1
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Faiad S, Laurent Q, Prinzen AL, Asohan J, Saliba D, Toader V, Sleiman HF. Impact of the Core Chemistry of Self-Assembled Spherical Nucleic Acids on their In Vitro Fate. Angew Chem Int Ed Engl 2023; 62:e202315768. [PMID: 37905978 DOI: 10.1002/anie.202315768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
Nucleic acid therapeutics (NATs), such as mRNA, small interfering RNA or antisense oligonucleotides are extremely efficient tools to modulate gene expression and tackle otherwise undruggable diseases. Spherical nucleic acids (SNAs) can efficiently deliver small NATs to cells while protecting their payload from nucleases, and have improved biodistribution and muted immune activation. Self-assembled SNAs have emerged as nanostructures made from a single DNA-polymer conjugate with similar favorable properties as well as small molecule encapsulation. However, because they maintain their structure by non-covalent interactions, they might suffer from disassembly in biologically relevant conditions, especially with regard to their interaction with serum proteins. Here, we report a systematic study of the factors that govern the fate of self-assembled SNAs. Varying the core chemistry and using stimuli-responsive disulfide crosslinking, we show that extracellular stability upon binding with serum proteins is important for recognition by membrane receptors, triggering cellular uptake. At the same time, intracellular dissociation is required for efficient therapeutic release. Disulfide-crosslinked SNAs combine these two properties and result in efficient and non-toxic unaided gene silencing therapeutics. We anticipate these investigations will help the translation of promising self-assembled structures towards in vivo gene silencing applications.
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Affiliation(s)
- Sinan Faiad
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Quentin Laurent
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Alexander L Prinzen
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Jathavan Asohan
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Daniel Saliba
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Violeta Toader
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
| | - Hanadi F Sleiman
- Department of Chemistry, McGill University, 801 Sherbrooke St West, H3A 0B8, Montreal, Québec, Canada
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2
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Rafique MG, Remington JM, Clark F, Bai H, Toader V, Perepichka DF, Li J, Sleiman HF. Two-Dimensional Supramolecular Polymerization of DNA Amphiphiles is Driven by Sequence-Dependent DNA-Chromophore Interactions. Angew Chem Int Ed Engl 2023:e202217814. [PMID: 36939824 DOI: 10.1002/anie.202217814] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 03/21/2023]
Abstract
Two-dimensional (2D) assemblies of water-soluble block copolymers have been limited by a dearth of systematic studies that relate polymer structure to pathway mechanism and supramolecular morphology. Here, we employ sequence-defined triblock DNA amphiphiles for the supramolecular polymerization of free-standing DNA nanosheets in water. Our systematic modulation of amphiphile sequence shows the alkyl chain core forming a cell membrane-like structure and the distal π-stacking chromophore block folding back to interact with the hydrophilic DNA block on the nanosheet surface. This interaction is crucial to sheet formation, marked by a chiral 'signature', and sensitive to DNA sequence, where nanosheets form with a mixed sequence, but not with a homogenous poly(thymine) sequence. This work opens the possibility of forming well-ordered, bilayer-like assemblies using a single DNA amphiphile for applications in cell sensing, nucleic acid therapeutic delivery and enzyme arrays.
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Affiliation(s)
| | | | | | | | | | | | - Jianing Li
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, UNITED STATES
| | - Hanadi Farouk Sleiman
- McGill University, Department of Chemistry, 801 Sherbrooke St. W., H3A 0B8, Montreal, CANADA
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3
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Wong J, Toader V, Reven L. Lyotropic Nematic Phases of Isotropic Nanoparticles via Semiflexible Polymer Ligands. Macromol Rapid Commun 2023; 44:e2200951. [PMID: 36700516 DOI: 10.1002/marc.202200951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Indexed: 01/27/2023]
Abstract
Lyotropic liquid crystalline (LC) nanomaterials are normally achieved through particle shape anisotropy. Herein, it is shown that lyotropic nematic rather than cubic phases are produced from spherical nanoparticles (NPs) with semi-flexible polymer ligands. ZrO2 nanocrystals (4 nm dia.) are coated with a dense shell of poly(hexyl isocyanate) (PHIC), a helical rod-like polymer that forms lyotropic LC phases in a range of organic solvents. Solvent casted NPs with PHIC ligands above the persistence length form linear assemblies, separated by a characteristic distance related to the chain length while NPs with shorter, rigid rod PHIC ligands pack hexagonally. Concentrated NP-PHIC dispersions present nematic textures similar to the free PHIC nematic solutions but at lower critical concentrations, widening the isotropic-nematic biphasic region. 2 H NMR spectra of the NPs dispersed in a deuterated solvent display quadrupolar splittings that increase with NP concentration, showing that the PHIC ligands are magnetically aligned. The high degree of orientation order is evidence that splaying of the ligand shell transforms the spherical NPs to rod-like shapes that assemble to produce nematic lyotropic LC phases and linear NP arrays. This approach to creating anisotropic assemblies can be extended to other types of spherical NPs and semiflexible polymers.
