Publications by authors named "Vahid Adibnia"

9 Publications

  • Page 1 of 1

Phytoglycogen Nanoparticles: Nature-Derived Superlubricants.

ACS Nano 2021 05 7;15(5):8953-8964. Epub 2021 May 7.

Department of Chemistry, University of Toronto, Toronto, Ontario, Canada, M5S 3H6.

Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak- to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10. In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10. Analysis of the water content and energy dissipation in the confined NP film reveals that the lubrication is governed by synergistic contributions of unbound and bound water molecules, with the former contributing to lubrication properties in the weak- to moderate-confinement regime and the latter being responsible for the lubrication in the strong-confinement regime. These results unravel mechanistic insights that are essential for the design of lubricating systems based on strongly hydrated NPs.
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http://dx.doi.org/10.1021/acsnano.1c01755DOI Listing
May 2021

Plasmon-Free Polymeric Nanowrinkled Substrates for Surface-Enhanced Raman Spectroscopy of Two-Dimensional Materials.

Langmuir 2021 Jan 21;37(1):322-329. Epub 2020 Dec 21.

Department of Chemical Engineering, Faculty of Engineering & Architectural Science, Ryerson University, Toronto, Ontario M5B 2K3, Canada.

We report plasmon-free polymeric nanowrinkled substrates for surface-enhanced Raman spectroscopy (SERS). Our simple, rapid, and cost-effective fabrication method involves depositing a poly(ethylene glycol)diacrylate (PEGDA) prepolymer solution droplet on a fully polymerized, flat PEGDA substrate, followed by drying the droplet at room conditions and plasma treatment, which polymerizes the deposited layer. The thin polymer layer buckles under axial stress during plasma treatment due to its different mechanical properties from the underlying soft substrate, creating hierarchical wrinkled patterns. We demonstrate the variation of the wrinkling wavelength with the drying polymer molecular weight and concentration (direct relations are observed). A transition between micron to nanosized wrinkles is observed at 5 v % concentration of the lower molecular-weight polymer solution (PEGDA 250). The wrinkled substrates are observed to be reproducible, stable (at room conditions), and, especially, homogeneous at and below the transition regime, where nanowrinkles dominate, making them suitable candidates for SERS. As a proof-of-concept, the enhanced SERS performance of micro/nanowrinkled surfaces in detecting graphene and hexagonal boron nitride (h-BN) is illustrated. Compared to the SiO/Si surfaces, the wrinkled PEGDA substrates significantly enhanced the signature Raman band intensities of graphene and h-BN by a factor of 8 and 50, respectively.
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http://dx.doi.org/10.1021/acs.langmuir.0c02912DOI Listing
January 2021

Superlubricity of Zwitterionic Bottlebrush Polymers in the Presence of Multivalent Ions.

J Am Chem Soc 2020 09 19;142(35):14843-14847. Epub 2020 Aug 19.

Faculty of Pharmacy, Université de Montréal, 2900 Édouard-Montpetit, Montreal, Quebec H3C 3J7, Canada.

In this study, we report lubrication properties of physisorbed zwitterionic bottlebrush polymers in the presence of multivalent ions using the surface force apparatus. Unlike polyelectrolyte brushes, the lubrication properties of which diminish drastically in the presence of multivalent ions at concentrations as low as 0.1 mM, zwitterionic bottlebrush polymers exhibit friction coefficients as low as ∼10 at such concentrations of multivalent ions up to intermediate normal loads. This lubrication ability persists until surface wear occurs at high normal loads. The surface wear is demonstrated to be triggered by the multivalent ions bridging the polymer chains and dehydrating the zwitterionic moieties. Finally, the analysis of the polymer film stability suggests that the partial desorption of polymers in the presence of the ions does not affect the lubrication performance. Therefore, even in the physisorbed state, zwitterionic brushes perform significantly better than covalently grafted polyelectrolyte brushes in the presence of multivalent ions.
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http://dx.doi.org/10.1021/jacs.0c07215DOI Listing
September 2020

Spontaneous shrinking of soft nanoparticles boosts their diffusion in confined media.

Nat Commun 2019 09 20;10(1):4294. Epub 2019 Sep 20.

