Personne :
Laroche, Gaétan

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Université Laval. Département de génie des mines, de la métallurgie et des matériaux
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  • PublicationAccès libre
    RGD and BMP-2 mimetic peptides crosstalk enhances osteogenic commitment of human bone marrow stem cells
    (Elsevier, 2016-03-18) Bilem, Ibrahim; Laroche, Gaétan; Plawinski, Laurent; Chevallier, Pascale; Stone, E.; Durrieu, Marie-Christine
    Human bone marrow mesenchymal stem cells (hBMSCs) commitment and differentiation are dictated by bioactive molecules sequestered within their Extra Cellular Matrix (ECM). One common approach to mimic the physiological environment is to functionalize biomaterial surfaces with ECM-derived peptides able to recruit stem cells and trigger their linage-specific differentiation. The objective of this work was to investigate combinatorial effects of RGD and BMP-2 mimetic peptides on the osteogenic commitment of hBMSCs, without supplementing the media with pro-osteogenic factors. The RGD peptide promotes cell adhesion via cell transmembrane integrin receptors, while the BMP-2 peptide, corresponding to residues 73-92 of Bone Morphogenetic Protein-2, was shown to induce hBMSCs osteoblast differentiation. The immobilization of peptides on aminated glass was ascertained by X-ray Photoelectron Spectroscopy (XPS), the density of grafted peptides was quantified by fluorescence microscopy and the surface roughness was evaluated using Atomic Force Microscopy (AFM). The osteogenic commitment of hBMSCs cultured on RGD and/or BMP-2 surfaces was characterized by immunohistochemistry using STRO-1 as specific stem cells marker and Runx-2 as an earlier osteogenic marker. Biological results showed that the osteogenic commitment of hBMSCs was enhanced on bifunctionalized surfaces as compared to surfaces containing BMP-2, while on RGD surfaces cells mainly preserved their stemness character. These results demonstrated that RGD and BMP-2 mimetic peptides act synergistically to enhance hBMSCs osteogenesis without supplementing the media with osteogenic factors. These findings contribute to the development of biomimetic materials, allowing a deeper understanding of signaling pathways that govern the transition of stem cells towards the osteoblastic lineage.
  • PublicationAccès libre
    Rapid nucleation of iron oxide nanoclusters in aqueous solution by plasma electrochemistry
    (ACS Publications, 2015-06-18) Turgeon, Stéphane; Fortin, Marc-André; Laroche, Gaétan; Sarra-Bournet, Christian; Lagueux, Jean; Létourneau, Mathieu; Chevallier, Pascale; Laprise-Pelletier, Myriam; Bouchard, Mathieu
    Progresses in cold atmospheric plasma technologies have made possible the synthesis of nanoparticles in aqueous solutions using plasma electrochemistry principles. In this contribution, a reactor based on microhollow cathodes and operating at atmospheric pressure was developed to synthesize iron-based nanoclusters (nanoparticles). Argon plasma discharges are generated at the tip of the microhollow cathodes, which are placed near the surface of an aqueous solution containing iron salts (FeCl₂ and FeCl₃) and surfactants (biocompatible dextran). Upon reaction at the plasma−liquid interface, reduction processes occur and lead to the nucleation of ultrasmall iron-based nanoclusters (IONCs). The purified IONCs were investigated by XPS and FTIR, which confirmed that the nucleated clusters contain a highly hydrated form of iron oxide, close to the stoichiometric constituents of α-FeOOH (goethite) or Fe₅O₃(OH)₉ (ferrihydrite). Relaxivity values of r₁ = 0.40 mM−¹ s−¹ and r₂/r₁ = 1.35 were measured (at 1.41 T); these are intermediate values between the relaxometric properties of superparamagnetic iron oxide nanoparticles used in medicine (USPIO) and those of ferritin, an endogenous contrast agent. Plasma-synthesized IONCs were injected into the mouse model and provided positive vascular signal enhancement in T₁-w. MRI for a period of 10−20 min. Indications of rapid and strong elimination through the urinary and gastrointestinal tracts were also found. This study is the first to report on the development of a compact reactor suitable for the synthesis of MRI iron-based contrast media solutions, on site and upon demand.
  • PublicationAccès libre
    Deposition of anti-fog coatings on glass substrates using the jet of an open-to-air microwave argon plasma at atmospheric pressure
    (Wiley-VCH-Verl., 2020-04-22) Durocher-Jean, Antoine; Rodríguez Durán, Iván; Asadollahi, Siavash; Laroche, Gaétan; Stafford, Luc
    This study reports a one-step process for the formation of anti-fog coatings on commercial glass substrates using the jet of an open-to-air microwave argon plasma at atmospheric pressure with hexamethyldisiloxane (HMDSO) as the precursor for plasma-enhanced chemical vapor deposition. Optical microscopy and broadband light transmittance measurements revealed significant precursor fragmentation and gas phase association reactions when HMDSO was injected close to the tube outlet, resulting in powder-like, hydrophobic, and semiopaque glass surfaces. On the contrary, injection of HMDSO close to the substrate led to smoother, homogeneous, hydrophilic, and transparent glass surfaces. In addition, transmittance measurements at 590 nm in humid air according to American Society for Testing and Materials standard tests revealed superior antifogging properties to plasma-treated glass substrates. On the basis of the optical emission and absorption spectroscopy measurements, electrons, metastable argon atoms, and hot neutral argon atoms were mostly responsible for the significant precursor fragmentation close to the tube outlet, whereas the contribution of hot neutrals and ultraviolet photons became important close to the substrate.
