Faculté des arts et des sciences – Département de chimie – Travaux et publications

URI permanent de cette collectionhttps://hdl.handle.net/1866/19192

Cette collection accueille les publications savantes et d’autres types de travaux d’auteur.e.s associé.e.s à cette unité. Voir aussi la collection Thèses et mémoires de l'unité.

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Accès libre
Hydroxylamine umpolung in copper-catalyzed cross-coupling reactions to synthesize N-Arylhydroxylamine derivatives
Mathieu, Gary; Azek, Emna; Lai, Calvine; Lebel, Hélène; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American chemical society, 2024-03-13)
Hydroxylamine derivatives are well-established nitrogen precursors that undergo various transition metal-catalyzed transformations via the cleavage of the nitrogen–oxygen bond. Conversely, the development of a reagent containing a transferable electrophilic hydroxylamine has been elusive due to the inherent fragility of the N–O bond. Herein, we demonstrate the utility of hypervalent iodine chemistry to synthesize a reagent for the transfer of an electrophilic N–O moiety. Reagent 2 is a hydroxylamine umpolung that allows the formation of highly valuable N-arylhydroxylamine synthons via a copper-catalyzed cross-coupling reaction with boronic acids. The process with reagent 2 showed a wide functional group tolerance, especially with other electrophilic functional groups, and exhibited an orthogonal reactivity compared to other methods for synthesizing N-arylhydroxylamine derivatives. These can be subjected to Cope rearrangement and postfunctionalization, affording a variety of nitrogen-containing building blocks. Experimental and in silico mechanistic studies propose a catalytic cycle that involves the formation of a copper(II)-hydroxylamine species as the initial step. This species then reacts with boronic acid to produce the desired product.
Accès libre
Investigation of protic ionic liquid electrolytes for porous RuO2 micro-supercapacitors
Seenath, Jensheer Shamsudeen; Pech, David; Rochefort, Dominic; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Elsevier, 2022-09)
The rapid advancement of the Internet of things (IoT) with applications across various sectors urges the development of miniaturized energy-storage devices that can harvest or deliver energy with high power capabilities. While micro-supercapacitors can meet the high-power requirements of ubiquitous sensors connected to IoT networks, their low voltage and low energy density remain a major bottleneck preventing their wide-scale adoption. In this report, we develop micro-supercapacitors using RuO2 electrodes providing pseudocapacitive charge storage in protic ionic liquid-based non-aqueous electrolytes while enlarging their operational voltage. The triethylammonium bis(trifluoromethanesulfonyl)imide (TEAH-TFSI)-based interdigitated porous RuO2 micro-supercapacitors showed an extended cell voltage up to 2 V with 4 times more energy density compared with conventional H2SO4 electrolyte. We then developed an all-solid-state micro-supercapacitor using TEAH-TFSI-based ionogel electrolyte able to deliver high areal capacitance (79 mF cm−2 at 2 mV s−1) and long-term cycling stability that is superior to state-of-the-art ionogel-based micro-supercapacitors employing carbon-based or pseudocapacitive materials. This study gives a new perspective to develop all-solid-state micro-supercapacitors using pseudocapacitive active materials that can operate in ionic-liquid-based non-aqueous electrolytes compatible with on-chip IoT-based device applications seeking high areal energy/power performance.
