160 results on '"Tufenkji N"'
Search Results
2. Unraveling the toxicity of tire wear contamination in three freshwater species: From chemical mixture to nanoparticles
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Roubeau Dumont, E., Gao, X., Zheng, J., Macairan, J., Hernandez, L.M., Baesu, A., Bayen, S., Robinson, S.A., Ghoshal, S., and Tufenkji, N.
- Published
- 2023
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3. From freshwaters to bivalves: Microplastic distribution along the Saint-Lawrence river-to-sea continuum
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Rowenczyk, L., Cai, H., Nguyen, B., Sirois, M., Côté-Laurin, M.-C., Toupoint, N., Ismail, A., and Tufenkji, N.
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- 2022
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4. Optimal preparation and purification of PRD1-like bacteriophages for use in environmental fate and transport studies
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Mesquita, M.M.F., Stimson, J., Chae, G.-T., Tufenkji, N., Ptacek, C.J., Blowes, D.W., and Emelko, M.B.
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- 2010
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5. Fate and Transport of Microbial Contaminants in Groundwater
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Tufenkji, N., primary and Emelko, M.B., additional
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- 2011
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6. Effect of fluoropolymer-based culture vessel surface on monocyte differentiation
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Fekete, N., primary, Sabbatier, G., additional, Wargenau, A., additional, Béland, A., additional, Xu, S., additional, Tufenkji, N., additional, and Hoesli, C.A., additional
- Published
- 2018
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7. QCM-D and NanoTweezer measurements to characterize the effect of soil cellulase on the deposition of PEG-coated TiO2nanoparticles in model subsurface environments
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Akanbi, M. O., primary, Hernandez, L. M., additional, Mobarok, M. H., additional, Veinot, J. G. C., additional, and Tufenkji, N., additional
- Published
- 2018
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8. Green Technology: Tannin-Based Corrosion Inhibitor for Protection of Mild Steel
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Dargahi, M., primary, Olsson, A.L.J., additional, Tufenkji, N., additional, and Gaudreault, R., additional
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- 2015
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9. 325 - Effect of fluoropolymer-based culture vessel surface on monocyte differentiation
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Fekete, N., Sabbatier, G., Wargenau, A., Béland, A., Xu, S., Tufenkji, N., and Hoesli, C.A.
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- 2018
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10. QCM-D and NanoTweezer measurements to characterize the effect of soil cellulase on the deposition of PEG-coated TiO2 nanoparticles in model subsurface environments.
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Akanbi, M. O., Hernandez, L. M., Mobarok, M. H., Veinot, J. G. C., and Tufenkji, N.
- Published
- 2018
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11. Towards understanding the mechanisms and the kinetics of nanoparticle penetration through protective gloves
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Vinches, L, primary, Peyrot, C, additional, Lemarchand, L, additional, Boutrigue, N, additional, Zemzem, M, additional, Wilkinson, K J, additional, Hallé, S, additional, and Tufenkji, N, additional
- Published
- 2015
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12. The road to nowhere: equilibrium partition coefficients for nanoparticles
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Praetorius, A., Tufenkji, N., Goss, Kai Uwe, Scheringer, M., von der Kammer, F., Elimelech, M., Praetorius, A., Tufenkji, N., Goss, Kai Uwe, Scheringer, M., von der Kammer, F., and Elimelech, M.
- Abstract
Adequate fate descriptors are crucial input parameters in models used to predict the behaviour andtransport of a contaminant in the environment and determine predicted environmental concentrationsfor risk assessment. When new fate models are being developed for emerging contaminants, such asengineered nanoparticles (ENPs), special care has to be applied in adjusting conventional approachesand fate descriptors to a new set of substances. The aim of this paper is to clarify misconceptions aboutthe applicability of equilibrium partition coefficients, such as the octanol–water partition coefficient (Kow)or the soil–water distribution coefficient (Kd), whose application in the context of ENP fate assessment isfrequently suggested despite lacking scientific justification. ENPs are present in the environment asthermodynamically unstable suspensions and their behaviour must be represented by kineticallycontrolled attachment and deposition processes as has been established by colloid science. Here, weillustrate the underlying theories of equilibrium partitioning and kinetically controlled attachment anddiscuss why the use of any coefficient based on equilibrium partitioning is inadequate for ENPs and canlead to significant errors in ENP fate predictions and risk assessment.
- Published
- 2014
13. Kinetic analysis of attached growth nitrification in cold climates
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Delatolla, R., primary, Tufenkji, N., primary, Comeau, Y., primary, Gadbois, A., primary, Lamarre, D., primary, and Berk, D., primary
- Published
- 2009
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14. Breakdown of Colloid Filtration Theory: Role of the Secondary Energy Minimum and Surface Charge Heterogeneities
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Tufenkji, N. and Elimelech, M.
- Abstract
The mechanisms and causes of deviation from the classical colloid filtration theory (CFT) in the presence of repulsive Derjaguin−Landau−Verwey−Overbeek (DLVO) interactions were investigated. The deposition behavior of uniform polystyrene latex colloids in columns packed with spherical soda-lime glass beads was systematically examined over a broad range of physicochemical conditions, whereby both the fluid-phase effluent particle concentration and the profile of retained particles were measured. Experiments conducted with three different-sized particles in a simple (1:1) electrolyte solution reveal the controlling influence of secondary minimum deposition on the deviation from CFT. In a second series of experiments, sodium dodecyl sulfate (SDS) was added to the background electrolyte solution with the intent of masking near-neutrally charged regions of particle and collector surfaces. These results indicate that the addition of a small amount of anionic surfactant is sufficient to reduce the influence of certain surface charge inhomogeneities on the deviation from CFT. To verify the validity of CFT in the absence of surface charge heterogeneities, a third set of experiments was conducted using solutions of high pH to mask the influence of metal oxide impurities on glass bead surfaces. The results demonstrate that both secondary minimum deposition and surface charge heterogeneities contribute significantly to the deviation from CFT generally observed in colloid deposition studies. It is further shown that agreement with CFT is obtained even in the presence of an energy barrier (i.e., repulsive colloidal interactions), suggesting that it is not the general existence of repulsive conditions which causes deviation but rather the combined occurrence of fast and slow particle deposition.
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- 2005
15. Deviation from the Classical Colloid Filtration Theory in the Presence of Repulsive DLVO Interactions
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Tufenkji, N. and Elimelech, M.
- Abstract
A growing body of experimental evidence suggests that the deposition behavior of microbial particles (e.g., bacteria and viruses) is inconsistent with the classical colloid filtration theory (CFT). Well-controlled laboratory-scale column deposition experiments were conducted with uniform model particles and collectors to obtain insight into the mechanisms that give rise to the diverging deposition behavior of microorganisms. Both the fluid-phase effluent particle concentration and the profile of retained particles were systematically measured over a broad range of physicochemical conditions. The results indicate that, in the presence of repulsive Derjaguin−Landau−Verwey−Overbeek (DLVO) interactions, the concurrent existence of both favorable and unfavorable colloidal interactions causes significant deviation from the CFT. A dual deposition mode model is presented which considers the combined influence of fast and slow particle deposition. This model is shown to adequately describe both the spatial distribution of particles in the packed bed and the suspended particle concentration at the column effluent.