  • PublicationAccès libre
    Fibronectin grafting to enhance skin sealing around transcutaneous titanium implant
    (John Wiley & Sons, 2021-04-30) Bilem, Ibrahim; Ghadhab, Souhaila; Ruel, Jean; Laroche, Gaétan; Auger, François A.; Guay-Bégin, Andrée-Anne; Pauthe, Emmanuel; Chevallier, Pascale
    Intraosseous transcutaneous amputation prosthesis is a new approach in orthopedic implants that overcomes socket prosthesis problems. Its long-term performance requires a tight skin-implant seal to prevent infections. In this study, fibronectin (Fn), a widely used adhesion protein, was adsorbed or grafted onto titanium alloy. Fn grafting was performed using two different linking arms, dopamine/glutaric anhydride or phosphonate. The characterization of Fn-modified surfaces showed that Fn grating via phosphonate has led to the highest amount of Fn cell-binding site (RGD, arginine, glycine, and aspartate) available on the surface. Interestingly, cell culture studies revealed a strong correlation between the amount of available RGD ligands and cellular behavior, since enhanced proliferation and spreading of fibroblasts were noticed on Fn-grafted surfaces via phosphonate. In addition, an original in vitro mechanical test, inspired from the real situation, to better predict clinical outcomes after implant insertion, has been developed. Tensile test data showed that the adhesion strength of a bio-engineered dermal tissue was significantly higher around Fn-grafted surfaces via phosphonate, as compared to untreated surfaces. This study sheds light on the importance of an appropriate selection of the linking arm to tightly control the spatial conformation of biomolecules on the material surface, and consequently cell interactions at the interface tissue/implant.
  • PublicationAccès libre
    Fourier-Transform infrared spectroscopy of ethyl lactate decomposition and thin-film coating in a filamentary and a glow dielectric barrier discharge
    (Wiley-VCH-Verl., 2021-07-05) Milaniak, Natalia; Laroche, Gaétan; Massines, Françoise
    Glow and filamentary regimes of atmospheric pressure plasma-enhanced chemical vapor deposition in a planar dielectric barrier discharge configuration were compared for thin-film deposition from ethyl lactate (EL). EL decomposition in the plasma phase and thin-film composition were both characterized by Fourier- transform infrared spectroscopy. EL chemical bonds' concentration along the gas flow decreases progressively in the glow dielectric barrier discharge (GDBD), whereas it drastically oscillates in the filamentary dielectric barrier discharge (FDBD), with values higher than that of the initial mixture. EL decomposition route depends on the discharge regime, as the decrease of the concentration of the different investigated bonds is different for an identical amount of energy provided to EL molecules. CO2 is systematically formed reaching concentrations of 25 and 40 ppm, respectively, in FDBD and GDBD.
  • PublicationAccès libre
    Characterization of argon dielectric barrier discharges applied to ethyl lactate plasma polymerization
    (Institute of Physics Publishing Ltd, 2017-11-03) Laroche, Gaétan; Desjardins, Edouard; Naudé, Nicolas; Meichelboeck, Maximilian; Laurent, Morgane; Stafford, Luc; Gherardi, Nicolas
    The influence of the input voltage frequency (35 and 150 kHz), interelectrode gap (1 and 2 mm) and precursor concentration (250, 350, and 450 ppm) on the electron temperature (Te), number density of metastable Ar atoms (n(Arm)), and discharge current density (proportional to the electron density ne) is studied in an argon-ethyl lactate dielectric barrier discharge (DBD). An argon-ammonia Penning mixture is also considered as reference. These results are correlated to the chemistry (XPS, IR) and topography (AFM) of the ethyl-lactate-based plasma polymer coatings. Low Te values from 0.3 to 0.5 eV were obtained for all discharges. This observation, in addition to resemblances with the Ar–NH3 mixture, suggested that the ionization kinetics of ethyl lactate-based discharges is driven by Penning reactions. Among the investigated parameters, the dissipated power obtained through changes of the excitation frequency had the largest impact on both the coatings properties and the discharge behavior.
