaces on type X collagen expression by bovine growth plate chondrocytes

Background: Recent evidence indicates that osteoarthritis (OA) may be a systemic disease since mesenchymal stem cells (MSCs) from OA patients express type X collagen, a marker of late stage chondrocyte hypertrophy (associated with endochondral ossification). We recently showed that the expression of type X collagen was suppressed when MSCs from OA patients were cultured on nitrogen (N)-rich plasma polymer layers, which we call "PPE:N" (N-doped plasma-polymerized ethylene, containing up to 36 atomic percentage (at.%) of N.Methods: In the present study, we examined the expression of type X collagen in fetal bovine growth plate chondrocytes (containing hypertrophic chondrocytes) cultured on PPE:N. We also studied the effect of PPE: N on the expression of matrix molecules such as type II collagen and aggrecan, as well as on proteases (matrix metalloproteinase-13 (MMP-13) and molecules implicated in cell division (cyclin B2). Two other culture surfaces, "hydrophilic" polystyrene (PS, regular culture dishes) and nitrogen-containing cation polystyrene (Primaria (R)), were also investigated for comparison.Results: Results showed that type X collagen mRNA levels were suppressed when cultured for 4 days on PPE: N, suggesting that type X collagen is regulated similarly in hypertrophic chondrocytes and in human MSCs from OA patients. However, the levels of type X collagen mRNA almost returned to control value after 20 days in culture on these surfaces. Culture on the various surfaces had no significant effects on type II collagen, aggrecan, MMP-13, and cyclin B2 mRNA levels.Conclusion: Hypertrophy is diminished by culturing growth plate chondrocytes on nitrogen-rich surfaces, a mechanism that is beneficial for MSC chondrogenesis. Furthermore, one major advantage of such "intelligent surfaces" over recombinant growth factors for tissue engineering and cartilage repair is potentially large cost-saving

Growth mechanisms of sulfur-rich plasma polymers: Binary gas mixtures versus single precursor

Thiol (SH)‐terminated surfaces have gained interest over the past years due to their potential applications, especially in the biomedical field. In this work, SH‐terminated films have been prepared by “co‐polymerizing” gas mixtures of acetylene (C2H2) and hydrogen sulfide (H2S) using low‐pressure r.f. plasma‐enhanced chemical vapor deposition. R.f. power greatly influences the deposition rate, sulfur content, [S], and thiol concentration, [SH], of the films, as confirmed by XPS (both before and after chemical derivatization), FTIR, and mass spectrometry measurements. These data are compared with those obtained in a similar discharge by using a single molecule precursor, propanethiol. Among other differences, it is demonstrated that [SH] is higher when using binary gas mixtures compared to the single molecule precursor

Organic coatings from acetylene at atmospheric pressure: UV light versus plasma

ABSTRACT: A versatile pilot-scale reactor has been designed in such a way that it can be readily converted from a dielectric barrier discharge “PECVD” operating mode into a photoinitiated “PICVD” one; in the latter, low-pressure mercury (Hg) lamps replace the high-voltage glow discharge plasma. Both processes operate at ambient temperature and atmospheric pressure, 100 kPa, using acetylene (C2H2) monomer. In both sets of experiments, it was found that efficient gas-to-solid conversion can occur in the form of a nanoparticulate amorphous hydrocarbon polymer-like material. It was found that in the PICVD case, great care was required to exclude even traces of O2 contamination, because it not only reduced the growth rate of solid, but the latter then became highly oxidized ([O] ~50 at.%) and water-soluble

The effect of novel nitrogen-rich plasma polymer coatings on the phenotypic profile of notochordal cells

Background: The loss of the notochordal cells from the nucleus pulposus is associated with ageing and disc degeneration. However, understanding the mechanisms responsible for the loss of these cells has been hampered in part due to the difficulty of culturing and maintaining their phenotype. Furthermore, little is known about the influence of the substratum on the molecular markers of notochordal cells. Methods: Notochordal cells were isolated from lumbar spine of non-chondrodystrophoid dogs and cultured on N-rich plasma polymer layers, so-called "PPE:N" ( N-doped plasma-polymerised ethylene, containing up to 36% [N]) surfaces, for 3, 7 or 14 days. Gene expression of vimentin ( VIM), pleiotrophin ( PTN), matrix Gla protein ( MGP), cartilage oligomeric matrix protein ( COMP), keratin 18 ( KRT 18), aggrecan ( AGG), collagen type 1 ( COL1A2), collagen type 2 ( COL2A1) was analyzed through semi-quantitative reverse transcription-polymerase chain reaction ( RT-PCR).Results: Notochordal cells were maintained in culture on PPE:N for up to 14 days with no loss in cell viability. Except for VIM, gene expression varied depending on the culture periods and [ N] concentration of the substratum. Generally, PPE: N surfaces altered gene expression significantly when cells were cultured for 3 or 7 days.Conclusion: The present study has shown that notochordal cells from dogs can attach to and grow on PPE: N surfaces. Analysis of the expression of different genes in these cells cultured on different N-functionalized surfaces indicates that cellular behaviour is gene-specific and time-dependent. Further studies are required to better understand the roles of specific surface functionalities on receptor sites, and their effects on cellular phenotypes