Accès libre
Highly soluble viologen-PEG conjugates for aqueous organic redox flow batteries
Debiais, Alizée; Lai, Calvine; Boulanger, Thomas; Reynard, Guillaume; Hamlet, Louis; Généreux, Simon; Vaillancourt, Mick; Iftimie, Radu; Lebel, Hélène; Rochefort, Dominic; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American chemical society, 2024-12-17)
Aqueous organic redox flow batteries (AORFBs) are a promising solution for large-scale storage of renewable energy. These systems store electricity via electrochemically active organic molecules in an aqueous solvent, which offers superior safety and renewability compared with organic solvents. AORFBs provide a cost-effective alternative to aqueous vanadium-based redox flow batteries. The design of molecules with optimal electrochemical characteristics, solubility in water, and stability during extended cycling remains a significant challenge. In this study, the impact of PEGylation was investigated as a potential solution to address the aforementioned issues. Using a straightforward and effective synthetic methodology, a series of PEG-containing viologens with varying chain lengths, counterions, and symmetries were synthesized. Their physical and electrochemical properties, including solubility, viscosity, redox potential, and heterogeneous electron transfer rate constant, were studied. The results showed that PEG chains enhance solubility in water and that the chloride counterion increased solubility by 25% compared to the tosylate counterion. None of the studied modifications had a significant impact on the electrochemical properties, demonstrating the usefulness of N-substitution in tuning the solubility without compromising the use of the viologens as negolytes. Although asymmetric derivatives yielded higher solubilities (up to 2.7 M), the most stable organic negolyte under cycling conditions at a high concentration (1 M) was a symmetric viologen containing two PEG units (12 days with 0.29% capacity loss per day). The PEGylation of organic molecules proved to be a valuable approach to improving the aqueous solubility of electrolytes for use in aqueous organic redox flow batteries.
Accès libre
Surface-enhanced raman scattering nanoendoscope for quantification of a protein released under physiological stimulation in brain tissue
Hojjat Jodaylami, Maryam; Sanvi, Ohini Yanis; Rungta, Ravi; Kolta, Arlette; Masson, Jean-François; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2024-12-10)
A surface-enhanced Raman scattering (SERS) biosensor with minimal invasiveness and high spatial resolution has been developed as a nanoendoscope to detect changes in protein concentrations at specific sites in biological tissues. While generally applicable to various tissues or proteins, the SERS nanoendoscope is demonstrated for the quantitative detection of S100β, an astrocytic protein whose plasmatic levels are known to vary in several neuropathologies such as Alzheimer’s disease, schizophrenia, Down syndrome, Parkinson’s disease and epilepsy, but for which intratissular levels have not been locally monitored, demonstrating key attributes of the SERS nanoendoscope. The SERS nanoendoscope is fabricated with densely and well-dispersed deposited gold nanoparticles modified with anti-S100β primary antibody on pulled optical fibers with a tip diameter of 700 nm, conducive to noninvasive and regiospecific detection of the S100β protein in different regions of mouse brain slices under different physiological stimuli with micrometer resolution. Quantification was performed ex vivo using SERS-active nanotags with secondary antibodies with detection limits of 5 and 7 nM in phosphate-buffered saline solution and mouse brain slice, respectively. Various physiological stimuli were then applied ex vivo to wild-type and S100β-knockout mouse brain slices to demonstrate the SERS nanoendoscope under physiological conditions. The average concentration of S100β was increased to 27, 45, and 48 nM upon N-methyl-d-aspartate, electrical, and optogenetic stimulation, respectively, statistically higher than all controls, demonstrating the ability of the SERS nanoendoscope to quantify protein release in biological tissues.
Embargo
Organic ionic plastic crystal/PVDF composites prepared by solution casting
Wang, Yanyu; Rochefort, Dominic; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2024-09-24)
Solid-state electrolytes have been considered promising candidates to address the safety issues for next-generation lithium batteries. Organic ionic plastic crystals (OIPCs) are attracting increasing interest as solid electrolyte materials due to their unique advantages. In this study, an OIPC-based composite electrolyte consisting of the OIPC 1-ethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr12TFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and the polymer polyvinylidene fluoride (PVDF) has been developed by a facile solution casting strategy. Free-standing and flexible OIPC/polymer composite membranes were fabricated by the solution casting method, which not only provides flexibility and better electrode/electrolyte contact but also is compatible with current battery processing methods. The thermal behavior and ionic conductivity of the OIPC-based composites with different molar proportions (10 mol % to 67 mol %) of LiTFSI in LiTFSI/Pyr12TFSI, as well as different weight fractions (20 wt % to 50 wt %) of PVDF, were studied to understand the effect on transport properties. Among all the compositions studied, the Li0.33[Pyr12]0.67TFSI/30 wt % PVDF composite exhibited high ionic conductivity (e.g., 1.2 × 10–4 S cm–1 at 30 °C). The Li0.33[Pyr12]0.67TFSI/30 wt % PVDF composite membrane was evaluated in a Li/Li symmetric cell and was cycled stably over 900 h at a current density of 0.1 mA cm–2 at 50 °C, demonstrating that this OIPC/polymer composite electrolyte enabled the reversible and stable lithium plating and stripping behaviors. Further tests of the Li0.33[Pyr12]0.67TFSI/30 wt % PVDF composite membrane as a solid electrolyte in a LiFePO4/Li cell presented a high specific discharge capacity of 149 mAh g–1 at 0.1 C and a long cycle life of over 440 cycles with a capacity retention of 89% at 0.5 C at 50 °C, which showed improved rate capability and cycling stability in comparison with the composites with similar compositions but obtained by the powder pressing method. This study demonstrated the potential of the OIPC/polymer composite solid electrolyte prepared by the solution casting method and will promote the development of high-performance OIPC-based composite electrolytes for solid-state batteries.