- Published
- 2004
16. Reply to Comment on Breakdown of Colloid Filtration Theory: Role of the Secondary Energy Minimum and Surface Charge Heterogeneities
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Tufenkji, N. and Elimelech, M.
- Published
- 2005
17. Demonstrating scale-up of a novel water treatment process using super-bridging agents.
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Blancho F, Lapointe M, Quevedo AC, Kannan K, and Tufenkji N
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- Sewage, Polymers chemistry, Flocculation, Cellulose, Waste Disposal, Fluid methods, Water Purification methods
- Abstract
Fiber-based materials have emerged as a promising option to increase the efficiency of water treatment plants while reducing their environmental impacts, notably by reducing the use of unsustainable chemicals and the size of the settling tank. Cellulose fiber-based super-bridging agents are sustainable, reusable, and versatile materials that considerably improve floc separation in conventional settling tanks or via alternative screening separation methods. In this study, the effectiveness of fiber-based materials for wastewater treatment was evaluated at lab-scale (0.25 L) and at pilot-scale (20 L) for two separation methods, namely settling and screening. For the fiber-based method, the performance of floc separation during settling was slightly affected by an 80x upscaling factor. A small decrease in turbidity removal from 93 and 86 % was observed for the jar and pilot tests, respectively. By contrast, the turbidity removal of the conventional treatment, i.e., no fibers with a settling separation, was largely affected by the upscaling with turbidity removals of 84 and 49 % for jar and pilot tests, respectively. Therefore, results are suggesting that fiber-based super-bridging agents could be implemented in full-scale water treatment plants. Moreover, the tested fibers increase the robustness of treatment by providing better floc removal than conventional treatment under several challenging conditions such as low settling time and screening with coarse screen mesh size. Furthermore, at both lab-scale and pilot-scale, the use of fiber-based materials reduced the demand for coagulant and flocculant, potentially lowering the operational costs of water treatment plants and reducing the accumulation of metal-based coagulants and synthetic polymers in sludge. Acute toxicity tests using the model organism Daphnia magna show that the cellulose fibers introduce insignificant toxicity at the optimized fiber concentration. Although dedicated mechanistic studies are required at various scales to understand in detail the influence of fibers on water treatment (coagulation/flocculation time, floc formation, floc size distribution velocity gradient, etc.), the efficacy and scalability of the fiber-based approach, along with its minimal environmental impact, position it as a viable and sustainable option for existing and future wastewater treatment plants., Competing Interests: Declaration of competing interest M. Lapointe and N. Tufenkji have applied for a patent on the use of fiber-based materials for water treatment., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
- Published
- 2024
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18. Effects of Surface Topography and Cellular Biomechanics on Nanopillar-Induced Bactericidal Activity.
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Valiei A, Bryche JF, Canva M, Charette PG, Moraes C, Hill RJ, and Tufenkji N
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- Biomechanical Phenomena, Bacteria, Cell Wall, Nanostructures chemistry
- Abstract
Bacteria are mechanically resistant biological structures that can sustain physical stress. Experimental data, however, have shown that high-aspect-ratio nanopillars deform bacterial cells upon contact. If the deformation is sufficiently large, it lyses the bacterial cell wall, ultimately leading to cell death. This has prompted a novel strategy, known as mechano-bactericide technology, to fabricate antibacterial surfaces. Although adhesion forces were originally proposed as the driving force for mechano-bactericidal action, it has been recently shown that external forces, such as capillary forces arising from an air-water interface at bacterial surfaces, produce sufficient loads to rapidly kill bacteria on nanopillars. This discovery highlights the need to theoretically examine how bacteria respond to external loads and to ascertain the key factors. In this study, we developed a finite element model approximating bacteria as elastic shells filled with cytoplasmic fluid brought into contact with an individual nanopillar or nanopillar array. This model elucidates that bacterial killing caused by external forces on nanopillars is influenced by surface topography and cell biomechanical variables, including the density and arrangement of nanopillars, in addition to the cell wall thickness and elastic modulus. Considering that surface topography is an important design parameter, we performed experiments using nanopillar arrays with precisely controlled nanopillar diameters and spacing. Consistent with model predictions, these demonstrate that nanopillars with a larger spacing increase bacterial susceptibility to mechanical puncture. The results provide salient insights into mechano-bactericidal activity and identify key design parameters for implementing this technology.
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- 2024
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19. Exposure protocol for ecotoxicity testing of microplastics and nanoplastics.
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Abdolahpur Monikh F, Baun A, Hartmann NB, Kortet R, Akkanen J, Lee JS, Shi H, Lahive E, Uurasjärvi E, Tufenkji N, Altmann K, Wiesner Y, Grossart HP, Peijnenburg W, and Kukkonen JVK
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- Humans, Plastics toxicity, Microplastics analysis, Microplastics toxicity, Water Pollutants, Chemical analysis, Water Pollutants, Chemical chemistry, Water Pollutants, Chemical toxicity
- Abstract
Despite the increasing concern about the harmful effects of micro- and nanoplastics (MNPs), there are no harmonized guidelines or protocols yet available for MNP ecotoxicity testing. Current ecotoxicity studies often use commercial spherical particles as models for MNPs, but in nature, MNPs occur in variable shapes, sizes and chemical compositions. Moreover, protocols developed for chemicals that dissolve or form stable dispersions are currently used for assessing the ecotoxicity of MNPs. Plastic particles, however, do not dissolve and also show dynamic behavior in the exposure medium, depending on, for example, MNP physicochemical properties and the medium's conditions such as pH and ionic strength. Here we describe an exposure protocol that considers the particle-specific properties of MNPs and their dynamic behavior in exposure systems. Procedure 1 describes the top-down production of more realistic MNPs as representative of MNPs in nature and particle characterization (e.g., using thermal extraction desorption-gas chromatography/mass spectrometry). Then, we describe exposure system development for short- and long-term toxicity tests for soil (Procedure 2) and aquatic (Procedure 3) organisms. Procedures 2 and 3 explain how to modify existing ecotoxicity guidelines for chemicals to target testing MNPs in selected exposure systems. We show some examples that were used to develop the protocol to test, for example, MNP toxicity in marine rotifers, freshwater mussels, daphnids and earthworms. The present protocol takes between 24 h and 2 months, depending on the test of interest and can be applied by students, academics, environmental risk assessors and industries., (© 2023. Springer Nature Limited.)
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- 2023
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20. Effects of weathering on the properties and fate of secondary microplastics from a polystyrene single-use cup.
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Alimi OS, Claveau-Mallet D, Lapointe M, Biu T, Liu L, Hernandez LM, Bayen S, and Tufenkji N
- Abstract
In this work, we probed the changes to some physicochemical properties of polystyrene microplastics generated from a disposable cup as a result of UV-weathering, using a range of spectroscopy, microscopy, and profilometry techniques. Thereafter, we aimed to understand how these physicochemical changes affect the microplastic transport potential and contaminant sorption ability in model freshwaters. Exposure to UV led to measured changes in microplastic hydrophobicity (20-23 % decrease), density (3% increase), carbonyl index (up to 746 % increase), and microscale roughness (24-86 % increase). The settling velocity of the microplastics increased by 53 % after weathering which suggests that UV aging can increase microplastic deposition to sediments. This impact of aging was greater than the effect of the water temperature. Weathered microplastics exhibited reduced sorption capacity (up to 52 % decrease) to a model hydrophobic contaminant (triclosan) compared to unaged ones. The adsorption of triclosan to both microplastics was slightly reversible with notable desorption hysteresis. These combined effects of weathering could potentially increase the transport potential while decreasing the contaminant transport abilities of microplastics. This work provides new insights on the sorption capacity and mobility of a secondary microplastic, advances our knowledge about their risks in aquatic environments, and the need to use environmentally relevant microplastics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)
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- 2023
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21. Antibacterial Pickering emulsions stabilized by bifunctional hairy nanocellulose.