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Affiliation(s)
- Jessie Wong
- Department of Chemistry and Centre québécois sur les matériaux fonctionnels/Quebec Centre for Advanced Materials (CQMF/QCAM), McGill University, 801 Sherbrooke St. W., Montreal, Quebec, H3A 0B8, Canada
| | - Violeta Toader
- Department of Chemistry and Centre québécois sur les matériaux fonctionnels/Quebec Centre for Advanced Materials (CQMF/QCAM), McGill University, 801 Sherbrooke St. W., Montreal, Quebec, H3A 0B8, Canada
| | - Linda Reven
- Department of Chemistry and Centre québécois sur les matériaux fonctionnels/Quebec Centre for Advanced Materials (CQMF/QCAM), McGill University, 801 Sherbrooke St. W., Montreal, Quebec, H3A 0B8, Canada
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4
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Romero Esquivel G, Toader V, Reven L, Kambhampati P. Ligand-flexible synthesis of strongly confined perovskite nanocrystals: a microwave synthetic approach. Nanoscale 2022; 14:15789-15798. [PMID: 36250330 DOI: 10.1039/d2nr04597d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Perovskite nanocrystals (PNCs) and their strongly confined versions have traditionally been synthesized via hot injection methods. However, there is a pressing need for a new synthesis method that offers more flexible surface chemistry, improved optical properties, and greater sample stability. Here we explore and exploit the recently introduced microwave (MW) synthesis method, focusing on temperature and coating ligands, including a polymer ligand for which the hot injection method is unsuitable. The optimized microwave synthetic protocols produce PNCs with better exciton definition, lower polydispersity, and stronger ligand attachment than their hot injection counterparts. A variety of characterization techniques were employed to compare the properties of PNCs produced by the hot injection versus microwave methods. Insight into the molecular basis for the improved PNC properties was provided by FTIR and several NMR experiments that revealed the nature of the attachment of different ligands and their interactions with the PNCs. The overall results demonstrate that MW synthesis is a promising alternative to the HI method, particularly if smaller PNCs with strong quantum confinement are desired.
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Affiliation(s)
| | - Violeta Toader
- Department of Chemistry, McGill University, Montreal, Canada.
| | - Linda Reven
- Department of Chemistry, McGill University, Montreal, Canada.
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5
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Zhang M, Lindner-D’Addario M, Roohnikan M, Toader V, Lennox RB, Reven L. Polymer Functionalized Nanoparticles in Blue Phase LC: Effect of Particle Shape. Nanomaterials (Basel) 2021; 12:nano12010091. [PMID: 35010041 PMCID: PMC8746361 DOI: 10.3390/nano12010091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/10/2021] [Accepted: 12/19/2021] [Indexed: 02/02/2023]
Abstract
Ethylene oxide oligomers and polymers, free and tethered to gold nanoparticles, were dispersed in blue phase liquid crystals (BPLC). Gold nanospheres (AuNPs) and nanorods (AuNRs) were functionalized with thiolated ethylene oxide ligands with molecular weights ranging from 200 to 5000 g/mol. The BPLC mixture (ΔTBP ~6 °C) was based on the mesogenic acid heterodimers, n-hexylbenzoic acid (6BA) and n-trans-butylcyclohexylcarboxylic acid (4-BCHA) with the chiral dopant (R)-2-octyl 4-[4-(hexyloxy)benzoyloxy]benzoate. The lowest molecular weight oligomer lowered and widened the BP range but adding AuNPs functionalized with the same ligand had little effect. Higher concentrations or molecular weights of the ligands, free or tethered to the AuNPs, completely destabilized the BP. Mini-AuNRs functionalized with the same ligands lowered and widened the BP temperature range with longer mini-AuNRs having a larger effect. In contrast to the AuNPs, the mini-AuNRs with the higher molecular weight ligands widened rather than destabilized the BP, though the lowest MW ligand yielded the largest BP range, (ΔTBP > 13 °C). The different effects on the BP may be due to the AuNPs accumulating at singular defect sites whereas the mini-AuNRs, with diameters smaller than that of the disclination lines, can more efficiently fill in the BP defects.
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6
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Lachance-Brais C, Hennecker CD, Alenaizan A, Luo X, Toader V, Taing M, Sherrill CD, Mittermaier AK, Sleiman HF. Tuning DNA Supramolecular Polymers by the Addition of Small, Functionalized Nucleobase Mimics. J Am Chem Soc 2021; 143:19824-19833. [PMID: 34783562 DOI: 10.1021/jacs.1c08972] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nucleobase mimicking small molecules able to reconfigure DNA are a recently discovered strategy that promises to extend the structural and functional diversity of nucleic acids. However, only simple, unfunctionalized molecules such as cyanuric acid and melamine have so far been used in this approach. In this work, we show that the addition of substituted cyanuric acid molecules can successfully program polyadenine strands to assemble into supramolecular fibers. Unlike conventional DNA nanostructure functionalization, which typically end-labels DNA strands, our approach incorporates functional groups into DNA with high density using small molecules and results in new DNA triple helices coated with alkylamine or alcohol units that grow into micrometer-long fibers. We find that small changes in the small molecule functional group can result in large structural and energetic variation in the overall assembly. A combination of circular dichroism, atomic force microscopy, molecular dynamics simulations, and a new thermodynamic method, transient equilibrium mapping, elucidated the molecular factors behind these large changes. In particular, we identify substantial DNA sugar and phosphate group deformations to accommodate a hydrogen bond between the phosphate and the small-molecule functional groups, as well as a critical chain length of the functional group which switches this interaction from intra- to interfiber. These parameters allow the controlled formation of hierarchical, hybrid DNA assemblies simply through the addition and variation of small, functionalized molecules.
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Affiliation(s)
| | - Christopher D Hennecker
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
| | - Asem Alenaizan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Xin Luo
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
| | - Violeta Toader
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
| | - Monica Taing
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
| | - C David Sherrill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Anthony K Mittermaier
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
| | - Hanadi F Sleiman
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A0B8, Canada
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7
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Dore MD, Trinh T, Zorman M, de Rochambeau D, Platnich CM, Xu P, Luo X, Remington JM, Toader V, Cosa G, Li J, Sleiman HF. Thermosetting supramolecular polymerization of compartmentalized DNA fibers with stereo sequence and length control. Chem 2021. [DOI: 10.1016/j.chempr.2021.05.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Askari MS, Lachance-Brais C, Rizzuto FJ, Toader V, Sleiman H. Remote control of charge transport and chiral induction along a DNA-metallohelicate. Nanoscale 2019; 11:11879-11884. [PMID: 31184682 DOI: 10.1039/c9nr03212f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Herein we present a new strategy to achieve chiral induction and redox switching along the backbone of metallohelicate architectures, wherein a DNA duplex directs the handedness and charge transport properties of a metal-organic assembly more than 60 bonds away (a distance of >10 nm). The quantitative and site-specific binding of copper(i) ions to DNA-templated coordination sites imparts enhanced thermodynamic stability to the assembly, while the DNA duplex transfers its natural right-handed helicity to the proximal and distal metal centers of the helicates. When copper(ii) ions are employed instead of copper(i) ions, spontaneous DNA-mediated reduction occurs, which we propose is followed by a slower change in coordination environment (from pentacoordinate CuII to tetrahedral CuI) to generate copper(i) helicates. We demonstrate that the reduction of the adjacent and distal bis-phenanthroline sites is dependent on their proximity to DNA guanine bases (which act as the electron source). The kinetics of helical charge transport can thus be tuned based on guanine-CuII separation, resulting in a sequence- and distance-dependent redox switch that transfers electronic information from DNA to multiple linearly-arranged metal centers.