Accès libre
Anisotropic contributions in the chromatographic elution behavior of fullerenes and fullertubes
Bourret, Emmanuel; Stevenson, Steven; Côté, Michel; Université de Montréal. Faculté des arts et des sciences. Département de physique (American Chemical Society, 2024-07-24)
The retention behavior of fullerenes and fullertubes on a PYE column in reversed-phase chromatography was investigated to clarify the influence of their shapes on the separation process. The impact of anisotropy was further elucidated using a pair potential interaction model, together with experimental data and ab initio calculations, to evaluate its contribution to various parameters characterizing the interaction models. The findings indicate that the shape of fullerenes plays a more significant role than anticipated in the retention mechanisms, highlighting the necessity of considering the shape of fullerenes and fullertubes to accurately predict their retention times. Furthermore, a phenomenological pair potential was devised to demonstrate the feasibility of precisely predicting the retention times of fullerenes and fullertubes through first-principles calculations, regardless of their shape. The existence of such a model paves the way for the development of a method to identify isomers of fullerenes from minute amounts of sample.
Embargo
Electrospun materials with high reflectance and polarization contrast for sensing applications in the mid-infrared atmospheric window
Laramée, Arnaud; Roy, Olivier; Pellerin, Christian; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2024-06-06)
Several applications in remote sensing and thermal management require materials with high reflectivity and polarization contrast in the mid-infrared (MIR) spectral range. However, the existing options often fall short in terms of mechanical properties and practicality, especially for field deployment. To address this challenge, we leverage the polaritonic response of poly(oxymethylene) (POM) and the anisotropy induced by electrospinning to produce robust POM fiber mats with high reflectance and polarization contrast in the MIR atmospheric window. Specular reflection IR spectroscopy demonstrates that the optical properties can be optimized by a series of mat post-treatments, namely submersion with a nonsolvent, incorporation of an index-matching medium, drawing, and compression, which were applied iteratively to refine the optical response. The optimized mats achieve a maximum reflectance of 60 ± 8% and a corresponding polarization contrast (degree of linear polarization) of 0.52 ± 0.01. Importantly, the formulated materials remain flexible and generally retain appropriate optical properties under long-term storage and when exposed to harsh simulated operational conditions. As a result, they are considered promising target substrates for the development, testing, and field deployment of advanced MIR polarimetric remote sensors.
