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Boudreau, Denis

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Boudreau
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Denis
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Université Laval. Département de chimie
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Résultats de recherche

Voici les éléments 1 - 10 sur 14
  • Publication
    Restreint
    Correlating metal-enhanced fluorescence and sructural properties in Ag@SiO2 core-shell nanoparticles
    (Springer Science + Business Media, 2016-03-12) Asselin, Jérémie; Legros, Philippe; Boudreau, Denis; Grégoire, Alexandre
    Metal@silica concentric nanoparticles capable of metal-enhanced fluorescence (MEF) represent a powerful means to improve the brightness and stability of encapsulated organic fluorophores and are finding numerous applications in biology, analytical chemistry, and medical diagnostics. The rational design of MEF-enabled labels and sensors often involves comparing fluorescence enhancement factors (EF) between nanostructures having different structural properties (e.g., metal core diameter, silica shell thickness, extent of spectral overlap between plasmon band and fluorophore). Accurate determination of EFs requires the measurement of fluorescence emission intensity in the presence and absence of the plasmonic core while minimizing the impact of physical and chemical artifacts (e.g., signal variations due to scattering, adsorption, sedimentation). In this work, Ag@SiO2@SiO2¿+¿x (where x is fluorescein, eosin, or rhodamine B) nanostructures were synthesized with excellent control of core size, silica spacer shell thickness and fluorophore concentration. Using UV-VIS spectrometry, spectrofluorimetry, time-resolved fluorometry, and transmission electron microscopy, we investigated the influence of these key structural factors on fluorescence emission intensity, and the results were used to develop a generalized methodology for the determination of fluorescence enhancement factors in Ag@SiO2 core-shell nanoparticles. This methodology should be of general importance to designing MEF-enabled nanostructures, sensors, and related analytical techniques.
  • Publication
    Restreint
    Carbonic anhydrase XII in valve interstitial cells promotes the regression of calcific aortic valve stenosis.
    (Academic Press Inc, Ltd., 2016-03-11) Lachance, Dominic.; Bouchareb, Rihab; Asselin, Jérémie; Boudreau, Denis; Marette, André.; Boulanger, Marie-Chloé; Le Quang, Khai; Côté, Nancy.; Bossé, Yohan; Shayhidin, Elnur Elyar; Messaddeq, Younès; El Husseini, Diala; Mahmut, Ablajan; Pibarot, Philippe; Hadji, Fayez; Mathieu, Patrick
    Aims: Calcific aortic valve stenosis (CAVS) is the most common heart valve disease. In the present work we sought to determine the reversibility of mineralization in the aortic valve. Methods and results: By using in vitro analyses we found that valve interstitial cells (VICs) have the ability to resorb minerals. We documented that agonist of P2Y2 receptor (P2Y2R) promoted the expression of carbonic anhydrase XII (CAXII) at the cell membrane of VICs, whereby minerals are resorbed. P2Y2R-mediated mineral resorption was corroborated by using mouse VICs isolated from wild type and P2Y2R-/- mice. Measurements of extracellular pH (pHe) by using core–shell nanosensors revealed that P2Y2R-mediated CAXII export to the cell membrane led to an acidification of extracellular space, whereby minerals are resorbed. In vivo, we next treated LDLR-/-/ApoB100/100/IGF2 mice, which had developed CAVS under a high-fat/high-sucrose diet for 8 months, with 2-thioUTP (a P2Y2R agonist) or saline for the next 2 months. The administration of 2-thioUTP (2 mg/kg/day i.p.) reduced the mineral volume in the aortic valve measured with serial microCT analyses, which improved hemodynamics and reduced left ventricular hypertrophy (LVH). Examination of leaflets at necropsy confirmed a lower level of mineralization and fibrosis along with higher levels of CAXII in mice under 2-thioUTP. In another series of experiment, the administration of acetazolamide (a CA inhibitor) prevented the acidification of leaflets and the regression of CAVS induced by 2-thioUTP in LDLR-/-/ApoB100/100/IGF2 mice. Conclusion: P2Y2R-mediated expression of CAXII by VICs acidifies the extracellular space and promotes the regression of CAVS.
  • Publication
    Accès libre
    Nucleation points : the forgotten parameter in the synthesis of hydrogel-coated gold nanoparticles
    (Basel, 2021-01-26) Sepulveda, Adolfo; Picard-Lafond, Audrey; Boudreau, Denis; Marette, André.