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Tavakolian M, Koshani R, Tufenkji N, and van de Ven TGM
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- Emulsions, Particle Size, Surface-Active Agents, Escherichia coli, Staphylococcus aureus
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Hypothesis: Pickering emulsions, defined as emulsions that are stabilized by colloidal particles, provide dispersion stability by preventing coalescence of the dispersed phase. In this study, we used a bifunctional hairy nanocellulose (BHNC) bearing both aldehyde and carboxylic acid groups as an stabilizer. We hypothesize that these particles as Pickering stabilizers can effectively reside at the oil-water interface, better than hairy nanocelluloses containing only carboxyl groups or aldehyde groups, and provide long-term stability without the need of any surfactants., Experiments: Varying concentrations of BHNC were tested to explore the optimal concentration that provides emulsion stability. The effects of various preparation conditions such as salt and pH were also studied. Finally, carvacrol, an antibacterial essential oil, was loaded in the oil phase to develop antibacterial emulsions., Findings: It was shown that a 1% BHNC suspension provides 90% and 80% stability for a duration of 30 and 60 days, respectively. A theoretical model using nuclear magnetic resonance relaxometry data is developed to prove that only a monolayer of BHNC covers oil droplets. Increasing the concentration of BHNC decreased the size of oil droplets, which as a result increases the surface area available for monolayer coverage. It was also shown that the antibacterial emulsions are highly effective against Gram-negative (i.e. E. coli) and Gram-positive (i.e. S. aureus) bacteria. Accordingly, BHNC as a highly functionalized bio-derived colloidal particle opens new opportunities for engineering highly stable Pickering emulsions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2023
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22. Tissue Clearing To Localize Microplastics via Three-Dimensional Imaging of Whole Organisms.
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Macairan JR, Nguyen B, Li F, and Tufenkji N
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- Plastics, Imaging, Three-Dimensional, Polystyrenes, Environmental Monitoring, Microplastics, Water Pollutants, Chemical analysis
- Abstract
Understanding the biological impacts of plastic pollution requires an effective methodology to detect unlabeled microplastics in environmental samples. Detecting unlabeled microplastics in an organism generally requires a digestion protocol, which results in the loss of spatial information on the distribution of microplastic within the organism and could lead to the disappearance of the smaller plastics. Fluorescence microscopy allows visualization of ingested microplastics but many labeling strategies are nonspecific and label biomass, thus limiting our ability to distinguish internalized plastics. While prelabeled plastics can be used to avoid nonspecific labeling, this approach precludes the detection of environmental microplastics in organisms. Also, using prelabeled microplastics can affect the viability of the organism and impact plastic uptake. Thus, a method was developed that employs nonspecific labeling with a tissue-clearing technique. Briefly, unlabeled microplastics are stained with a fluorescent dye after ingestion by the organism. The tissue-clearing technique then removes tissue-bound dye while rendering the structurally intact organism transparent. The internalized plastics remain stained and can be visualized in the cleared tissue with fluorescence microscopy. The technique is demonstrated using polystyrene beads in living aquatic organisms Tigriopus californicus and Daphnia magna and by spiking a model vertebrate ( Cephalochordata ) with different microplastics.
- Published
- 2023
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23. Fate of microfibres from single-use face masks: Release to the environment and removal during wastewater treatment.
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Pikuda O, Lapointe M, Alimi OS, Berk D, and Tufenkji N
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- Masks, Plastics, Water Pollutants, Chemical analysis, Water Purification
- Abstract
Single-use face masks can release microfibres upon exposure to environmental conditions. This study investigates the number of microfibres released in the presence and absence of UV irradiation and mechanical friction and the removal of the released microfibres in a simulated conventional wastewater treatment process. UV exposure results in a four-fold increase in the number of microfibres released from new masks and used masks resulting in ~2400 microfibres/mask and ~1100 microfibres/mask, respectively. Application of mechanical friction to the UV-exposed new and used masks further increases the number of released microfibres per mask. In a simulated coagulation/flocculation process, the removals of microfibers originating from new masks and used masks are 79% and 91%, respectively. XPS analysis reveals that the silica content of the used masks is 240% higher than that of new masks, which could explain the higher removal efficiency of microfibers from used masks. FTIR analysis of the masks after UV exposure shows carbonyl indices of 0.73 ± 0.70 and 0.27 ± 0.10 for the microfibres from used and new masks, respectively. Based on available data, we estimate that 4-47 million polypropylene microfibres can be released into natural waters per day after wastewater treatment in an urban environment (for a population of 4300 persons/km
2 )., (Copyright © 2022 Elsevier B.V. All rights reserved.)- Published
- 2022
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24. Fabrication of graphene-based porous materials: traditional and emerging approaches.
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Jahandideh H, Macairan JR, Bahmani A, Lapointe M, and Tufenkji N
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The anisotropic nature of 'graphenic' nanosheets enables them to form stable three-dimensional porous materials. The use of these porous structures has been explored in several applications including electronics and batteries, environmental remediation, energy storage, sensors, catalysis, tissue engineering, and many more. As method of fabrication greatly influences the final pore architecture, and chemical and mechanical characteristics and performance of these porous materials, it is essential to identify and address the correlation between property and function. In this review, we report detailed analyses of the different methods of fabricating porous graphene-based structures - with a focus on graphene oxide as the base material - and relate these with the resultant morphologies, mechanical responses, and common applications of use. We discuss the feasibility of the synthesis approaches and relate the GO concentrations used in each methodology against their corresponding pore sizes to identify the areas not explored to date., Competing Interests: N. T. holds a patent on the use of graphene sponges for water treatment. All other authors have no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2022
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25. Microfluidic Study of Bacterial Attachment on and Detachment from Zinc Oxide Nanopillars.
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Lin N, Valiei A, McKay G, Nguyen D, Tufenkji N, and Moraes C
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- Microfluidics, Pseudomonas aeruginosa, Staphylococcus aureus, Biofouling, Zinc Oxide pharmacology
- Abstract
Nanopillars can influence how bacterial cells attach to a surface. Herein, we investigated whether self-assembled zinc oxide (ZnO) nanopillars synthesized on glass substrates via the conventional hydrothermal route possess anti-biofouling properties either by reducing the amount of initially attached cells or promoting the detachment of cells from the surface or both. To avoid complications associated with manual intervention methods of assessing bacterial attachment on nanopillar surfaces, we implemented a microfluidic approach. In our study, we synthesized two nanopillar topographies: a low surface density of ZnO nanopillars and a high surface density of ZnO nanopillars. Next, we mounted microfluidic channels to each of these substrates. This microfluidic approach allowed us to gently flow Pseudomonas aeruginosa , Staphylococcus aureus , or Bacillus subtilis cells onto the nanopillars for initial attachment before systematically increasing the flowrate to attempt to detach remaining attached cells without introducing air-liquid interface artefacts during the assay. Generally, initial bacterial attachment was similar across all substrates. However, cells consistently detached more readily from high-surface-density nanopillars compared to low-surface-density nanopillars. Electron microscopy revealed that cells that attached to high-surface-density nanopillars rested atop the nanopillars, fully exposed to microfluidic shear, whereas many cells became trapped in the void space between neighboring low-surface-density nanopillars, shielding these cells from detachment. Our findings indicate that self-assembled ZnO nanopillars can provide anti-biofouling properties under submerged flow but only if synthesized at high surface density.