Embargo
Engineered robust hydrophobic/hydrophilic nanofibrous scaffolds with drug-eluting, antioxidant, and antimicrobial capacity
Soleimani, Foad; Pellerin, Christian; Omidfar, Kobra; Bagheri, Reza; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2024-05-22)
Multifunctional nanofibrous architectures have attracted extensive attention for biomedical applications due to their adjustable and versatile properties. Electrospun fabrics stand out as key building blocks for these structures, yet improving their mechanobiological and physicochemical performance is a challenge. Here, we introduce biodegradable engineered hydrophobic/hydrophilic scaffolds consisting of electrospun polylactide nanofibers coated with drug-eluting synthetic (poly(vinyl alcohol)) and natural (starch) polymers. The microstructure of these composite scaffolds was tailored for an increased hydrophilicity, optimized permeability, water retention capacity of up to 5.1 g/g, and enhanced mechanical properties under both dry and wet conditions. Regarding the latter, normalized tensile strengths of up to 32.4 MPa were achieved thanks to the improved fiber interactions and fiber-coating stress transfer. Curcumin was employed as a model drug, and its sustained release in a pure aqueous medium was investigated for 35 days. An in-depth study of the release kinetics revealed the outstanding water solubility and bioavailability of curcumin, owing to its complexation with the hydrophilic polymers and further delineated the role of the hydrophobic nanofibrous network in regulating its release rate. The modified curcumin endowed the composites with antioxidant activities up to 5.7 times higher than that of free curcumin as well as promising anti-inflammatory and bacteriostatic activities. The cytocompatibility and cell proliferation capability on human dermal fibroblasts also evidenced the safe use of the constructs. Finally, the fabrics present pH-responsive color-changing behavior easily distinguishable within the pH range of 5–9. Thus, these designs offer a facile and cost-effective roadmap for the fabrication of smart multifunctional biomaterials, especially for chronic wound healing.
Embargo
Heterogeneous electron transfer of ferrocene in acetonitrile-LiTFSI highly concentrated electrolyte
Généreux, Simon; Dionne, Éric R.; Rochefort, Dominic; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Elsevier, 2023-11-07)
Highly concentrated electrolytes (HCE) are mixtures of equivalent or near-equivalent amounts of salt and solvent displaying a liquid phase at room temperature. HCE have intensively studied for application in energy storage devices with a particular focus on batteries since the demonstration of the lack of reactivity of lithium metal in an acetonitrile HCE. The lack of "free" solvent molecules in HCE is responsible for their stability. This feature also suggests that heterogeneous electron transfer (ET) in HCE could be different from conventional electrolytes because of the importance of solvent reorganization during ET. Thus, we investigated the heterogeneous electron transfer of the ferrocenium/ferrocene (Fc+/Fc) redox couple as a function of concentration of the salt Li bis(trifluoromethanesulfonyl)imide in acetonitrile, a model system for HCE. We show that while the diffusivity of Fc (Shoup-Szabo) follows the trend with viscosity (η) expected from the Stokes-Einstein relation over the entire concentration range, the ET rate constant (k0) variation with η on the other hand diverges from ideality. Using Raman spectroscopy in the solution and on the surface (EC-SERS), we show that the most likely cause for the difference in ET rate constant between dilute and highly concentrated electrolytes involves a strong coordination of the ferrocenium with the complexes found in HCE. This new knowledge highlights the importance of increasing fundamental research on the topic of electrochemistry in HCE.
Accès libre
Groupe de recherche Reber : Département de chimie, Université de Montréal
Reber, Christian; Université de Montréal. Faculté des arts et des sciences. Département de chimie (2024-03)
Accès libre
Colossal C130 fullertubes : soluble [5,5] C130-D5h(1) pristine molecules with 70 nanotube carbons and two 30-atom hemifullerene end-caps
Bourret, Emmanuel; Liu, Xiaoyang; Noble, Cora A.; Cover, Kevin; Davidson, Tanisha P.; Huang, Rong; Koenig, Ryan M.; Reeves, K. Shawn; Vlassiouk, Ivan V.; Côté, Michel; Baxter, Jefferey S.; Lupini, Andrew R.; Geohegan, David B.; Dorn, Harry C.; Stevenson, Steven; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2023-10-27)
We report the seminal experimental isolation and DFT characterization of pristine [5,5] C130-D5h(1) fullertubes. This achievement represents the largest soluble carbon molecule obtained in its pristine form. The [5,5] C130 species is the highest aspect ratio fullertube purified to date and now surpasses the recent gigantic [5,5] C120-D5d(1). In contrast to C90, C100, and C120 fullertubes, the longer C130-D5h has more nanotubular carbons (70) than end-cap fullerenyl atoms (60). Starting from 39,393 possible C130 isolated pentagon rule (IPR) structures and after analyzing polarizability, retention time, and UV–vis spectra, these three layers of data remarkably predict a single candidate isomer and fullertube, [5,5] C130-D5h(1). This structural assignment is augmented by atomic resolution STEM data showing distinctive and tubular “pill-like” structures with diameters and aspect ratios consistent with [5,5] C130-D5h(1) fullertubes. The high selectivity of the aminopropanol reaction with spheroidal fullerenes permits facile separation and removal of fullertubes from soot extracts. Experimental analyses (HPLC retention time, UV–vis, and STEM) were synergistically used (with polarizability and DFT property calculations) to down select and confirm the C130 fullertube structure. Achieving the isolation of a new [5,5] C130-D5h fullertube opens the door to application development and fundamental studies of electron confinement, fluorescence, and metallic character for a fullertube series of molecules with systematic tubular elongation. This [5,5] fullertube family also invites comparative studies with single-walled carbon nanotubes (SWCNTs), nanohorns (SWCNHs), and fullerenes.