Faculty of Pharmacy, Université de Montréal, PO Box 6128, Succursale Centre-ville, Montréal, QC, H3C 3J7, Canada.

Improving nanoparticles (NPs) transport across biological barriers is a significant challenge that could be addressed through understanding NPs diffusion in dense and confined media. Here, we report the ability of soft NPs to shrink in confined environments, therefore boosting their diffusion compared to hard, non-deformable particles. We demonstrate this behavior by embedding microgel NPs in agarose gels. The origin of the shrinking appears to be related to the overlap of the electrostatic double layers (EDL) surrounding the NPs and the agarose fibres. Indeed, it is shown that screening the EDL interactions, by increasing the ionic strength of the medium, prevents the soft particle shrinkage. The shrunken NPs diffuse up to 2 orders of magnitude faster in agarose gel than their hard NP counterparts. These findings provide valuable insights on the role of long range interactions on soft NPs dynamics in crowded environments, and help rationalize the design of more efficient NP-based transport systems.
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http://dx.doi.org/10.1038/s41467-019-12246-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754464PMC
September 2019

Synergy between Zwitterionic Polymers and Hyaluronic Acid Enhances Antifouling Performance.

Langmuir 2019 12 11;35(48):15535-15542. Epub 2019 Sep 11.

State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , P. R. China.

Challenges associated with nonspecific adsorption of proteins on sensor surfaces have steered the development of novel antifouling materials and strategies. Inspired by human synovial fluid composition and structure, we designed synergistic antifouling coatings with mixtures of hyaluronic acid (HA) and a zwitterionic bottlebrush polymer (BB). Using a fast and convenient online surface modification method, the polymers were immobilized on the Au surface, significantly increasing its hydrophilicity. Using surface plasmon resonance (SPR), a 10:1 ratio of HA to BB was found optimal to provide the best antifouling performance. Bovine serum albumin (BSA) adsorption on HA-BB coated surfaces was 0.2 ng/cm, which was 60 times lower than BB or HA alone and 25 times lower than the commonly accepted ultralow adsorption limit (<5 ng/cm), demonstrating the synergistic effect of HA and BB against nonspecific protein adsorption. This was found to be independent of BSA concentration up to physiological concentrations. Furthermore, the antifouling performance of HA-BB coated surfaces was tested against milk and serum, showing almost 92% lower protein adsorption than that on bare surfaces, suggesting the potential efficacy of this antifouling coating in real life settings.
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http://dx.doi.org/10.1021/acs.langmuir.9b01876DOI Listing
December 2019

Chitosan hydrogel micro-bio-devices with complex capillary patterns via reactive-diffusive self-assembly.

Acta Biomater 2019 11 29;99:211-219. Epub 2019 Aug 29.

Faculty of Pharmacy, Université de Montréal, Montreal, Quebec H3C 3J7, Canada. Electronic address:

We present chitosan hydrogel microfluidic devices with self-assembled complex microcapillary patterns, conveniently formed by a diffusion-reaction process. These patterns in chitosan hydrogels are formed by a single-step procedure involving diffusion of a gelation agent into the polymer solution inside a microfluidic channel. By changing the channel geometry, it is demonstrated how to control capillary length, trajectory and branching. Diffusion of nanoparticles (NPs) in the capillary network is used as a model to effectively mimic the transport of nano-objects in vascularized tissues. Gold NPs diffusion is measured locally in the hydrogel chips, and during their two-step transport through the capillaries to the gel matrix and eventually to embedded cell clusters in the gel. In addition, the quantitative analyses reported in this study provide novel opportunities for theoretical investigation of capillary formation and propagation during diffusive gelation of biopolymers. STATEMENT OF SIGNIFICANCE: Hydrogel micropatterning is a challenging task, which is of interest in several biomedical applications. Creating the patterns through self assembly is highly beneficial, because of the accessible and practical preparation procedure. In this study, we introduced complex self-assembled capillary patterns in chitosan hydrogels using a microfluidic approach. To demonstrate the potential application of these capillary patterns, a vascularized hydrogel with microwells occupied by cells was produced, and the diffusion of gold nanoparticles travelling in the capillaries and diffusing in the gel were evaluated. This model mimics a simplified biological tissue, where nanomedicine has to travel through the vasculature, extravasate into and diffuse through the extracellular matrix and eventually reach targeted cells.
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http://dx.doi.org/10.1016/j.actbio.2019.08.037DOI Listing
November 2019

Interfacial Forces across Ionic Liquid Solutions: Effects of Ion Concentration and Water Domains †.