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Affiliation(s)
- Mohammad S Askari
- Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, Quebec, Canada.
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9
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Guzman-Juarez B, Abdelaal A, Kim K, Toader V, Reven L. Fabrication of Amphiphilic Nanoparticles via Mixed Homopolymer Brushes and NMR Characterization of Surface Phase Separation. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01959] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brenda Guzman-Juarez
- Quebec Center for Advanced Materials (QCAM), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Ahmed Abdelaal
- Quebec Center for Advanced Materials (QCAM), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Kuenhee Kim
- Quebec Center for Advanced Materials (QCAM), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Violeta Toader
- Quebec Center for Advanced Materials (QCAM), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Linda Reven
- Quebec Center for Advanced Materials (QCAM), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
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10
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Allie S, Hegoburu I, Shin MJ, Jung JY, Toader V, Rey A, Soule ER, Reven L. Polymer functionalized nanoparticles in liquid crystals: combining PDLCs with LC nanocomposites. Soft Matter 2018; 14:8580-8589. [PMID: 30318545 DOI: 10.1039/c8sm01192c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Liquid crystal (LC)-polymer blends are important stimuli responsive materials already employed in a wide range of applications whereas nanoparticle (NP)-LC blends are an emerging class of nanocomposites. Polymer ligands offer the advantages of synthetic simplicity along with chemical and molecular weight tunability. Here we compare the phase behavior of 5CB blended with poly(ethylene oxide) (PEO) and with gold NPs functionalized with thiolated PEO (AuNP-PEO) as a function of PEO concentration by DSC, POM and 13C NMR spectroscopy. Both PEO and the AuNP-PEO form uniform dispersions in isotropic 5CB and phase separate below the I-N phase transition temperature. Above the PEO crystallization temperature, the PEO/5CB blends show the expected biphasic state of PEO rich-isotropic liquid co-existing with PEO-poor nematic droplets. At PEO concentrations above 10 wt%, nematic 5CB nucleates with PEO crystallization. Both PEO and AuNP-PEO induce homeotropic alignment of the 5CB matrix immediately below TNI. The AuNP-PEO/5CB blends form thermally reversible cellular networks similar to AuNPs functionalized with low molecular weight mesogenic ligands. A thermodynamic model to account for the observed phase behavior is presented.
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Affiliation(s)
- Safiya Allie
- Quebec Centre for Advanced Materials, Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal QC H3A 0B8, Canada.
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11
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Dionne ER, Dip C, Toader V, Badia A. Micromechanical Redox Actuation by Self-Assembled Monolayers of Ferrocenylalkanethiolates: Evens Push More Than Odds. J Am Chem Soc 2018; 140:10063-10066. [PMID: 30070479 DOI: 10.1021/jacs.8b04054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Microcantilever transducers can be valuable tools for the investigation of physicochemical processes in organized molecular films. Gold-coated cantilevers are used here to investigate the electrochemomechanics of redox-active self-assembled monolayers (SAMs) of ferrocenylalkanethiolates (Fc(CH2) nS) of different alkyl chain lengths. A significant odd-even effect is observed in the surface stress and cantilever movement generated by the oxidation of the SAM-confined ferrocenes as the number of methylene units n in the SAM backbone is varied. We demonstrate that stronger alkyl chain-chain interactions are at the origin of the larger surface stresses generated by SAMs with an even versus odd n. The findings highlight the impact of subtle structural effects and weak van der Waals interactions on the mechanical actuation produced by redox reactions in self-assembled systems.
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Affiliation(s)
- Eric R Dionne
- Département de chimie , Université de Montréal , C.P. 6128, succursale Centre-ville , Montréal , QC H3C 3J7 , Canada.,Quebec Center for Advanced Materials , FRQNT , Canada
| | - Christopher Dip
- Département de chimie , Université de Montréal , C.P. 6128, succursale Centre-ville , Montréal , QC H3C 3J7 , Canada.,Quebec Center for Advanced Materials , FRQNT , Canada
| | - Violeta Toader
- Department of Chemistry , McGill University , 801 rue Sherbrooke Ouest , Montréal , QC H3A 2K6 , Canada.,Quebec Center for Advanced Materials , FRQNT , Canada
| | - Antonella Badia
- Département de chimie , Université de Montréal , C.P. 6128, succursale Centre-ville , Montréal , QC H3C 3J7 , Canada.,Quebec Center for Advanced Materials , FRQNT , Canada
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12
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Abstract
The selective modification of individual components in a biosensor array is challenging. To address this challenge, we present a generalizable approach to selectively modify and characterize individual gold surfaces in an array, in an in situ manner. This is achieved by taking advantage of the potential dependent adsorption/desorption of surface-modified organic molecules. Control of the applied potential of the individual sensors in an array where each acts as a working electrode provides differential derivatization of the sensor surfaces. To demonstrate this concept, two different self-assembled monolayer (SAM)-forming electrochemically addressable ω-ferrocenyl alkanethiols (C11) are chemisorbed onto independent but spatially adjacent gold electrodes. The ferrocene alkanethiol does not chemisorb onto the surface when the applied potential is cathodic relative to the adsorption potential and the electrode remains underivatized. However, applying potentials that are modestly positive relative to the adsorption potential leads to extensive coverage within 10 min. The resulting SAM remains in a stable state while held at potentials <200 mV above the adsorption potential. In this state, the chemisorbed SAM does not significantly desorb nor do new ferrocenylalkythiols adsorb. Using three set applied potentials provides for controlled submonolayer alkylthiol marker coverage of each independent gold electrode. These three applied potentials are dependent upon the specifics of the respective adsorbate. Characterization of the ferrocene-modified electrodes via cyclic voltammetry demonstrates that each specific ferrocene marker is exclusively adsorbed to the desired target electrode.
