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Personne :
Laroche, Gaétan

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Laroche

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Gaétan

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Université Laval. Département de génie des mines, de la métallurgie et des matériaux

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ncf10316941

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  • PublicationAccès libre
    Design, degradation mechanism and long-term cytotoxicity of poly(L-lactide) and poly(lactide-co-ε-caprolactone) terpolymer film and air-spun nanofiber scaffold
    (Wiley Online Library, 2015-06-08) Laroche, Gaétan; Larrañaga, Aitor; Guay-Bégin, Andrée-Anne; Sabbatier, Gad; Fernandez, Jorge; Diéval, Florence; Durand, Bernard; Sarasua, Jose-Ramon
    Degradable nanofiber scaffold is known to provide a suitable, versatile and temporary structure for tissue regeneration. However, synthetic nanofiber scaffold must be properly designed to display appropriate tissue response during the degradation process. In this context, this publication focuses on the design of a finely-tuned poly(lactide-co-e-caprolactone) terpolymer (PLCL) that may be appropriate for vascular biomaterials applications and its comparison with well-known semi-crystalline poly(L-lactide) (PLLA). The degradation mechanism of polymer film and nanofiber scaffold and endothelial cells behavior cultured with degradation products is elucidated. The results highlight benefits of using PLCL terpolymer as vascular biomaterial compared to PLLA.
  • PublicationAccès libre
    Evaluating poly(Acrylamide-co-Acrylic Acid) hydrogels stress relaxation to direct the osteogenic differentiation of mesenchymal stem cells
    (Wiley, 2021-04-19) Prouvé, Émilie; Drouin, Bernard; Laroche, Gaétan; Rémy-Zolghadri, Murielle; Chevallier, Pascale; Durrieu, Marie-Christine
    The aim of this study is to investigate polyacrylamide-based hydrogels stress relaxation and the subsequent impact on the osteogenic differentiation of human mesenchymal stem cells (hMSCs). Different hydrogels are synthesized by varying the amount of cross-linker and the ratio between the monomers (acrylamide and acrylic acid), and characterized by compression tests. It has been found that hydrogels containing 18% of acrylic acid exhibit an average relaxation of 70%, while pure polyacrylamide gels show an average relaxation of 15%. Subsequently, hMSCs are cultured on two different hydrogels functionalized with a mimetic peptide of the bone morphogenetic protein-2 to enable cell adhesion and favor their osteogenic differentiation. Phalloidin staining shows that for a constant stiffness of 55 kPa, a hydrogel with a low relaxation (15%) leads to star-shaped cells, which is typical of osteocytes, while a hydrogel with a high relaxation (70%) presents cells with a polygonal shape characteristic of osteoblasts. Immunofluorescence labeling of E11, strongly expressed in early osteocytes, also shows a dramatically higher expression for cells cultured on the hydrogel with low relaxation (15%). These results clearly demonstrate that, by fine-tuning hydrogels stress relaxation, hMSCs differentiation can be directed toward osteoblasts, and even osteocytes, which is particularly rare in vitro.
  • 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
    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
    Directing hMSCs fate through geometrical cues and mimetics peptides
    (John Wiley & Sons, 2019-10-08) Padiolleau, Laurence; Laroche, Gaétan
    The native microenvironment of mesenchymal stem cells (hMSCs)—the extracellular matrix (ECM), is a complex and heterogenous environment structured at different scales. The present study aims at mimicking the hierarchical microorganization of proteins or growth factors within the ECM using the photolithography technique. Polyethylene terephthalate substrates were used as a model material to geometrically defined regions of RGD + BMP‐2 or RDG + OGP mimetic peptides. These ECM‐derived ligands are under research for regulation of mesenchymal stem cells osteogenic differentiation in a synergic manner. The hMSCs osteogenic differentiation was significantly affected by the spatial distribution of dually grafted peptides on surfaces, and hMSCs cells reacted differently according to the shape and size of peptide micropatterns. Our study demonstrates the presence of a strong interplay between peptide geometric cues and stem cell differentiation toward the osteoblastic lineage. These tethered surfaces provide valuable tools to investigate stem cell fate mechanisms regulated by multiple ECM cues, thereby contributing to the design of new biomaterials and improving hMSCs differentiation cues.
  • PublicationAccès libre
    Human saphenous vein endothelial cell adhesion and expansion on micropatterned polytetrafluoroethylene
    (Wiley, 2012-08-31) Boivin, Marie-Claude; Laroche, Gaétan; Hoesli, Corinne A.; Lagueux, Jean; Bareille, Reine; Rémy-Zolghadri, Murielle; Chevallier, Pascale; Bordenave, Laurence; Durrieu, Marie-Christine