  • PublicationAccès libre
    Atmospheric pressure cold plasma versus wet-chemical surface treatments for carboxyl functionalization of polylactic acid : a first step toward the immobilization of bioactive molecules
    (Elsevier, 2020-02-08) Laroche, Gaétan; Rodríguez Durán, Iván; Vanslambrouck, Stéphanie; Chevallier, Pascale
    The use of polylactic acid (PLA) has attracted growing interest, particularly in recent years, for biomedical applications because of its mechanical properties, biocompatibility, and biodegradability. Despite this, features such as surface hydrophobicity and the absence of suitable functional groups for covalent immobilization of bioactive molecules, make it challenging to endow PLA-based medical devices with additional features and thus broaden their range of applicability. In the present study, we demonstrate the suitability of atmospheric pressure dielectric barrier discharges operating in the Townsend regime as a promising alternative to other surface treatments, such as diazonium and alkali hydrolytic treatments, for carboxyl functionalization of PLA. Chemical changes in PLA surfaces are evaluated by contact angle measurements and by X-ray photoelectron spectroscopy while physical changes are investigated by scanning electron microscopy and atomic force microscopy. The amount of carboxyl groups generated on PLA surfaces is assessed by toluidine blue O assay and substantiated by grafting, through carboxyl groups, a fluorescent probe containing amino functionalities. All of the surface treatments have proven to be very effective in generating carboxylic groups on the PLA surface. Nevertheless, plasma treatment is shown to not degrade the PLA surface, in sharp contrast with diazonium and alkali hydrolytic treatments.
  • PublicationAccès libre
    A fluorophore-tagged RGD peptide to control endothelial cell adhesion to micropatterned surfaces
    (ScienceDirect, 2013-10-31) Hoesli, Corinne A.; Duchesne, Carl; Juneau, Pierre-Marc; Laroche, Gaétan; Chevallier, Pascale
    The long-term patency rates of vascular grafts and stents are limited by the lack of surface endothelialisation of the implanted materials. We have previously reported that GRGDS and WQPPRARI peptide micropatterns increase the endothelialisation of prosthetic materials in vitro. To investigate the mechanisms by which the peptide micropatterns affect endothelial cell adhesion and proliferation, a TAMRA fluorophore-tagged RGD peptide was designed. Live cell imaging revealed that the micropatterned surfaces led to directional cell spreading dependent on the location of the RGD-TAMRA spots. Focal adhesions formed within 3 h on the micropatterned surfaces near RGD-TAMRA spot edges, as expected for cell regions experiencing high tension. Similar levels of focal adhesion kinase phosphorylation were observed after 3 h on the micropatterned surfaces and on surfaces treated with RGD-TAMRA alone, suggesting that partial RGD surface coverage is sufficient to elicit integrin signaling. Lastly, endothelial cell expansion was achieved in serum-free conditions on gelatin-coated, RGD-TAMRA treated or micropatterned surfaces. These results show that these peptide micropatterns mainly impacted cell adhesion kinetics rather than cell proliferation. This insight will be useful for the optimization of micropatterning strategies to improve vascular biomaterials.
  • PublicationAccès libre
    Milkweed scaffold : a new candidate for bone cell growth
    (Taylor & Francis Online, 2019-06-17) Bilem, Ibrahim; Laroche, Gaétan; Naudé, Nicolas; Elkoun, S.; Chevallier, Pascale; Robert, Mathieu; Soulié, Simon
    This study aims to evaluate the potential of milkweed as potential candidate to construct biodegradable scaffold for bone regeneration. A mat made of milkweed, polyethylene, and polypropylene was treated with an atmospheric pressure plasma to functionalize the surface of the polymer assembly with carboxylic acid groups, which enable to conjugate bioactive molecules, while accelerating the degradation of milkweed. Degradation tests demonstrated substantial decrease of the weight of the treated polymer mat as compared to untreated one. Biological assays revealed that the polymer assembly promoted preosteoblast MC3T3 cells recruitment with a significant enhancement observed on the RGD-grafted polymer mat.
  • PublicationAccès libre
    Atmospheric pressure townsend discharges as a promising tool for the one‐step deposition of antifogging coatings from N2O/TMCTS mixtures
    (Wiley, 2020-02-13) Laroche, Gaétan; Durocher-Jean, Antoine; Rodríguez Durán, Iván; Profili, Jacopo; Stafford, Luc
    The need to ensuring the “see‐through” property of transparent materials when exposed to sudden temperature changes or very humid conditions has encouraged the development of antifogging strategies, such as the deposition of (super)hydrophilic coatings. However, despite the effectiveness of these coatings in combating the effects of fogging, most of the coating techniques explored to date are typically time‐consuming and environment‐unfriendly. Bearing this in mind, we demonstrate that the application of dielectric barrier discharges operated at atmospheric pressure proves to be successful in preparing antifogging coatings on glass samples from 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS) and nitrous oxide (N2O). The antifogging performance of the coatings was found to be governed by the [N2O]/[TMCTS] ratio and not by the [N2O] + [TMCTS] sum. Coatings prepared under a [N2O]/[TMCTS] = 30 were superhydrophilic (water contact angles ≈ 5°–10°) due to surface silanol groups and endowed glass samples with a superior antifogging property, as revealed by the ASTM F 659‐06 test. In contrast, because of the lesser hydrophilicity (water contact angles ≈ 60°), coatings prepared under a [N2O]/[TMCTS] = 10 did not endow glass samples with antifogging property. Regardless of the deposition conditions, the plasma‐deposited coatings displayed crack‐free smooth surfaces (Rrms = 2−4 nm).