Accès libre
Stable amide activation of N-acetylated glycosamines for the synthesis of fused polycyclic glycomimetics
Zarei, Samaneh; Motard, Mélina; Cecioni, Samy; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2024-01-02)
N-Acetylation of carbohydrates is an underexplored target for chemoselective derivatization and generation of glycomimetic scaffolds. Through mild amide activation, we report that N-acetimidoyl heterocycles are stable in neutral or basic conditions yet are excellent leaving groups through acid catalysis. While this specific reactivity could prove broadly useful in amide activation strategies, stably activated N-acetylated sugars can also be diversified using libraries of hydrazides. We optimized an acid-catalyzed one-pot sequence that includes nucleophilic displacement, cyclodehydration, and intramolecular glycosylation to ultimately deliver pyranosides fused to morpholines or piperazines. This strategy of stable activation followed by acid-triggered reaction sequences exemplifies the efficient assembly of 3D-rich fused glycomimetic libraries.
Accès libre
Molecular-level photo-orientation insights into macroscopic photo-induced motion in azobenzene-containing polymer complexes
Kamaliardakani, Mahnaz; Vapaavuori, Jaana; Xiaoxiao, Wang; Sabat, Ribal Georges; Bazuin, C. Geraldine; Pellerin, Christian; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2021-07-13)
As part of continuing efforts to deepen the understanding of photo-induced mass transport in azo-containing polymers, we compared the diffraction efficiency (DE) during surface-relief grating (SRG) inscription, photo-induced molecular orientation (), and thermal stability in two sets of supramolecular azopolymer complexes, namely, hydrogen-bonded (H-bonded) and ionically bonded (i-bonded) complexes, both as a function of the polymer degree of polymerization (DP). To that end, poly(4-vinylpyridine) (P4VP) polymers with DPs of 41, 480, and 1900 were H-bonded at an equimolar ratio with 4-hydroxy-4′-dimethylaminoazobenzene (azoOH), and the fully quaternized derivatives of the three P4VPs (P4VPMe) were i-bonded via ion exchange to sodium 4-[(4-dimethylamino)-phenylazo]benzene sulfonate (azoSO3), also known as methyl orange, where the OH functionality of azoOH is replaced by a sulfonate group. The i-bonded complexes show much better DE performances and levels than those of H-bonded complexes, which we relate to the liquid crystal structure of the former complexes. Fitting the curves by a biexponential equation leads to two parameters associated with a fast trans–cis or angular hole burning (AHB) process and a slow angular redistribution (AR) process of the azo, respectively. It is found that AHB is predominant in the H-bonded complexes, whereas the AR contribution is much greater in the i-bonded complexes, assuring their superior SRG efficiency that is enabled by the anisotropic free volume created mainly by the AR process. In each set of complexes, the SRG efficiency is much better for the lowest DP complex, while the AR contribution is constant (and low) for the H-bonded complexes and increases roughly linearly with the decrease in DP for the i-bonded complexes. The latter difference might be related to the presence of entanglements in the complexes with DPs 480 and 1900, which slow down the macroscopic movement during SRG inscription but not the molecular-scale movement in photo-orientation.