    Intimal hyperplasia and thrombosis are responsible for the poor patency rates of small-diameter vascular grafts. These complications could be avoided by a rapid and strong adhesion of endothelial cells to the prosthetic surfaces, which typically consist of expanded polytetrafluoroethylene (PTFE) for small-diameter vessels. We have previously described two peptide micropatterning strategies that increase the endothelialization rates of PTFE. The micropatterns were generated either by inkjet printing 300 μm squares or by spraying 10.1 ± 0.1 μm diameter droplets of the CGRGDS cell adhesion peptide, while the remaining surface was functionalized using the CWQPPRARI cell migration peptide. We now directly compare these two micropatterning strategies and examine the effect of hydrodynamic stress on human saphenous vein endothelial cells grown on the patterned surfaces. No significant differences in cell adhesion were observed between the two micropatterning methods. When compared to unpatterned surfaces treated with a uniform mixture of the two peptides, the cell expansion was significantly higher on sprayed or printed surfaces after 9 days of static cell culture. In addition, after 6 h of exposure to hydrodynamic stress, the cell retention and cell cytoskeleton reorganization on the patterned surfaces was improved when compared to untreated or random treated surfaces. These results indicate that micropatterned surfaces lead to improved rates of PTFE endothelialization with higher resistance to hydrodynamic stress.
  • 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
    A comparative study between human skin substitutes and normal human skin using Raman microspectroscopy
    (Minerals, Metals and Materials Society, 2014-02-12) Labbé, Jean-François; Jean, Jessica; Auger, Michèle; Ouellet, Marise; Laroche, Gaétan; Leroy, Marie; Pouliot, Roxane; Lefèvre, Thierry
    Research in the field of bioengineered skin substitutes is motivated by the need to find new dressings for people affected by skin injuries (burns, diabetic ulcers), and to develop adequate skin models to test new formulations developed in vitro. Thanks to advances in tissue engineering, it is now possible to produce human skin substitutes without any exogenous material, using the self-assembly method developed by the Laboratoire d’Organogénèse Expérimentale. These human skin substitutes consist of a dermis and a stratified epidermis (stratum corneum and living epidermis). Raman microspectroscopy has been used to characterize and compare the molecular organization of skin substitutes with normal human skin. Our results confirm that the stratum corneum is a layer rich in lipids which are well ordered (trans conformers) in both substitutes and normal human skin. The amount of lipids decreases and more gauche conformers appear in the living epidermis in both cases. However, the results also show that there are fewer lipids in the substitutes and that the lipids are more organized in the normal human skin. Concerning the secondary structure of proteins and protein content, the data show that they are similar in the substitutes and in the normal human skin. In fact, the epidermis is rich in α-keratin, whereas the dermis contains mainly type I collagen.
  • 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).
  • PublicationAccès libre
    FTIR-ATR spectroscopy in thin film studies : the importance of sampling depth and deposition substrate
    (Elsevier, 2013-02-27) Laroche, Gaétan; Fitremann, Juliette; Gherardi, Nicolas
    Fourier transform infrared (FTIR) spectroscopy in the attenuated total reflectance mode (ATR) was used to characterise SiOxHy thin films deposited on either polypropylene foil or silicon wafers through a cold atmospheric plasma discharge. Compared to a classical transmission spectrum with transverse (TO) vibrational modes, the FTIR-ATR spectra revealed modified and/or exhibited additional features caused by either the non-orthogonal angle of incidence of the infrared radiation with respect to the sample normal or the partial light reflection on the deposition substrate. On one hand, recording the infrared spectra with an angle of incidence other than 90° produced a longitudinal (perpendicular to the sample normal) component in the electric field of the incident light, which enabled the detection of longitudinal (LO) vibrational modes. On the other hand, the transverse vibrational modes of thin films deposited on silicon were slightly extinguished with a concomitant increase of the spectral intensity of the LO features, due to both the partial withdrawing between the incident and reflected electric fields of the infrared light lying in the sample plane and, the addition of those perpendicular to this sample plane. These data thus clearly show the enormous potential of FTIR-ATR to characterise thin film molecular order, provided that a prior comprehensive analysis is performed on the sampling depth and the light reflection on the deposition substrate