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Affiliation(s)
- Ann-Lauriene Haag
- Ernest Rutherford Physics Building, Department of Physics, McGill University, 3600 Rue University, Montreal, H3A 2T8, QC, Canada
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13
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Abstract
Nanoparticle-liquid crystal (NP-LC) composites based on hydrogen bonding were explored using a model system. The ligand shells of 3 nm diameter zirconium dioxide nanoparticles (ZrO2 NPs) were varied to control their interaction with 4-n-hexylbenzoic acid (6BA). The miscibility and effect of the NPs on the nematic order as a function of particle concentration was characterized by polarized optical microscopy (POM), fluorescence microscopy and (2)H NMR spectroscopy. Nonfunctionalized ZrO2 NPs have the lowest miscibility and strongest effect on the LC matrix due to irreversible binding of 6BA to the NPs via a strong zirconium carboxylate bond. The ZrO2 NPs were functionalized with 6-phosphonohexanoic acid (6PHA) or 4-(6-phosphonohexyloxy)benzoic acid (6BPHA) which selectively bind to the ZrO2 NP surface via the phosphonic acid groups. The miscibility was increased by controlling the concentration of the pendant CO2H groups by adding hexylphosphonic acid (HPA) to act as a spacer group. Fluorescence microscopy of lanthanide doped ZrO2 NPs showed no aggregates in the nematic phase below the NP concentration where aggregates are observed in the isotropic phase. The functionalized NPs preferably concentrate into LC defects and any remaining isotropic liquid but are still present throughout the nematic liquid at a lower concentration.
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Affiliation(s)
- Mahdi Roohnikan
- Department of Chemistry, Centre for Self-Assembled Chemical Structures (CSACS) , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
- Department of Chemical Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada
| | - Violeta Toader
- Department of Chemistry, Centre for Self-Assembled Chemical Structures (CSACS) , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Alejandro Rey
- Department of Chemical Engineering, McGill University , Montreal, Quebec H3A 0C5, Canada
| | - Linda Reven
- Department of Chemistry, Centre for Self-Assembled Chemical Structures (CSACS) , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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14
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Alazaroaie S, Catanescu CO, Pavel D, Scutaru D, Romanic M, Toader V, Simionescu CI, Hurduc N. Liquid Crystalline Polymers. 15. Synthesis and Thermal Behavior of Some Aromatic Polyethers Containing Different Spacers. HIGH PERFORM POLYM 2016. [DOI: 10.1177/0954008305043735] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A series of aromatic homo- and copolyethers containing 6, 7 or 8 methylenic groups as spacers are presented. The polymers were synthesized by phase-transfer catalysis and they were characterized by using 1H-NMR, polarized light microscopy, differential scanning calorimetry and thermogravimetric analyses. All copolymers have low molecular weight, situated within the oligomer domain. They have high transition temperatures except for the case when bent or semi-flexible bisphenols were used as comonomers. Only 4,4 -dihydroxyazobenzene-based polymers showed liquid crystalline properties with a mesophase range over 50° C, and with the clearing temperatures situated near their thermal decomposition limit. The insertion of kink or flexible bisphenols was not favorable to mesophase formation (it induced too high a disorder in the system), but it lowered the transition temperatures, as expected. Few exceptions occurred in the case of bisphenol A and 4,4 -dihydroxybenzophenone. The biphasic nature of these copolyethers is most probably due to both the polydispersity and the chemical heterogeneity of the samples. Some of the semi-crystalline copolymers may exhibit virtual mesophase that can be uncovered by increasing their molecular weight or by raising the free energy of the isotropic liquid state.
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Affiliation(s)
| | - Carmen Otilia Catanescu
- “Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, 700487 Iasi, Romania
| | - Dumitru Pavel
- Department of Applied Chemistry, RMIT University, GPO box 2476 V, Melbourne, Vic. 3001, Australia
| | | | - Mihaela Romanic
- Technical University Iasi, Faculty of Chemical Engineering, Department of Organic Chemistry, Bd. Mangeron 71, 700050 Iasi, Romania
| | | | - Cristofor I. Simionescu
- Technical University Iasi, Faculty of Chemical Engineering, Department of Macromolecules, Bd. Mangeron 71, 700050 Iasi, Romania
| | - Nicolae Hurduc
- Technical University Iasi, Faculty of Chemical Engineering, Department of Macromolecules, Bd. Mangeron 71, 700050 Iasi, Romania
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15
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Gharbi MA, Manet S, Lhermitte J, Brown S, Milette J, Toader V, Sutton M, Reven L. Reversible Nanoparticle Cubic Lattices in Blue Phase Liquid Crystals. ACS Nano 2016; 10:3410-5. [PMID: 26900753 DOI: 10.1021/acsnano.5b07379] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Blue phases (BPs), a distinct class of liquid crystals (LCs) with 3D periodic ordering of double twist cylinders involving orthogonal helical director twists, have been theoretically studied as potential templates for tunable colloidal crystals. Here, we report the spontaneous formation of thermally reversible, cubic crystal nanoparticle (NP) assemblies in BPs. Gold NPs, functionalized to be highly miscible in cyanobiphenyl-based LCs, were dispersed in BP mixtures and characterized by polarized optical microscopy and synchrotron small-angle X-ray scattering (SAXS). The NPs assemble by selectively migrating to periodic strong trapping sites in the BP disclination lines. The NP lattice, remarkably robust given the small particle size (4.5 nm diameter), is commensurate with that of the BP matrix. At the BP I to BP II phase transition, the NP lattice reversibly switches between two different cubic structures. The simultaneous presence of two different symmetries in a single material presents an interesting opportunity to develop novel dynamic optical materials.