Langmuir 2019 Dec 2;35(48):15585-15591. Epub 2019 Aug 2.

Faculty of Pharmacy , Université de Montréal , 2900 Édouard-Montpetit , Montreal H3C 3J7 , Canada.

Using the surface force apparatus (SFA), the interaction forces between mica surfaces across ionic liquid (IL) solutions are studied. The IL solution, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in propylene carbonate solvent, is used at different concentrations to elucidate the ions' conformation at the interface from the analysis of short-range structural forces. A direct correlation between the ion layer thickness at the interface and the IL molar fraction in the solution is observed, suggesting conformational changes relative to the ion packing density. In addition, effects of large microscopic and macroscopic water domains at the interface are investigated. The microscopic water domains induced significant adhesion at contact because of the long-range capillary forces, which are found to depend on solvent concentration. The macroscopic water domains entirely cover the interaction area, ensuring that the long-range interfacial interactions occur entirely across the aqueous electrolyte solution with dissolved IL ions as the electrolyte. These results help elucidate the interfacial interactions in IL-charged solid interfaces with practical importance in green energy storage, catalysis, and lubrication.
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http://dx.doi.org/10.1021/acs.langmuir.9b02011DOI Listing
December 2019

Nanoparticle heterogeneity: an emerging structural parameter influencing particle fate in biological media?

Nanoscale 2019 Jan;11(2):383-406

Centre INRS Institut Armand-Frappier, 531, boul. des Prairies, Laval, QC H7V 1B7, Canada.

Drug nanocarriers' surface chemistry is often presumed to be uniform. For instance, the polymer surface coverage and distribution of ligands on nanoparticles are described with averaged values obtained from quantification techniques based on particle populations. However, these averaged values may conceal heterogeneities at different levels, either because of the presence of particle sub-populations or because of surface inhomogeneities, such as patchy surfaces on individual particles. The characterization and quantification of chemical surface heterogeneities are tedious tasks, which are rather limited by the currently available instruments and research protocols. However, heterogeneities may contribute to some non-linear effects observed during the nanoformulation optimization process, cause problems related to nanocarrier production scale-up and correlate with unexpected biological outcomes. On the other hand, heterogeneities, while usually unintended and detrimental to nanocarrier performance, may, in some cases, be sought as adjustable properties that provide NPs with unique functionality. In this review, results and processes related to this issue are compiled, and perspectives and possible analytical developments are discussed.
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http://dx.doi.org/10.1039/c8nr04916eDOI Listing
January 2019

Biomimetic Bottlebrush Polymer Coatings for Fabrication of Ultralow Fouling Surfaces.

Angew Chem Int Ed Engl 2019 01 5;58(5):1308-1314. Epub 2018 Dec 5.

Faculty of Pharmacy, Université de Montréal, 2900 Édouard-Montpetit, Montreal, Quebec, H3C 3J7, Canada.

Demand for long-lasting antifouling surfaces has steered the development of accessible, novel, biocompatible and environmentally friendly materials. Inspired by lubricin (LUB), a component of mammalian synovial fluid with excellent antifouling properties, three block polymers offering stability, efficacy, and ease of use were designed. The bottlebrush-structured polymers adsorbed strongly on silica surfaces in less than 10 minutes by a simple drop casting or online exposure method and were extremely stable in high-salinity solutions and across a wide pH range. Antifouling properties against proteins and bacteria were evaluated with different techniques and ultralow fouling properties demonstrated. With serum albumin and lysozyme adsorption <0.2 ng cm , the polymers were 50 and 25 times more effective than LUB and known ultralow fouling coatings. The antifouling properties were also tested under MPa compression pressures by direct force measurements using surface forces apparatus. The findings suggest that these polymers are among the most robust and efficient antifouling agents currently known.
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http://dx.doi.org/10.1002/anie.201808987DOI Listing
January 2019