Accès libre
Target and nontarget screening of PFAS in drinking water for a large-scale survey of urban and rural communities in Québec, Canada
Munoz, Gabriel; Liu, Min; Duy, Sung Vo; Liu, Jinxia; Sauvé, Sébastien; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Elsevier, 2023-02-16)
Limited monitoring data are available regarding the occurrence of emerging per- and polyfluoroalkyl substances (PFAS) in drinking water. Here, we validated an analytical procedure for 42 PFAS with individual detection limits of 0.001–0.082 ng/L. We also evaluated how different sample pH conditions, dechlorinating agents, and storage holding times might affect method performance. PFAS were analyzed in tap water samples collected at a large spatial scale in Quebec, Canada, covering 376 municipalities within 17 administrative regions. Target and nontarget screening revealed the presence of 31 and 23 compounds, respectively, representing 24 homolog classes. Overall, 99.3% of the tap water samples were positive for at least one PFAS, and the ƩPFAS ranged from below detection limits to 108 ng/L (95th percentile: 13 ng/L). On average, ƩPFAS was 12 times higher in tap water produced from surface water than groundwater; however, 6 of the top 10 contaminated locations were groundwater-based. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) had high detection rates (88% and 80%, respectively). PFOS (median: 0.15 ng/L; max: 13 ng/L) and PFOA (median: 0.27 ng/L; max: 8.1 ng/L) remained much lower than current Health Canada guidelines but higher than USEPA's interim updated health advisories. Short-chain (C3-C6) perfluoroalkyl sulfonamides were also recurrent, especially the C4 homolog (FBSA: detection rate of 50%). The 6:2 fluorotelomer sulfonyl propanoamido dimethyl ethyl sulfonate (6:2 FTSO2PrAd-DiMeEtS) was locally detected at ∼15 ng/L and recurred in 8% of our samples. Multiple PFAS that are most likely to originate from aqueous film-forming foams were also reported for the first time in tap water, including X:3 and X:1:2 fluorotelomer betaines, hydroxylated X:2 fluorotelomer sulfonates, N-trimethylammoniopropyl perfluoroalkane sulfonamides (TAmPr-FHxSA and TAmPr-FOSA), and N-sulfopropyl dimethylammoniopropyl perfluoroalkane sulfonamidopropyl sulfonates (N-SPAmP-FPeSAPS and N-SPAmP-FHxSAPS).
Accès libre
Metal-ligand bonding in six-coordinate d-block complexes probed by luminescence spectroscopy at variable pressure
Reber, Christian; Dab, Chahinez; Blanc, Pierre-François; Université de Montréal. Faculté des arts et des sciences. Département de chimie (De Gruyter, 2022)
Luminescence spectra measured at variable pressure can reveal unique insight on ground- and emitting state properties of transition metal compounds. This chapter summarizes illustrative results for chromium(III) complexes with the d3 electron configuration and oxo complexes of rhenium(V) and molybdenum(IV) with the d2 configuration. Their luminescence transitions only involve electronic configuration changes within the t2 (O point group) molecular orbitals, leading to narrow spin-flip bands and broad bands with vibronic structure for the chromium(III) and metal-oxo complexes, respectively.