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Affiliation(s)
- Mohamed Amine Gharbi
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
- Department of Physics, McGill University , Montreal, Québec H3A2T8, Canada
| | - Sabine Manet
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
- Department of Physics, McGill University , Montreal, Québec H3A2T8, Canada
| | - Julien Lhermitte
- Department of Physics, McGill University , Montreal, Québec H3A2T8, Canada
| | - Sarah Brown
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
- Department of Physics, McGill University , Montreal, Québec H3A2T8, Canada
| | - Jonathan Milette
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
| | - Violeta Toader
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
| | - Mark Sutton
- Department of Physics, McGill University , Montreal, Québec H3A2T8, Canada
| | - Linda Reven
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University , Montreal, Québec H3A0B8, Canada
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16
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Avakyan N, Greschner AA, Aldaye F, Serpell CJ, Toader V, Petitjean A, Sleiman HF. Reprogramming the assembly of unmodified DNA with a small molecule. Nat Chem 2016; 8:368-76. [PMID: 27001733 DOI: 10.1038/nchem.2451] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 01/07/2016] [Indexed: 02/08/2023]
Abstract
The ability of DNA to store and encode information arises from base pairing of the four-letter nucleobase code to form a double helix. Expanding this DNA 'alphabet' by synthetic incorporation of new bases can introduce new functionalities and enable the formation of novel nucleic acid structures. However, reprogramming the self-assembly of existing nucleobases presents an alternative route to expand the structural space and functionality of nucleic acids. Here we report the discovery that a small molecule, cyanuric acid, with three thymine-like faces, reprogrammes the assembly of unmodified poly(adenine) (poly(A)) into stable, long and abundant fibres with a unique internal structure. Poly(A) DNA, RNA and peptide nucleic acid (PNA) all form these assemblies. Our studies are consistent with the association of adenine and cyanuric acid units into a hexameric rosette, which brings together poly(A) triplexes with a subsequent cooperative polymerization. Fundamentally, this study shows that small hydrogen-bonding molecules can be used to induce the assembly of nucleic acids in water, which leads to new structures from inexpensive and readily available materials.
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Affiliation(s)
- Nicole Avakyan
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Andrea A Greschner
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.,INRS: Centre Énergie Matériaux Télécommunications, 1650 Boul. Lionel-Boulet, Varennes Quebec J3X 1S2, Canada
| | - Faisal Aldaye
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Christopher J Serpell
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.,School of Physical Sciences, Ingram Building, University of Kent, Canterbury CT2 7NH, Kent, UK
| | - Violeta Toader
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Anne Petitjean
- Department of Chemistry, Queen's University, Chernoff Hall, 90 Bader Lane, Kingston Ontario K7L 3N6, Canada
| | - Hanadi F Sleiman
- Department of Chemistry and Centre for Self-assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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17
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Leonardi A, Puig J, Antonacci J, Arenas G, Zucchi I, Hoppe C, Reven L, Zhu L, Toader V, Williams R. Remote activation by green-light irradiation of shape memory epoxies containing gold nanoparticles. Eur Polym J 2015. [DOI: 10.1016/j.eurpolymj.2015.08.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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18
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Dauphin-Ducharme P, Rosati F, Greschner A, De Bruijn AD, Salvatore D, Toader V, Lau KL, Mauzeroll J, Sleiman H. Modulation of charge transport across double-stranded DNA by the site-specific incorporation of copper bis-phenanthroline complexes. Langmuir 2015; 31:1850-1854. [PMID: 25590949 DOI: 10.1021/la504300g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The site-specific incorporation of transition-metal complexes within DNA duplexes, followed by their immobilization on a gold surface, was studied by electrochemistry to characterize their ability to mediate charge. Cyclic voltammetry, square-wave voltammetry, and control experiments were carried out on fully matched and mismatched DNA strands that are mono- or bis-labeled with transition-metal complexes. These experiments are all consistent with the ability of the metal centers to act as a redox probe that is well coupled to the DNA π-stack, allowing DNA-mediated charge transport.
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Affiliation(s)
- Philippe Dauphin-Ducharme
- Department of Chemistry, McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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19
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Ban SR, Wang HN, Toader V, Bohle DS, Li CJ. Switching the Z/E Selectivity in the Palladium(II)-Catalyzed Decarboxylative Heck Arylations of trans-Cinnamaldehydes by Solvent. Org Lett 2014; 16:6282-5. [DOI: 10.1021/ol502955r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Shu-Rong Ban
- Department
of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
- School
of Pharmaceutical Science, Shanxi Medical University, Taiyuan 030001, People’s Republic of China
| | - Hai-Ning Wang
- Department
of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Violeta Toader
- Department
of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - D. Scott Bohle
- Department
of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Chao-Jun Li
- Department
of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
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20
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Affiliation(s)
- Blythe Fortier-McGill
- Centre
for Self-Assembled
Chemical Structures (CSACS-CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Violeta Toader
- Centre
for Self-Assembled
Chemical Structures (CSACS-CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
| | - Linda Reven
- Centre
for Self-Assembled
Chemical Structures (CSACS-CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H3A 0B8, Canada
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21
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Abstract
The redox-activated deflection of microcantilevers has attracted interest for nanoactuation and chemical sensing. Microcantilever sensors are devices that transduce (bio)chemical reactions into a quantifiable nanomechanical motion via surface stress changes. Despite promising applications in analytical science, poor signal-to-noise ratios and a limited understanding of the molecular origins of the surface stress changes that cause the observed deflections remain obstacles to cantilever-based sensing becoming an established (bio)detection method, such as surface plasmon resonance and electrochemistry. We use phase-separated, binary self-assembled monolayers (SAMs) of ferrocenyldodecanethiolate and n-undecanethiolate as a model system to study the effect of the steric crowding of the redox centers on the surface stress change and cantilever deflection produced by the electrochemical oxidation of the surface-tethered ferrocene to ferrocenium. We correlate the measured surface stress change to the fraction of the clustered ferrocenyldodecanethiolate phase in the binary SAMs. The pairing of anions with the sterically crowded clustered ferroceniums induces a collective molecular reorientation which drives the cantilever deflection. The results provide fundamental insights into the response mechanism of microcantilever-based actuating and sensing technologies.