- Published
- 2022
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26. Proanthocyanidin Interferes with Intrinsic Antibiotic Resistance Mechanisms of Gram-Negative Bacteria.
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Maisuria VB, Okshevsky M, Déziel E, and Tufenkji N
- Published
- 2022
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27. Surface Wettability Is a Key Feature in the Mechano-Bactericidal Activity of Nanopillars.
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Valiei A, Lin N, McKay G, Nguyen D, Moraes C, Hill RJ, and Tufenkji N
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- Bacteria, Surface Properties, Water chemistry, Wettability, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents pharmacology, Pseudomonas aeruginosa
- Abstract
Nanopillar-textured surfaces are of growing interest because of their ability to kill bacteria through physical damage without relying on antimicrobial chemicals. Although research on antibacterial nanopillars has progressed significantly in recent years, the effect of nanopillar hydrophobicity on bactericidal activity remains elusive. In this study, we investigated the mechano-bactericidal efficacy of etched silicon nanopillars against Pseudomonas aeruginosa at nanopillar hydrophobicities from superhydrophilic to superhydrophobic. Assessing cell viability and bacterial morphology in immersed wet conditions, we observed negligible bactericidal activity; however, air/liquid interface displacement during water evaporation established a bactericidal effect that strongly depends on substrate hydrophobicity. Specifically, bactericidal activity was highest on superhydrophilic surfaces but abated with increasing hydrophobicity, diminishing at substrate contact angles larger than 90°. Calculation of the surface tension and Laplace pressure forces during water evaporation for each substrate subsequently highlighted that the total capillary force, as an external driving force responsible for bacterial deformation, is significantly weaker on hydrophobic substrates. These findings suggest that superhydrophilic nanopillared surfaces are a superior choice for mechano-bactericidal activity, whereas superhydrophobic surfaces, although not bactericidal, may have antibiofouling properties through their self-cleaning effect. These findings provide new insights into the design and application of nanopillared surfaces as functional antibacterial materials.
- Published
- 2022
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28. Single-Particle Resolution Fluorescence Microscopy of Nanoplastics.
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Nguyen B and Tufenkji N
- Subjects
- Animals, Caenorhabditis elegans, Microscopy, Fluorescence, Microplastics, Plastics
- Abstract
Understanding of nanoplastic prevalence and toxicology is limited by imaging challenges resulting from their small size. Fluorescence microscopy is widely applied to track and identify microplastics in laboratory studies and environmental samples. However, conventional fluorescence microscopy, due to diffraction, lacks the resolution to precisely localize nanoplastics in tissues, distinguish them from free dye, or quantify them in environmental samples. To address these limitations, we developed techniques to label nanoplastics for imaging with stimulated emission depletion (STED) microscopy to achieve resolution at an order of magnitude superior to conventional fluorescence microscopy. These techniques include (1) passive sorption; (2) swell incorporation; and (3) covalent coupling of STED-compatible fluorescence dyes to nanoplastics. We demonstrate that our labeling techniques, combined with STED microscopy, can be used to resolve nanoplastics of different shapes and compositions as small as 50 nm. The longevity of dye labeling is demonstrated in different media and conditions of biological and environmental relevance. We also test STED imaging of nanoplastics in exposure experiments with the model worm Caenorhabditis elegans . Our work shows the value of the method for detection and localization of nanoplastics as small as 50 nm in a whole animal without disruption of the tissue. These techniques will allow more precise localization and quantification of nanoplastics in complex matrices such as biological tissues in exposure studies.
- Published
- 2022
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29. Metabolic Consequences of Developmental Exposure to Polystyrene Nanoplastics, the Flame Retardant BDE-47 and Their Combination in Zebrafish.
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Chackal R, Eng T, Rodrigues EM, Matthews S, Pagé-Lariviére F, Avery-Gomm S, Xu EG, Tufenkji N, Hemmer E, and Mennigen JA
- Abstract
Single-use plastic production is higher now than ever before. Much of this plastic is released into aquatic environments, where it is eventually weathered into smaller nanoscale plastics. In addition to potential direct biological effects, nanoplastics may also modulate the biological effects of hydrophobic persistent organic legacy contaminants (POPs) that absorb to their surfaces. In this study, we test the hypothesis that developmental exposure (0-7 dpf) of zebrafish to the emerging contaminant polystyrene (PS) nanoplastics (⌀100 nm; 2.5 or 25 ppb), or to environmental levels of the legacy contaminant and flame retardant 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47; 10 ppt), disrupt organismal energy metabolism. We also test the hypothesis that co-exposure leads to increased metabolic disruption. The uptake of nanoplastics in developing zebrafish was validated using fluorescence microscopy. To address metabolic consequences at the organismal and molecular level, metabolic phenotyping assays and metabolic gene expression analysis were used. Both PS and BDE-47 affected organismal metabolism alone and in combination. Individually, PS and BDE-47 exposure increased feeding and oxygen consumption rates. PS exposure also elicited complex effects on locomotor behaviour with increased long-distance and decreased short-distance movements. Co-exposure of PS and BDE-47 significantly increased feeding and oxygen consumption rates compared to control and individual compounds alone, suggesting additive or synergistic effects on energy balance, which was further supported by reduced neutral lipid reserves. Conversely, molecular gene expression data pointed to a negative interaction, as co-exposure of high PS generally abolished the induction of gene expression in response to BDE-47. Our results demonstrate that co-exposure to emerging nanoplastic contaminants and legacy contaminants results in cumulative metabolic disruption in early development in a fish model relevant to eco- and human toxicology., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chackal, Eng, Rodrigues, Matthews, Pagé-Lariviére, Avery-Gomm, Xu, Tufenkji, Hemmer and Mennigen.)
- Published
- 2022
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30. Weathering pathways and protocols for environmentally relevant microplastics and nanoplastics: What are we missing?
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Alimi OS, Claveau-Mallet D, Kurusu RS, Lapointe M, Bayen S, and Tufenkji N
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- Environmental Monitoring, Plastics toxicity, Reproducibility of Results, Weather, Microplastics, Water Pollutants, Chemical analysis, Water Pollutants, Chemical toxicity
- Abstract
To date, most studies of microplastics have been carried out with pristine particles. However, most plastics in the environment will be aged to some extent; hence, understanding the effects of weathering and accurately mimicking weathering processes are crucial. By using microplastics that lack environmental relevance, we are unable to fully assess the risks associated with microplastic pollution in the environment. Emerging studies advocate for harmonization of experimental methods, however, the subject of reliable weathering protocols for realistic assessment has not been addressed. In this work, we critically analysed the current knowledge regarding protocols used for generating environmentally relevant microplastics and leachates for effects studies. We present the expected and overlooked weathering pathways that plastics will undergo throughout their lifecycle. International standard weathering protocols developed for polymers were critically analysed for their appropriateness for use in microplastics research. We show that most studies using weathered microplastics involve sorption experiments followed by toxicity assays. The most frequently reported weathered plastic types in the literature are polystyrene>polyethylene>polypropylene>polyvinyl chloride, which does not reflect the global plastic production and plastic types detected globally. Only ~10% of published effect studies have used aged microplastics and of these, only 12 use aged nanoplastics. This highlights the need to embrace the use of environmentally relevant microplastics and to pay critical attention to the appropriateness of the weathering methods adopted moving forward. We advocate for quality reporting of weathering protocols and characterisation for harmonization and reproducibility across different research efforts., (Copyright © 2021 Elsevier B.V. All rights reserved.)