    The implementation of gold-hydrogel core-shell nanomaterials in novel light-driven technologies requires the development of well-controlled and scalable synthesis protocols with precisely tunable properties. Herein, new insights are presented concerning the importance of using the concentration of gold cores as a control parameter in the seeded precipitation polymerization process to modulate—regardless of core size—relevant fabrication parameters such as encapsulation yield, particle size and shrinkage capacity. Controlling the number of nucleation points results in the facile tuning of the encapsulation process, with yields reaching 99% of gold cores even when using different core sizes at a given particle concentration. This demonstration is extended to the encapsulation of bimodal gold core mixtures with equally precise control on the encapsulation yield, suggesting that this principle could be extended to encapsulating cores composed of other materials. These findings could have a significant impact on the development of stimuli-responsive smart materials.
  • Publication
    Accès libre
    Revealing the hydrolysis mechanism of a Hg2+-reactive fluorescein probe : novel insights on thionocarbonated dyes
    (American Chemical Society, 2019-12-31) Picard-Lafond, Audrey; Boudreau, Denis; Larivière, Dominic
    As one of the most toxic metal pollutants, mercury is the subject of extensive research to improve current detection strategies, notably to develop sensitive, selective, fast, and affordable Hg2+-responsive fluorescent probes. Comprehending the sensing mechanism of these molecules is a crucial step in their design and optimization of their performance. Herein, a new fluorescein-based thionocarbonate-appended Hg2+-sensitive probe was synthesized to study the hydrolysis reactions involved in the sensing process. Autohydrolysis was revealed as a significant component of the signal generation mechanism, occurring concurrently with Hg2+-catalyzed hydrolysis. This knowledge was used to investigate the effects of key experimental conditions (pH, temperature, chloride ions) on sensing efficiency. Overall, the chemical and physical properties of this new thionocarbonated dye and the insights into its sensing mechanism will be instrumental in designing reliable and effective portable sensing strategies for mercury and other heavy metals.
  • Publication
    Accès libre
    Acting as a molecular tailor : dye structural modifications for improved sensitivity towards lysophosphatidic acids sensing
    (American Chemiscal Society, 2022-12-28) Fontaine, Nicolas; Harter, Lara; Marette, André.; Boudreau, Denis
    Lysophosphatidic acids (LPA) are key biomarkers for several physiological processes, the monitoring of which can provide insights into the host’s health. Common lab-based techniques for their detection are cumbersome, expensive and necessitate specialized personnel to operate. LPA-sensitive fluorescent probes have been described, albeit for non-aqueous conditions, which impedes their use in biological matrices. In this paper, we explore in detail the influence of structure on the extent of aggregation-induced fluorescence quenching using specially synthesized styrylpyridinium dyes bearing structural adaptations to bestow them enhanced affinity towards LPA in aqueous media. Spectroscopic investigations supported by time-resolved fluorimetry revealed the contribution of excimer formation to the fluorescence quenching mechanism displayed by the fluorescent probes. Experimental observations of the influence of structure on detection sensitivity were supported by DFT calculations.
  • Publication
    Accès libre
    A glycan-based plasmonic sensor for prostate cancer diagnosis
    (Royal Society of Chemistry, 2021-10-01) Lamarre, Mathieu; Bansept, Marc-Antoine; Boudreau, Denis; Tremblay, Thomas; Fradet, Vincent; Giguère, Denis; Robitaille, Karine
    Prostate cancer affects thousands of men who undergo clinical screening tests every year. The main biomarker used for the diagnosis of prostate cancer, prostate specific antigen (PSA), presents limitations that justify investigating new biomarkers to improve reliability. Antibodies against the tumor-associated carbohydrate antigen (Tn), or TACA, develop early in carcinogenesis, making them an interesting alternative as a target for prostate cancer diagnostics. In this work, the Tn antigen was synthesized and immobilized on a surface plasmon resonance sensor coated with a polydopamine/polyethylene oxide mixed layer used both as an anchoring surface for Tn capture moieties and to minimize surface fouling. The sensor could be regenerated and reused at least 60 times without any significant loss in sensitivity. Anti-Tn antibodies were detected in the 0-10 nM concentration range with detection limits of 0.1 and 0.3 nM in spiked buffer solutions and diluted human blood serum samples, respectively. Finally, as a proof-of-concept, this carbohydrate-based sensor was used to successfully discriminate blood serum samples from prostate cancer-free and prostate cancer patients.