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Affiliation(s)
- Eric R Dionne
- Department of Chemistry, Centre for Self-Assembled Chemical Structures of the Fonds de recherche du Québec - Nature et technologies, Université de Montréal , C.P. 6128 succursale Centre-ville, Montréal, QC H3C 3J7, Canada
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22
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Dionne ER, Sultana T, Norman LL, Toader V, Badia A. Redox-Induced Ion Pairing of Anionic Surfactants with Ferrocene-Terminated Self-Assembled Monolayers: Faradaic Electrochemistry and Surfactant Aggregation at the Monolayer/Liquid Interface. J Am Chem Soc 2013; 135:17457-68. [DOI: 10.1021/ja408512q] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Eric R. Dionne
- Department of Chemistry,
Centre for Self-Assembled Chemical Structures of the Fonds de recherche
du Québec-Nature et technologies, Université de Montréal, C.P 6128 succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada
| | - Tania Sultana
- Department of Chemistry,
Centre for Self-Assembled Chemical Structures of the Fonds de recherche
du Québec-Nature et technologies, Université de Montréal, C.P 6128 succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada
| | - Lana L. Norman
- Department of Chemistry,
Centre for Self-Assembled Chemical Structures of the Fonds de recherche
du Québec-Nature et technologies, Université de Montréal, C.P 6128 succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada
| | - Violeta Toader
- Department of Chemistry,
Centre for Self-Assembled Chemical Structures of the Fonds de recherche
du Québec-Nature et technologies, Université de Montréal, C.P 6128 succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada
| | - Antonella Badia
- Department of Chemistry,
Centre for Self-Assembled Chemical Structures of the Fonds de recherche
du Québec-Nature et technologies, Université de Montréal, C.P 6128 succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada
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23
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Milette J, Toader V, Soulé ER, Lennox RB, Rey AD, Reven L. A molecular and thermodynamic view of the assembly of gold nanoparticles in nematic liquid crystal. Langmuir 2013; 29:1258-1263. [PMID: 23294352 DOI: 10.1021/la304189n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The molecular interactions driving the assembly of gold nanoparticles (AuNPs) in a nematic liquid crystal (LC) are directly detected by nuclear magnetic resonance (NMR) spectroscopy and thermodynamically analyzed. The orientational orders of the selectively deuterated LC matrix and AuNP ligands, each separately followed by variable temperature (2)H NMR as a function of particle concentration, were observed to be strongly correlated. The mechanism of the reversible formation of long-range, quasi-periodic nanoparticle structures is attributed to the coupling of the AuNP ligands to the LC matrix, inducing an isotropic-nematic biphasic state. Experimentally validated thermodynamic modeling shows that, in contrast to colloidal nematics that are dominated by elastic forces, nematic dispersions of nanoparticles self-organize through a subtle balance of entropic forces and excluded volume, interface-mediated mesogen and nanoparticle molecular interactions, and couplings between conserved and nonconserved order parameters. Fine-tuning of these interactions through ligand and mesogen chemistry, together with mesoscale modeling, provides a route for materials innovations by merging structured fluid physics and nanoscience.
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Affiliation(s)
- Jonathan Milette
- Centre for Self-assembled Chemical Structures, Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, QC H4A 3B7, Canada
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24
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Greschner AA, Toader V, Sleiman HF. The Role of Organic Linkers in Directing DNA Self-Assembly and Significantly Stabilizing DNA Duplexes. J Am Chem Soc 2012; 134:14382-9. [PMID: 22873572 DOI: 10.1021/ja3033197] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrea A. Greschner
- Department of Chemistry and Center for Self-Assembled
Chemical Structures (CSACS), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Violeta Toader
- Department of Chemistry and Center for Self-Assembled
Chemical Structures (CSACS), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Hanadi F. Sleiman
- Department of Chemistry and Center for Self-Assembled
Chemical Structures (CSACS), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
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25
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Affiliation(s)
- Blythe Fortier-McGill
- Centre for Self-Assembled Chemical Structures (CSACS-CRMAA),
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8 Canada
| | - Violeta Toader
- Centre for Self-Assembled Chemical Structures (CSACS-CRMAA),
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8 Canada
| | - Linda Reven
- Centre for Self-Assembled Chemical Structures (CSACS-CRMAA),
Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8 Canada
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26
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Affiliation(s)
- Blythe Fortier-McGill
- Center for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, Canada H3A 2K6
| | - Violeta Toader
- Center for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, Canada H3A 2K6
| | - Linda Reven
- Center for Self-Assembled Chemical Structures (CSACS/CRMAA), Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, Canada H3A 2K6
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27
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Milette J, Toader V, Reven L, Lennox RB. Tuning the miscibility of gold nanoparticles dispersed in liquid crystals via the thiol-for-DMAP reaction. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm10553a] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Hagos GK, Carroll RE, Kouznetsova T, Li Q, Toader V, Fernandez PA, Swanson SM, Thatcher GRJ. Colon cancer chemoprevention by a novel NO chimera that shows anti-inflammatory and antiproliferative activity in vitro and in vivo. Mol Cancer Ther 2007; 6:2230-9. [PMID: 17699720 DOI: 10.1158/1535-7163.mct-07-0069] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chemopreventive agents in colorectal cancer possess either antiproliferative or anti-inflammatory actions. Nonsteroidal anti-inflammatory drugs (NSAID) and cyclooxygenase-2 inhibitors have shown promise, but are compromised by side effects. Nitric oxide donor NSAIDs are organic nitrates conjugated via a labile linker to an NSAID, originally designed for use in pain relief, that have shown efficacy in colorectal cancer chemoprevention. The NO chimera, GT-094, is a novel nitrate containing an NSAID and disulfide pharmacophores, a lead compound for the design of agents specifically for colorectal cancer. GT-094 is the first nitrate reported to reduce aberrant crypt foci (by 45%) when administered after carcinogen in the standard azoxymethane rat model of colorectal cancer. Analysis of proximal and distal colon tissue from 8- and 28-week rat/azoxymethane studies showed that GT-094 treatment reduced colon crypt proliferation by 30% to 69%, reduced inducible NO synthase (iNOS) levels by 33% to 67%, reduced poly(ADP-ribose)polymerase-1 expression and cleavage 2- to 4-fold, and elevated levels of p27 in the distal colon 3-fold. Studies in cancer cell cultures recapitulated actions of GT-094: antiproliferative activity and transient G(2)-M phase cell cycle block were measured in Caco-2 cells; apoptotic activity was examined but not observed; anti-inflammatory activity was seen in the inhibition of up-regulation of iNOS and endogenous NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells. In summary, antiproliferative, anti-inflammatory, and cytoprotective activity observed in vivo and in vitro support GT-094 as a lead compound for the design of NO chimeras for colorectal cancer chemoprevention.