Accès libre
Mixtures of rare earth elements show antagonistic interactions in Chlamydomonas reinhardtii
Morel, Elise; Cui, Lei; Zerges, William; Wilkinson, Kevin James; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Elsevier, 2021-06-14)
In order to better understand the environmental risks of the rare earth elements (REEs), it is necessary to determine their fate and biological effects under environmentally relevant conditions (e.g. at low concentrations, REE mixtures). Here, the unicellular freshwater microalga, Chlamydomonas reinhardtii, was exposed for 2 h to one of three soluble REEs (Ce, Tm, Y) salts at 0.5 μM or to an equimolar mixture of these REEs. RNA sequencing revealed common biological effects among the REEs. Known functions of the differentially expressed genes support effects of REEs on protein processing in the endoplasmic reticulum, phosphate transport and the ho- meostasis of Fe and Ca. The only stress response detected was related to protein misfolding in the endoplasmic reticulum. When the REEs were applied as a mixture, antagonistic effects were overwhelmingly observed with transcriptomic results suggesting that the REEs were initially competing with each other for bio-uptake. Metal biouptake results were consistent with this interpretation. These results suggest that the approach of government agencies to regulate the REEs using biological effects data from single metal exposures may be a largely con- servative approach.
Accès libre
Thermal degradation of conventional and nanoencapsulated azoxystrobin due to processing in water, spiked strawberry and incurred strawberry models
Wang, Peiying; Gravel, Valérie; Bueno, Vinicius; Galhardi, Juliana A.; Ghoshal, Subhasis; Wilkinson, Kevin James; Bayen, Stéphane; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2022-09-21)
Nanoencapsulated formulations of pesticides have been recently developed, and some products are now marketed for specific applications in agriculture. Pesticide residues present in raw agricultural products can degrade or react during food processing steps. To date, the fate of nanopesticides during food processing has not been well described. In this study, the thermal degradation of azoxystrobin (AZOX) in conventional and nanoencapsulated (Allosperse and nSiO2) formulations was first assessed in water, spiked strawberry, and incurred strawberry models. The thermal degradation followed first-order kinetics when heated at 100 °C in the water model. The thermal degradation of AZOX in nanoformulations in strawberry models (18% AZOX decrease) was comparable to or lower than in the conventional formulation (21%), possibly due to the nanocarriers protecting the active ingredient from hydrolytic degradation. Out of 32 thermal degradation products (TDPs), only two were detected in both the spiked water and strawberry models, indicating differences in the thermal degradation reactions for AZOX in these two models. Identical TDPs were detected for both conventional and nanoformulations for each specific model, except for the absence of one (TDP22) in the nSiO2 formulations. The nanoencapsulation of AZOX did not result in new TDPs in any of the matrices. Only six of the TDPs detected in water, four in spiked strawberries, and two in incurred strawberries have been previously reported in environmental studies on the metabolism of AZOX. Based on the observed TDPs, AZOX thermal degradation pathways include ether cleavage, hydrolysis, demethylation, and decarboxylation. Overall, although nanocarriers have no impact on the degradation product types, nanocarriers had a slight but significant impact on the degradation rate of pesticide active ingredients.
Accès libre
Field evaluation of the potential effects of polymer and silica-based nanopesticides on strawberries and agricultural soils
Galhardi, Juliana A.; Wang, Peiying; Bueno, Vinicius; Ghoshal, Subhasis; Gravel, Valérie; Wilkinson, Kevin James; Bayen, Stéphane; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Royal Society of Chemistry, 2022-08-18)
Polymeric and SiO2 nanoparticles can be used as nanocarriers to improve the efficacy of pesticide delivery in agriculture. However, the environmental fate and potential risks of this type of nanopesticides in agroecosystems remain poorly understood. In this study, two separate active ingredients, azoxystrobin (AZOX) and bifenthrin (BFT), loaded into two different types of nanocarriers (Allosperse® polymeric nanoparticles and SiO2 nanoparticles), were applied to strawberry plants under realistic field conditions over two growing seasons. The pesticide concentration profiles in soil and plant tissues, plant growth and soil microorganisms were compared among treatments. Although the encapsulation appeared to reduce retention of the active ingredients (AI) to the soils, few of the sensitive indicators of ecosystem health showed any differences when compared to controls. Bioaccumulation of the AI by the strawberry plants and fruit was similar for classical and nano-applications of the AI. No significant differences were observed among the conventional, nanopesticide or control treatments in terms of fruit mass, number of flowers and leaves, or biomass. None of the pesticide formulations appeared to systematically affect soil enzyme activity. Finally, the soil microbial composition (Shannon indices, Principal Coordinate Analysis plots) and function (soil enzyme activity) only showed some transient, initial effects due to the pesticides, but did not distinguish among formulations