- Published
- 2022
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31. Green synthesis of carbon dots and their applications.
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Chahal S, Macairan JR, Yousefi N, Tufenkji N, and Naccache R
- Abstract
Carbon dots (CDs) are nanoparticles with tunable physicochemical and optical properties. Their resistance to photobleaching and relatively low toxicity render them attractive alternatives to fluorescent dyes and heavy metal-based quantum dots in the fields of bioimaging, sensing, catalysis, solar cells, and light-emitting diodes, among others. Moreover, they have garnered considerable attention as they lend themselves to green synthesis methods. Increasingly, one-pot syntheses comprising exclusively of renewable raw materials or renewable refined compounds are gaining favor over traditional approaches that rely on harsh chemicals and energy intensive conditions. The field of green CD synthesis is developing rapidly; however, challenges persist in ensuring the consistency of their properties ( e.g. , fluorescence quantum yield) relative to conventional preparation methods. This has mostly limited their use to sensing and bioimaging, leaving opportunities for development in optoelectronic applications. Herein, we discuss the most common green CD synthesis and purification methods reported in the literature and the renewable precursors used. The physical, chemical, and optical properties of the resulting green-synthesized CDs are critically reviewed, followed by a detailed description of their applications in sensing, bioimaging, biomedicine, inks, and catalysis. We conclude with an outlook on the future of green CD synthesis. Future research efforts should address the broad knowledge gap between CDs synthesized from renewable versus non-renewable precursors, focusing on discrepancies in their physical, chemical, and optical properties. The development of cost effective, safe, and sustainable green CDs with tunable properties will broaden their implementation in largely untapped applications, which include drug delivery, photovoltaics, catalysis, and more., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
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- 2021
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32. Nanoplastics are neither microplastics nor engineered nanoparticles.
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Gigault J, El Hadri H, Nguyen B, Grassl B, Rowenczyk L, Tufenkji N, Feng S, and Wiesner M
- Abstract
Increasing concern and research on the subject of plastic pollution has engaged the community of scientists working on the environmental health and safety of nanomaterials. While many of the methods developed in nano environment, health and safety work have general applicability to the study of particulate plastics, the nanometric size range has important consequences for both the analytical challenges of studying nanoscale plastics and the environmental implications of these incidental nanomaterials. Related to their size, nanoplastics are distinguished from microplastics with respect to their transport properties, interactions with light and natural colloids, a high fraction of particle molecules on the surface, bioavailability and diffusion times for the release of plastic additives. Moreover, they are distinguished from engineered nanomaterials because of their high particle heterogeneity and their potential for rapid further fragmentation in the environment. These characteristics impact environmental fate, potential effects on biota and human health, sampling and analysis. Like microplastics, incidentally produced nanoplastics exhibit a diversity of compositions and morphologies and a heterogeneity that is typically absent from engineered nanomaterials. Therefore, nanoscale plastics must be considered as distinct from both microplastics and engineered nanomaterials.
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- 2021
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33. Cranberry-Derived Proanthocyanidins Potentiate β-Lactam Antibiotics against Resistant Bacteria.
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Gallique M, Wei K, Maisuria VB, Okshevsky M, McKay G, Nguyen D, and Tufenkji N
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- Bacteria growth & development, Drug Synergism, beta-Lactam Resistance drug effects, Ampicillin pharmacology, Anti-Bacterial Agents pharmacology, Bacteria drug effects, Cefotaxime pharmacology, Proanthocyanidins pharmacology, Vaccinium macrocarpon
- Abstract
The emergence and spread of extended-spectrum β-lactamases (ESBLs), metallo-β-lactamases (MBLs), or variant low-affinity penicillin-binding proteins (PBPs) pose a major threat to our ability to treat bacterial infection using β-lactam antibiotics. Although combinations of β-lactamase inhibitors with β-lactam agents have been clinically successful, there are no MBL inhibitors in current therapeutic use. Furthermore, recent clinical use of new-generation cephalosporins targeting PBP2a, an altered PBP, has led to the emergence of resistance to these antimicrobial agents. Previous work shows that natural polyphenols such as cranberry-extracted proanthocyanidins (cPAC) can potentiate non-β-lactam antibiotics against Gram-negative bacteria. This study extends beyond previous work by investigating the in vitro effect of cPAC in overcoming ESBL-, MBL-, and PBP2a-mediated β-lactam resistance. The results show that cPAC exhibit variable potentiation of different β-lactams against β-lactam-resistant Enterobacteriaceae clinical isolates as well as ESBL- and MBL-producing E. coli We also discovered that cPAC have broad-spectrum inhibitory properties in vitro on the activity of different classes of β-lactamases, including CTX-M3 ESBL and IMP-1 MBL. Furthermore, we observe that cPAC selectively potentiate oxacillin and carbenicillin against methicillin-resistant but not methicillin-sensitive staphylococci, suggesting that cPAC also interfere with PBP2a-mediated resistance. This study motivates the need for future work to identify the most bioactive compounds in cPAC and to evaluate their antibiotic-potentiating efficacy in vivo IMPORTANCE The emergence of β-lactam-resistant Enterobacteriaceae and staphylococci compromises the effectiveness of β-lactam-based therapy. By acquisition of ESBLs, MBLs, or PBPs, it is highly likely that bacteria may become completely resistant to the most effective β-lactam agents in the near future. In this study, we described a natural extract rich in proanthocyanidins which exerts adjuvant properties by interfering with two different resistance mechanisms. By their broad-spectrum inhibitory ability, cranberry-extracted proanthocyanidins could have the potential to enhance the effectiveness of existing β-lactam agents., (Copyright © 2021 American Society for Microbiology.)
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- 2021
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34. Correction to "Amendment of Agricultural Soil with Metal Nanoparticles: Effects on Soil Enzyme Activity and Microbial Community Composition".
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Asadishad B, Chahal S, Akbari A, Cianciarelli V, Azodi M, Ghoshal S, and Tufenkji N
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- 2021
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35. Exposure of nanoplastics to freeze-thaw leads to aggregation and reduced transport in model groundwater environments.