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Affiliation(s)
- Ghenet K Hagos
- Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S Wood Street, Chicago, IL 60612, USA
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29
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Abstract
The paper presents a non-isothermal kinetic study of the degradation process of some aromatic copolyethers containing a tetra-methylenic spacer. The polymers were synthesized using the phase transfer catalysis technique, starting from 1,4-dichlorobutane and various bisphenols (4,4'-dihidroxyazobenzene, 4,4'-dihydroxydiphenyl, bisphenol A and 2,7-dihydroxynaphthlene). Dynamic thermal analysis methods such as ATG, DTG and ATD were used. In order to work out the basic kinetic parameters and the reliance between activation energy and conversion degree, differential methods based on the `order reaction model' were applied and standard kinetic models were also used. The thermostability of the good samples up to 320°C was demonstrated. The degradation mechanism took place by successive reactions, controlled by a nucleation process influenced by the polymer molecular structure.
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Affiliation(s)
- Nicolae Hurduc
- Gh. Asachi' Technical University Iasi, Faculty of Chemical Engineering, B-dul D. Mangeron 71, Iasi-700050, Romania
| | - Gabriela Lisa
- Gh. Asachi' Technical University Iasi, Faculty of Chemical Engineering, B-dul D. Mangeron 71, Iasi-700050, Romania, or
| | - Cristina Damian
- Al. I. Cuza' University Iasi, Faculty of Chemistry, B-dul Carol I, No. 11, 700506 Iasi, Romania
| | - Violeta Toader
- Department of Pharmacology & Toxicology, Queen's University, Kingston K7L 3N6, Canada
| | - Natalia Hurduc
- Al. I. Cuza' University Iasi, Faculty of Chemistry, B-dul Carol I, No. 11, 700506 Iasi, Romania
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30
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Abstract
Ring-opening metathesis polymerization was used to generate an ABC triblock copolymer, containing complementary diamidopyridine (DAP) and thymine (THY) outer blocks, which assembles into spherical aggregates held together by DAP-THY noncovalent interactions. Addition of THY-containing small guest molecules results in complete opening and deaggregation of the block copolymer micelle. This molecular recognition and macroscopic response shows high selectivity to the guest structure, and tolerates only a small amount of conformational mobility in the THY guest. On the other hand, addition of a small DAP-containing guest does not break the aggregates, but instead, results in new micelles which show a different selectivity profile from the parent morphology. We have examined the effect of a number of structural features in the block copolymers, on both the extent and selectivity of their macroscopic response to guests (that is, opening of the micelle). This study has resulted in a set of structural guidelines, which help in the design of effective molecule-responsive micelles for applications in selective drug delivery, sensing, and surface patterning.
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Affiliation(s)
- Yoshihiro Ishihara
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada
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31
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Rakotondradany F, Palmer A, Toader V, Chen B, Whitehead MA, Sleiman HF. Hydrogen-bond self-assembly of DNA-analogues into hexameric rosettes. Chem Commun (Camb) 2005:5441-3. [PMID: 16261240 DOI: 10.1039/b511984g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-assembly of a DNA-analogue hexameric rosette from triaminopyrimidine and cyanuric acid-based nucleosides, and its subsequent aggregation into rod-like morphologies is reported.
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32
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Thatcher GRJ, Nicolescu AC, Bennett BM, Toader V. Nitrates and NO release: contemporary aspects in biological and medicinal chemistry. Free Radic Biol Med 2004; 37:1122-43. [PMID: 15451053 DOI: 10.1016/j.freeradbiomed.2004.06.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Accepted: 06/03/2004] [Indexed: 11/28/2022]
Abstract
Nitroglycerine has been used clinically in the treatment of angina for 130 years, yet important details on the mechanism of action, biotransformation, and the associated phenomenon of nitrate tolerance remain unanswered. The biological activity of organic nitrates can be said to be nitric oxide mimetic, leading to recent, exciting progress in realizing the therapeutic potential of nitrates. Unequivocally, nitroglycerine and most other organic nitrates, including NO-NSAIDs, do not behave as NO donors in the most fundamental action: in vitro activation of sGC to produce cGMP. The question as to whether the biological activity of nitrates results primarily or exclusively from NO donation will not be satisfactorily answered until the location, the apparatus, and the mechanism of reduction of nitrates to NO are defined. Similarly, the therapeutic potential of nitrates will not be unlocked until this knowledge is attained. Aspects of the therapeutic and biological activity of nitrates are reviewed in the context of the chemistry of nitrates and the elusive efficient 3e- reduction required to generate NO.
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Affiliation(s)
- Gregory R J Thatcher
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood Street, Chicago, IL 60612-7231, USA.