Accès libre
Development of an LC-MS-based method to study the fate of nanoencapsulated pesticides in soils and strawberry plant
Wang, Peiying; Galhardi, Juliana A.; Liu, Lan; Bueno, Vinicius; Ghosha, Subhasis; Gravel, Valérie; Wilkinson, Kevin James; Bayen, Stéphane; Université de Montréal. Faculté des arts et des sciences. Département de chimie (Elsevier, 2021-12-04)
The increased production and use of nanopesticides will increase the likelihood of their exposure to humans and the environment. In order to properly evaluate their risk, it will be necessary to rigorously quantify their concentrations in major environmental compartments including water, soil and food. Due to major differences in the characteristics of their formulation, it is unclear whether analytical techniques that have been developed for conventional pesticides will allow quantification of the nano-forms. Therefore, it is necessary to develop and validate analytical techniques for the quantification of nanopesticides in foods and the environment. The goal of this study was to validate a method for analyzing the active ingredients of two pesticides with different physicochemical properties: azoxystrobin (AZOX, a fungicide, log Kow 3.7) and bifenthrin (BFT, an insecticide, log Kow 6.6) that were applied to agricultural soils, either as a conventional formulation or encapsulated in nanoparticles (either Allosperse® or porous hollow nSiO2). Pesticide-free strawberry plants (Fragaria × ananassa) and three different agricultural soils were spiked with the active ingredients (azoxystrobin and bifenthrin), in either conventional or nano formulations. A modified QuEChERS approach was used to extract the pesticides from the strawberry plants (roots, leaves and fruits) and a solvent extraction (1:2 acetonitrile) was employed for the soils. Samples were analyzed by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry in order to determine method detection limits, recoveries, precision and matrix effects for both the “conventional” and nanoencapsulated pesticides. Results for the modified method indicated good recoveries and precision for the analysis of the nanoencapsulated pesticides from strawberries and agricultural soils, with recoveries ranging from 85 to 127% (AZOX) and 68–138% (BFT). The results indicated that the presence of the nanoencapsulants had significant effects on the efficiency of extraction and the quantification of the active ingredients. The modified analytical methods were successfully used to measure strawberry and soil samples from a field experiment, providing the means to explore the fate of nanoencapsulated pesticides in food and environmental matrices.
Accès libre
Detection and characterization of ZnO nanoparticles in surface and waste waters using single particle ICPMS
Hadioui, Madjid; Merdzan, Vladimir; Wilkinson, Kevin James; Université de Montréal. Faculté des arts et des sciences. Département de chimie (American Chemical Society, 2015-04-29)
The increasing production of ZnO nanoparticles (nZnO) makes their analysis and characterization extremely important from an ecological risk perspective, especially at the low concentrations at which they are expected to be found in natural waters. Single particle ICPMS (SP-ICPMS) is one of the few techniques available to detect and characterize nanoparticles at environmentally relevant concentrations. Unfortunately, at the very low particle concentrations where SP-ICPMS is performed, significant dissolution of the nZnO generally increases background levels of dissolved Zn to the point where measurements are not generally possible. By hyphenating SP-ICPMS with an ion-exchange resin, it was possible to characterize and quantify nZnO in order to gain insight into the nature of the nZnO in natural waters. Spiked and unspiked water samples were analyzed using a SP-ICPMS that was coupled to a column containing a strong metal binding resin (Chelex 100). In addition to the detection of ZnO nanoparticles and the determination of a size distribution in natural waters, it was possible to partition the dissolved Zn among free and/or labile and strongly bound Zn fractions. In two natural waters, a high proportion (ca. 93–100%) of dissolved Zn was measured, and the residual ZnO particles were mainly composed of small agglomerates (average sizes ranging from 133.6 to 172.4 nm in the surface water and from 167.6 to 216.4 nm in the wastewater effluent). Small numbers of small nanoparticles were also detected in nonspiked waters.

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