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Alimi OS, Farner JM, and Tufenkji N
- Subjects
- Freezing, Plastics, Polystyrenes, Groundwater, Microplastics
- Abstract
Despite plastic pollution being a significant environmental concern, the impact of environmental conditions such as temperature cycling on the fate of nanoplastics in cold climates remains unknown. To better understand nanoplastic mobility in subsurface environments following freezing and thawing cycles, the transport of 28 nm polystyrene nanoplastics exposed to either constant (10°C) temperature or freeze-thaw (FT) cycles (-10°C to 10°C) was investigated in saturated quartz sand. The stability and transport of nanoplastic suspensions were examined both in the presence and absence of natural organic matter (NOM) over a range of ionic strengths (3-100 mM NaCl). Exposure to 10 FT cycles consistently led to significant aggregation and reduced mobility compared to nanoplastics held at 10°C, especially at low ionic strengths in the absence of NOM. While NOM increased nanoplastic mobility, it did not prevent the aggregation of nanoplastics exposed to FT. We compare our findings with existing literature and show that nanoplastics will largely aggregate and associate with soils rather than undergo long range transport in groundwater in colder climates following freezing temperatures. In fact, FT exposure leads to the formation of stable aggregates that are not prone to disaggregation. As one of the first studies to examine the coupled effect of cold temperature and NOM, this work highlights the need to account for climate and temperature changes when assessing the risks associated with nanoplastic release in aquatic systems., Competing Interests: Declaration of Competing Interest There is no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)
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- 2021
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36. Polymer-Free Emulsion-Templated Graphene-Based Sponges for Contaminant Removal.
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Jahandideh H, Nguyen QA, and Tufenkji N
- Abstract
An emulsion-templated porous material can be formed by polymerizing the continuous phase of high internal phase Pickering emulsions (HIPEs). Although polymerization is a key step to maintain the pore size and integrity of the final sponge, it lowers the effective specific surface area of the final sponge as the continuous phase makes up at least half of the HIPE's volume. Hence, eliminating the need of polymerization not only eases the material processing but also leads to a greater specific surface area. Here, we report a novel strategy in which none of the emulsion phases require polymerization and is therefore a versatile methodology. For this purpose, several oil-in-water Pickering emulsions were prepared using graphene oxide (GO) and cellulose nanocrystals (CNCs) as the stabilizing agents. GO nanosheets are then reduced by mixing the emulsions with an adequate amount of vitamin C as a green reducing agent. Removal of the oil phase via multiple washing and boiling steps results in the formation of the ultimate reduced graphene oxide (rGO)/CNC sponge. The integrity of the structure remains intact and results in the formation of pores that are comparable in size to the droplets because of (i) the strong adhesion of GO and CNC at the oil/water interface in the initial Pickering emulsions and (ii) the strong intermolecular interactions between GO and CNC particles within the water phase. The sponge was then evaluated for its contaminant removal applicability using methylene blue and found to be effective in different water chemistries and outperform previously reported poly(HIPEs) and granular activated carbon. This is the first report on the formation of a polymer-free emulsion-templated sponge, and we believe that this novel nanomaterial paves the road for the fabrication of other emulsion-templated sponges. Although the proposed application in this work is contaminant removal, it could also be utilized in forming electronic devices and sensors because of the incorporation of rGO as a conductive component.
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- 2020
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37. Response to Comment on "Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea".
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Hernandez LM, Xu EG, Larsson HCE, Tahara R, Maisuria VB, and Tufenkji N
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- Plastics, Tea, Chitosan, Nanoparticles
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- 2020
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38. Highly Absorbent Antibacterial and Biofilm-Disrupting Hydrogels from Cellulose for Wound Dressing Applications.
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Tavakolian M, Munguia-Lopez JG, Valiei A, Islam MS, Kinsella JM, Tufenkji N, and van de Ven TGM
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- Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents chemistry, Bandages, Biofilms drug effects, Cellulose chemistry, Dose-Response Relationship, Drug, Hydrogels chemical synthesis, Hydrogels chemistry, Microbial Sensitivity Tests, Molecular Structure, Particle Size, Surface Properties, Anti-Bacterial Agents pharmacology, Cellulose pharmacology, Hydrogels pharmacology, Pseudomonas aeruginosa drug effects, Staphylococcus aureus drug effects, Wound Healing drug effects
- Abstract
In this study, a carboxyl-modified cellulosic hydrogel was developed as the base material for wound dressings. ε-poly-l-lysine, a natural polyamide, was then covalently linked to the hydrogel through a bioconjugation reaction, which was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). The antibacterial efficacy of the hydrogel was tested against two model bacteria, Staphylococcus aureus and Pseudomonas aeruginosa , two of the most commonly found bacteria in wound infections. Bacterial viability and biofilm formation after exposure of bacteria to the hydrogels were used as efficacy indicators. Live/Dead assay was used to measure the number of compromised bacteria using a confocal laser scanning microscope. The results show that the antibacterial hydrogel was able to kill approximately 99% of the exposed bacteria after 3 h of exposure. In addition, NIH/3T3 fibroblasts were used to study the biocompatibility of the developed hydrogels. Water-soluble tetrazolium salt (WST)-1 assay was used to measure the metabolic activity of the cells and Live/Dead assay was used to measure the viability of the cells after 24, 48, and 72 h. The developed antibacterial hydrogels are light weight, have a high water-uptake capacity, and show high biocompatibility with the model mammalian cells, which make them a promising candidate to be used for wound dressing applications.
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- 2020
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39. Hydrophilic Mechano-Bactericidal Nanopillars Require External Forces to Rapidly Kill Bacteria.
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Valiei A, Lin N, Bryche JF, McKay G, Canva M, Charette PG, Nguyen D, Moraes C, and Tufenkji N
- Subjects
- Anti-Bacterial Agents pharmacology, Bacteria, Nanotechnology, Surface Properties, Nanostructures
- Abstract
Nanopillars have been shown to mechanically damage bacteria, suggesting a promising strategy for future antibacterial surfaces. However, the mechanisms underlying this phenomena remain unclear, which ultimately limits translational potential toward real-world applications. Using real-time and end-point analysis techniques, we demonstrate that in contrast to initial expectations, bacteria on multiple hydrophilic "mechano-bactericidal" surfaces remained viable unless exposed to a moving air-liquid interface, which caused considerable cell death. Reasoning that normal forces arising from surface tension may underlie this mechano-bactericidal activity, we developed computational and experimental models to estimate, manipulate, and recreate the impact of these forces. Our experiments together demonstrate that a critical level of external force acting on cells attached to nanopillar surfaces can rapidly deform and rupture bacteria. These studies provide fundamental physical insight into how nanopillar surfaces can serve as effective antibacterial materials and suggest use-conditions under which such nanotechnology approaches may provide practical value.
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- 2020
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40. Understanding and Improving Microplastic Removal during Water Treatment: Impact of Coagulation and Flocculation.
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Lapointe M, Farner JM, Hernandez LM, and Tufenkji N
- Subjects
- Flocculation, Microplastics, Waste Disposal, Fluid, Water, Plastics, Water Purification
- Abstract
The efficacy of plastic particle removal by municipal water treatment plants is currently uncertain, and the mechanisms involved in microplastic (MP) coagulation and flocculation have only been superficially investigated. The removal of pristine versus weathered plastic debris and the impact of plastic particle size on removal remain largely unexplored. In this study, coagulation, flocculation, and settling performances were investigated using pristine and weathered MPs (polyethylene (PE) and polystyrene (PS) microspheres, and polyester (PEST) fibers). Weathering processes that changed the surface chemistry and roughness of MPs impacted MP affinity for coagulants and flocculants. A quartz crystal microbalance with dissipation monitoring was used to identify the mechanisms involved during MP coagulation and flocculation. Measured deposition rates confirmed the relatively low affinity between plastic surfaces and aluminum-based coagulants compared to cationic polyacrylamide (PAM). In every case examined, coagulant efficiency increased when the plastic surface was weathered. Removals of 97 and 99% were measured for PEST and weathered PE, respectively. Larger pristine PE MPs were the most resistant to coagulation and flocculation, with 82% removal observed even under enhanced coagulation conditions. By understanding the interaction mechanisms, the removal of weathered MPs was optimized. Finally, this study explored the use of settled water turbidity as a possible indicator of MP removal.