  • Publication
    Accès libre
    Pushing the limits of surface-enhanced raman spectroscopy (SERS) with deep learning : identification of multiple species with closely related molecular structures
    (Society for Applied Spectroscopy, 2022-01-26) Boudreau, Denis; Fillion, Daniel; Fontaine, Nicolas; Fortin, Hubert; Lebrun, Alexis; Barbier, Olivier
    Raman spectroscopy is a non-destructive and label-free molecular identification technique capable of producing highly specific spectra with various bands correlated to molecular structure. Moreover, the enhanced detection sensitivity offered by Surface-Enhanced Raman spectroscopy (SERS) allows analyzing mixtures of related chemical species in a relatively short measurement time. Combining SERS with deep learning algorithms allows in some cases to increase detection and classification capabilities even further. The present study evaluates the potential of applying deep learning algorithms to SERS spectroscopy to differentiate and classify different species of bile acids, a large family of molecules with low Raman cross sections and molecular structures that often differ by a single hydroxyl group. Moreover, the study of these molecules is of interest for the medical community since they have distinct pathological roles and are currently viewed as potential markers of gut microbiome imbalances. A Convolutional Neural Network (CNN) model was developed and used to classify SERS spectra from five bile acid species. The model succeeded in identifying the five analytes despite very similar molecular structures and was found to be reliable even at low analyte concentrations.
  • Publication
    Accès libre
    Thinking outside the shell : novel sensors designed from plasmon-enhanced fluorescent concentric nanoparticles
    (Cambridge Royal Society of Chemistry, 2020-08-20) Asselin, Jérémie; Picard-Lafond, Audrey; Boudreau, Denis; Fontaine, Nicolas
    The alteration of photophysical properties of fluorophores in the vicinity of a metallic nanostructure, a phenomenon termed plasmon- or metal-enhanced fluorescence (MEF), has been investigated extensively and used in a variety of proof-of-concept demonstrations over the years. A particularly active area of development in this regard has been the design of nanostructures where fluorophore and metallic core are held in a stable geometry that imparts improved luminosity and photostability to a plethora of organic fluorophores. This minireview presents an overview of MEF-based concentric core–shell sensors developed in the past few years. These architectures expand the range of applications of nanoparticles (NPs) beyond the uses possible with fluorescent molecules. Design aspects that are being described include the influence of the nanocomposite structure on MEF, notably the dependence of fluorescence intensity and lifetime on the distance to the plasmonic core. The chemical composition of nanocomposites as a design feature is also discussed, taking as an example the use of non-noble plasmonic metals such as indium as core materials to enhance multiple fluorophores throughout the UV-Vis range and tune the sensitivity of halide-sensing fluorophores operating on the principle of collisional quenching. Finally, the paper describes how various solid substrates can be functionalized with MEF-based nanosensors to bestow them with intense and photostable pH-sensitive properties for use in fields such as medical therapy and diagnostics, dentistry, biochemistry and microfluidics.
  • Publication
    Accès libre
    Indium@silica core–shell nanoparticles as plasmonic enhancers of molecular luminescence in the UV region
    (RCS, 2013-08-14) Boudreau, Denis; Magnan, François; Fontaine, Frédéric-Georges; Gagnon, Joanie
    Large fluorescence enhancement of UV-active molecular models Carbostyril 124 and tryptophan by core–shell indium-based plasmonic architectures demonstrates the metal's potential in the design of bioprobes. Precise control over the metal–fluorophore distance is achieved through the controlled deposition of a uniform silica layer over the nanosized indium particles
  • Publication
    Accès libre
    Enhancing galvanic replacement in plasmonic hollow nanoparticles : understanding the role of the speciation of metal ion precursors
    (Wiley, 2020-04-22) Boudreau, Denis; Richard-Daniel, Josée
    Hollow nanostructures offer great potential for plasmonic applications due to their strong and highly tunable localized surface plasmon resonance. The relationship between the plasmonic properties and geometry of hollow nanoparticles, such as core-shell size ratio, concentricity of the cavity and porosity of the wall, is well documented. Nanoscale galvanic replacement provides a simple, versatile and powerful route for the preparation of such hollow structures. Here we demonstrate how the efficiency of reductant-assisted galvanic replacement processes can be enhanced by controlling the degree of hydration and hydrolysis of the metal ion precursor using pH and pL as key control parameters (by analogy to pH, the letter p in the expression pL is used to indicate the decimal cologarithm associated with the concentration of the ligand L). Adjusting precursor speciation prior to the sacrificial template’s hollowing process offers a new strategy to tune the morphology and optical properties of plasmonic hollow nanostructures.