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33
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Toader V, Xu X, Nicolescu A, Yu L, Bolton JL, Thatcher GRJ. Nitrosation, Nitration, and Autoxidation of the Selective Estrogen Receptor Modulator Raloxifene by Nitric Oxide, Peroxynitrite, and Reactive Nitrogen/Oxygen Species. Chem Res Toxicol 2003; 16:1264-76. [PMID: 14565768 DOI: 10.1021/tx025641h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The regulation of estrogenic and antiestrogenic effects by selective estrogen receptor modulators (SERMs) provides the basis for use in long-term therapy in cancer chemoprevention and postmenopausal osteoporosis. However, the evidence for carcinogenic properties within this class requires study of potential pathways of toxicity. There is strong evidence for the elevation of cellular levels of NO in tissue treated with SERMs, including the benzothiophene derivative, raloxifene, in part via up-regulation of nitric oxide synthases. Therefore, the reactions of 17beta-estradiol (E(2)), raloxifene, and an isomer with NO, peroxynitrite, and reactive nitrogen/oxygen species (RNOS) generated from NO(2)(-)/H(2)O(2) systems were examined. Peroxynitrite from bolus injection or slow release from higher concentrations of 3-morpholinosydnonimine (SIN-1) reacted with the benzothiophenes and E(2) to give aromatic ring nitration, whereas peroxynitrite, produced from the slow decomposition of lower concentrations of SIN-1, was relatively unreactive toward E(2) and yielded oxidation and nitrosation products with raloxifene and its isomer. The oxidation and nitrosation products formed were characterized as a dimer and quinone oxime derivative. Interestingly, the reaction of the benzothiophenes with NO in aerobic solution efficiently generated the same oxidation products. Stable quinone oximes are not unprecedented but have not been previously reported as products of RNOS-mediated metabolism. The reaction of glutathione (GSH) with the quinone oxime gave both GSH adducts from Michael addition and reduction to the corresponding o-aminophenol. The ready autoxidation of raloxifene, observed in the presence of NO, is the first such observation on the reactivity of SERMs and is potentially a general phenomenon of significance to SERM chemical toxicology.
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Affiliation(s)
- Violeta Toader
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 Wood Street, Chicago, Illinois 60612-7231, USA
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34
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Abstract
There is increasing evidence that S-nitrosylation is a mechanism for the regulation of protein function via the modification of critical sulfhydryl groups. The activity of rat liver microsomal glutathione S-transferase (GST) is increased after treatment with N-ethylmaleimide (NEM), a sulfhydryl alkylating reagent, and is also increased under conditions of oxidative stress. In the present study, preincubation of purified rat liver microsomal GST with S-nitrosoglutathione (GSNO) or the nitric oxide (NO) donor, 1,1-diethyl-2-hydroxy-2-nitrosohydrazine (DEA/NO), resulted in a 2-fold increase in enzyme activity. This increase in activity was reversed by dithiothreitol. The initial treatment of microsomal GST with either GSNO or DEA/NO was associated with an 85% loss of free sulfhydryl groups. After removal of the nitrosylating agents over a 6-hr period, approximately 50% of the enzyme was still nitrosylated, as determined by redox chemiluminescence. Furthermore, preincubation of either purified enzyme or hepatic microsomes with GSNO or DEA/NO prevented further enzyme activation by NEM, suggesting that NEM and the NO donors interact with a common population of sulfhydryl groups in the enzyme. In contrast, both NEM and NO donors partially inhibited the activity of cytosolic GST isoforms. The inhibitory activity of NEM and NO donors was much more evident when the GST pi isoform was used instead of a mixture of GST isoforms. These data suggest that there may be differential regulation of microsomal and cytosolic GST activities under conditions of nitrosative stress.
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Affiliation(s)
- Yanbin Ji
- Department of Pharmacology and Toxicology, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6
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35
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Artz JD, Toader V, Zavorin SI, Bennett BM, Thatcher GR. In vitro activation of soluble guanylyl cyclase and nitric oxide release: a comparison of NO donors and NO mimetics. Biochemistry 2001; 40:9256-64. [PMID: 11478893 DOI: 10.1021/bi002885x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitric oxide (NO) performs a central role in biological systems, binding to the heme site of soluble guanylyl cyclase (sGC), leading to enzyme activation and elevation of intracellular levels of cGMP. Organic nitrates, in particular, nitroglycerin (GTN), are clinically important nitrovasodilators that function as NO-mimetics in biological systems. Comparison of sGC activation data with electrochemically measured rates of NO release for genuine NO donors, NONOates and nitrosothiols, yields an excellent correlation between the EC(50) for sGC activation and the rate constant for NO release, k(NO). However, activation of sGC by GTN and the nitrates has very different characteristics, including the requirement for specific added thiols, for example, cysteine. The reaction of GTN with cysteine in anaerobic solution yields NO slowly, and NO release, measured by chemiluminescence detection, is quenched by added metal ion chelator. The generation of NO under aerobic conditions is 100-fold slower than the anaerobic reaction. Furthermore, NO release from the reaction of GTN with cysteine in phosphate buffer is too slow to account for sGC activation by GTN/cysteine. The slow rate of the chemical reaction to release NO suggests that nitrates can activate sGC by an NO-independent mechanism. In contrast to the genuine NO donors, GTN behaves as a partial agonist with respect to sGC activation, but in the presence of the allosteric sGC activator, YC-1, GTN exhibits full agonist activity.
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Affiliation(s)
- J D Artz
- Department of Chemistry, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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Toader V, Cosgarea M. [Effectiveness and potentials of specific hyposensitizing treatment for allergic rhinitis in children]. Rev Chir Oncol Radiol O R L Oftalmol Stomatol Otorinolaringol 1985; 30:81-8. [PMID: 3161145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
MESH Headings
- Adolescent
- Child
- Child, Preschool
- Desensitization, Immunologic/methods
- Female
- Humans
- Male
- Rhinitis, Allergic, Perennial/prevention & control
- Rhinitis, Allergic, Perennial/therapy
- Rhinitis, Allergic, Seasonal/prevention & control
- Rhinitis, Allergic, Seasonal/therapy
- Time Factors
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Mihalca E, Toader V, Bogdan D. [Iatrogenic hypercalcemia]. Pediatria (Bucur) 1973; 22:445-52. [PMID: 4790543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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