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- 2020
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41. Correction for Maisuria et al., "Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria".
- Author
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Maisuria VB, Hosseinidoust Z, and Tufenkji N
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- 2020
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42. Primary and Secondary Plastic Particles Exhibit Limited Acute Toxicity but Chronic Effects on Daphnia magna .
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Xu EG, Cheong RS, Liu L, Hernandez LM, Azimzada A, Bayen S, and Tufenkji N
- Subjects
- Animals, Fresh Water, Humans, Infant, Newborn, Plastics toxicity, Polystyrenes toxicity, Reproduction, Daphnia, Water Pollutants, Chemical analysis, Water Pollutants, Chemical toxicity
- Abstract
Nanoplastics (NPs; <0.1 μm) are speculated to be a bigger ecological threat due to their predicted wider distribution, higher concentrations, and bioavailability. Primary NPs are manufactured to be that size, while secondary NPs originate from fragmentation of bigger debris. To date, the long-term impact of NPs in freshwater systems, particularly secondary NPs, is not well-understood. Thus, we employed a freshwater invertebrate, Daphnia magna , to investigate the chronic effects of model primary NPs, fluorescent polystyrene nanospheres (PS-NPs; 20 nm), and water leachate of weathered single-use plastics that contained micro- and nanosized particles. In experiment 1, parent Daphnia (F0) were exposed to 1 and 50 mg/L PS-NPs until the production of the neonates (F1) followed by a two-generation recovery. PS-NPs were mainly detected in the intestine and brood chamber in F0 and transferred to F1 and F2. PS-NPs significantly decreased the appendage curling and heartbeat rate in F0 and reduced reproduction in F2. In experiment 2, the plastic leachate also reduced the appendage curling rate but increased growth and reproduction. The results suggest that the acute toxicity of primary and secondary plastic particles is low even at high concentrations, but their chronic and sublethal effects should not be overlooked.
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- 2020
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43. Reply to the 'Comment on "Hierarchically porous, ultra-strong reduced graphene oxide-cellulose nanocrystal sponges for exceptional adsorption of water contaminants"' by J. Ma, Y. Xiong and F. Yu, Nanoscale, 2019, 11, DOI: 10.1039/C8NR08780F.
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Yousefi N and Tufenkji N
- Abstract
We respond to the comments of Ma et al. and clarify the rationale behind our methodology and why it is suitable for our work.
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- 2020
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44. Biofilm formation by marine bacteria is impacted by concentration and surface functionalization of polystyrene nanoparticles in a species-specific manner.
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Okshevsky M, Gautier E, Farner JM, Schreiber L, and Tufenkji N
- Subjects
- Aquatic Organisms drug effects, Aquatic Organisms growth & development, Nanoparticles, Oceans and Seas, Plastics chemistry, Plastics pharmacology, Seawater microbiology, Bacteria drug effects, Bacteria growth & development, Biofilms drug effects, Biofilms growth & development, Polystyrenes pharmacology, Water Pollutants chemistry, Water Pollutants pharmacology
- Abstract
The world's oceans are becoming increasingly polluted by plastic waste. In the marine environment, larger plastic pieces may degrade into nanoscale (<100 nm in at least one dimension) plastic particles due to natural weathering effects. We observe that the presence of 20 nm plastic nanoparticles at concentrations below 200 ppm had no impact on planktonic growth of a panel of heterotrophic marine bacteria. However, the presence of plastic nanoparticles significantly impacted the formation of biofilms in a species-specific manner. While carboxylated nanoparticles increased the amount of biofilm formed by several species, amidine-functionalized nanoparticles decreased the amount of biofilm of many but not all bacteria. Further experiments suggested that the aggregation dynamics of bacteria and nanoparticles were strongly impacted by the surface properties of the nanoparticles. The community structure of an artificially constructed community of marine bacteria was significantly altered by exposure to plastic nanoparticles, with differently functionalized nanoparticles selecting for unique and reproducible community abundance patterns. These results suggest that surface properties and concentration of plastic nanoparticles, as well as species interactions, are important factors determining how plastic nanoparticles impact biofilm formation by marine bacteria., (© 2020 Society for Applied Microbiology and John Wiley & Sons Ltd.)
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- 2020
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45. Artificial turf infill associated with systematic toxicity in an amniote vertebrate.
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Xu EG, Lin N, Cheong RS, Ridsdale C, Tahara R, Du TY, Das D, Zhu J, Peña Silva L, Azimzada A, Larsson HCE, and Tufenkji N
- Subjects
- Animals, Brain drug effects, Brain embryology, Cardiovascular System drug effects, Cardiovascular System embryology, Chick Embryo, Embryonic Development, Environmental Health, Recycling, Toxicity Tests, Construction Materials toxicity, Environmental Exposure analysis, Rubber toxicity
- Abstract
Artificial athletic turf containing crumb rubber (CR) from shredded tires is a growing environmental and public health concern. However, the associated health risk is unknown due to the lack of toxicity data for higher vertebrates. We evaluated the toxic effects of CR in a developing amniote vertebrate embryo. CR water leachate was administered to fertilized chicken eggs via different exposure routes, i.e., coating by dropping CR leachate on the eggshell; dipping the eggs into CR leachate; microinjecting CR leachate into the air cell or yolk. After 3 or 7 d of incubation, embryonic morphology, organ development, physiology, and molecular pathways were measured. The results showed that CR leachate injected into the yolk caused mild to severe developmental malformations, reduced growth, and specifically impaired the development of the brain and cardiovascular system, which were associated with gene dysregulation in aryl hydrocarbon receptor, stress-response, and thyroid hormone pathways. The observed systematic effects were probably due to a complex mixture of toxic chemicals leaching from CR, such as metals (e.g., Zn, Cr, Pb) and amines (e.g., benzothiazole). This study points to a need to closely examine the potential regulation of the use of CR on playgrounds and artificial fields., Competing Interests: Competing interest statement: The authors declare no competing interest.
- Published
- 2019
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46. Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea.
- Author
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Hernandez LM, Xu EG, Larsson HCE, Tahara R, Maisuria VB, and Tufenkji N
- Subjects
- Environmental Monitoring, Nylons, Plastics, Spectroscopy, Fourier Transform Infrared, Tea, Nanoparticles, Water Pollutants, Chemical
- Abstract
The increasing presence of micro- and nano-sized plastics in the environment and food chain is of growing concern. Although mindful consumers are promoting the reduction of single-use plastics, some manufacturers are creating new plastic packaging to replace traditional paper uses, such as plastic teabags. The objective of this study was to determine whether plastic teabags could release microplastics and/or nanoplastics during a typical steeping process. We show that steeping a single plastic teabag at brewing temperature (95 °C) releases approximately 11.6 billion microplastics and 3.1 billion nanoplastics into a single cup of the beverage. The composition of the released particles is matched to the original teabags (nylon and polyethylene terephthalate) using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The levels of nylon and polyethylene terephthalate particles released from the teabag packaging are several orders of magnitude higher than plastic loads previously reported in other foods. An initial acute invertebrate toxicity assessment shows that exposure to only the particles released from the teabags caused dose-dependent behavioral and developmental effects.
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- 2019
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47. Microfluidic Shear Assay to Distinguish between Bacterial Adhesion and Attachment Strength on Stiffness-Tunable Silicone Substrates.
- Author
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Siddiqui S, Chandrasekaran A, Lin N, Tufenkji N, and Moraes C
- Subjects
- Bacterial Adhesion, Coated Materials, Biocompatible chemical synthesis, Particle Size, Shear Strength, Surface Properties, Coated Materials, Biocompatible chemistry, Escherichia coli K12 chemistry, Microfluidic Analytical Techniques, Silicones chemistry
- Abstract
Tuning surface composition and stiffness is now an established strategy to improve the integration of medical implants. Recent evidence suggests that matrix stiffness affects bacterial adhesion, but contradictory findings have been reported in the literature. Distinguishing between the effects of bacterial adhesion and attachment strength on these surfaces may help interpret these findings. Here, we develop a precision microfluidic shear assay to quantify bacterial adhesion strength on stiffness-tunable and biomolecule-coated silicone materials. We demonstrate that bacteria are more strongly attached to soft silicones, compared to stiff silicones; as determined by retention against increasing shear flows. Interestingly, this effect is reduced when the surface is coated with matrix biomolecules. These results demonstrate that bacteria do sense and respond to stiffness of the surrounding environment and that precisely defined assays are needed to understand the interplay among surface mechanics, composition, and bacterial binding.
- Published
- 2019
- Full Text
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48. Nano-enabled strategies to enhance crop nutrition and protection.
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Kah M, Tufenkji N, and White JC
- Subjects
- Humans, Risk Assessment, Agriculture methods, Agriculture trends, Crop Production methods, Crop Production trends, Food Supply methods, Nanotechnology methods, Nanotechnology trends
- Abstract
Various nano-enabled strategies are proposed to improve crop production and meet the growing global demands for food, feed and fuel while practising sustainable agriculture. After providing a brief overview of the challenges faced in the sector of crop nutrition and protection, this Review presents the possible applications of nanotechnology in this area. We also consider performance data from patents and unpublished sources so as to define the scope of what can be realistically achieved. In addition to being an industry with a narrow profit margin, agricultural businesses have inherent constraints that must be carefully considered and that include existing (or future) regulations, as well as public perception and acceptance. Directions are also identified to guide future research and establish objectives that promote the responsible and sustainable development of nanotechnology in the agri-business sector.
- Published
- 2019
- Full Text
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49. Proanthocyanidin Interferes with Intrinsic Antibiotic Resistance Mechanisms of Gram-Negative Bacteria.
- Author
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Maisuria VB, Okshevsky M, Déziel E, and Tufenkji N
- Abstract
Antibiotic resistance is spreading at an alarming rate among pathogenic bacteria in both medicine and agriculture. Interfering with the intrinsic resistance mechanisms displayed by pathogenic bacteria has the potential to make antibiotics more effective and decrease the spread of acquired antibiotic resistance. Here, it is demonstrated that cranberry proanthocyanidin (cPAC) prevents the evolution of resistance to tetracycline in Escherichia coli and Pseudomonas aeruginosa , rescues antibiotic efficacy against antibiotic-exposed cells, and represses biofilm formation. It is shown that cPAC has a potentiating effect, both in vitro and in vivo, on a broad range of antibiotic classes against pathogenic E. coli , Proteus mirabilis , and P. aeruginosa . Evidence that cPAC acts by repressing two antibiotic resistance mechanisms, selective membrane permeability and multidrug efflux pumps, is presented. Failure of cPAC to potentiate antibiotics against efflux pump-defective mutants demonstrates that efflux interference is essential for potentiation. The use of cPAC to potentiate antibiotics and mitigate the development of resistance could improve treatment outcomes and help combat the growing threat of antibiotic resistance., Competing Interests: Authors Nathalie Tufenkji and Vimal B. Maisuria have applied for a patent (WO 2017/096484) on the use of cranberry derived phenolic compounds as antibiotic synergizing agent against pathogenic bacteria. The patent application is presently under review by the USPTO, with both authors listed as inventors. All authors declare that they have no other conflicts of interest.
- Published
- 2019
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50. Separation and Analysis of Microplastics and Nanoplastics in Complex Environmental Samples.
- Author
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Nguyen B, Claveau-Mallet D, Hernandez LM, Xu EG, Farner JM, and Tufenkji N
- Subjects
- Aquatic Organisms chemistry, Aquatic Organisms metabolism, Hydrophobic and Hydrophilic Interactions, Magnetic Fields, Mass Spectrometry, Microplastics analysis, Microplastics isolation & purification, Microplastics metabolism, Particle Size, Plastics isolation & purification, Plastics metabolism, Waste Disposal, Fluid methods, Wastewater analysis, Water Pollutants, Chemical analysis, Water Pollutants, Chemical isolation & purification, Water Pollutants, Chemical metabolism, Nanostructures chemistry, Plastics analysis
- Abstract
The vast amount of plastic waste emitted into the environment and the increasing concern of potential harm to wildlife has made microplastic and nanoplastic pollution a growing environmental concern. Plastic pollution has the potential to cause both physical and chemical harm to wildlife directly or via sorption, concentration, and transfer of other environmental contaminants to the wildlife that ingest plastic. Small particles of plastic pollution, termed microplastics (>100 nm and <5 mm) or nanoplastics (<100 nm), can form through fragmentation of larger pieces of plastic. These small particles are especially concerning because of their high specific surface area for sorption of contaminants as well as their potential to translocate in the bodies of organisms. These same small particles are challenging to separate and identify in environmental samples because their size makes handling and observation difficult. As a result, our understanding of the environmental prevalence of nanoplastics and microplastics is limited. Generally, the smaller the size of the plastic particle, the more difficult it is to separate from environmental samples. Currently employed passive density and size separation techniques to isolate plastics from environmental samples are not well suited to separate microplastics and nanoplastics. Passive flotation is hindered by the low buoyancy of small particles as well as the difficulty of handling small particles on the surface of flotation media. Here we suggest exploring alternative techniques borrowed from other fields of research to improve separation of the smallest plastic particles. These techniques include adapting active density separation (centrifugation) from cell biology and taking advantage of surface-interaction-based separations from analytical chemistry. Furthermore, plastic pollution is often challenging to quantify in complex matrices such as biological tissues and wastewater. Biological and wastewater samples are important matrices that represent key points in the fate and sources of plastic pollution, respectively. In both kinds of samples, protocols need to be optimized to increase throughput, reduce contamination potential, and avoid destruction of plastics during sample processing. To this end, we recommend adapting digestion protocols to match the expected composition of the nonplastic material as well as taking measures to reduce and account for contamination. Once separated, plastics in an environmental sample should ideally be characterized both visually and chemically. With existing techniques, microplastics and nanoplastics are difficult to characterize or even detect. Their low mass and small size provide limited signal for visual, vibrational spectroscopic, and mass spectrometric analyses. Each of these techniques involves trade-offs in throughput, spatial resolution, and sensitivity. To accurately identify and completely quantify microplastics and nanoplastics in environmental samples, multiple analytical techniques applied in tandem are likely to be required.
- Published
- 2019
- Full Text
- View/download PDF
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