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- Keyword
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- Molecular Dynamics Simulation (4)
- Electrospray Ionization (3)
- Mass (3)
- Protein Conformation (3)
- Spectrometry (3)
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- Spectrometry, Mass, Electrospray Ionization (3)
- Escherichia coli (2)
- Ligands (2)
- Myoglobin (2)
- Protein Unfolding (2)
- Algorithms (1)
- Alzheimer’s disease (1)
- Amino resin (1)
- Amyloid beta-derived diffusible ligand (ADDL) (1)
- Animals (1)
- Anti-Bacterial Agents (1)
- Apoproteins (1)
- Cations (1)
- Cations, Monovalent (1)
- Chemical (1)
- Coordination chemistry (1)
- Crown Ethers (1)
- Depolymerization (1)
- Deuterium Exchange Measurement (1)
- Electrochemiluminescence (1)
- Electrochemistry (1)
- Embryonic rat cortical neurons (1)
- Encapsulation (1)
- Formazanate (1)
- Gold nanoparticle (1)
Articles 1 - 30 of 30
Full-Text Articles in Physical Sciences and Mathematics
Advancements In Fractal Plasmonics: Structures, Optical Properties, And Applications., Gregory Q Wallace, Francois Lagugne-Labarthet
Advancements In Fractal Plasmonics: Structures, Optical Properties, And Applications., Gregory Q Wallace, Francois Lagugne-Labarthet
Chemistry Publications
The structural characteristics of plasmonic nanostructures directly influence their plasmonic properties, and therefore, their potential role in applications ranging from sensing and catalysis to light- and energy-harvesting. For a structure to be compatible with a selected application, it is critical to accurately tune the plasmonic properties over a specific spectral range. Fabricating structures that meet these stringent requirements remains a significant challenge as plasmon resonances are generally narrow with respect to the considered selected spectral range. Adapted from their well-established role in GHz applications, plasmonic fractal structures have emerged as architectures of interest due to their ability to support multiple …
Near-Infrared Photoluminescence And Electrochemiluminescence From An Exceptionally Simple Boron Difluoride Formazanate Dye, Ryan R. Maar, Ruizhong Zhang, David G. Stephens, Zhifeng Ding, Joe Gilroy
Near-Infrared Photoluminescence And Electrochemiluminescence From An Exceptionally Simple Boron Difluoride Formazanate Dye, Ryan R. Maar, Ruizhong Zhang, David G. Stephens, Zhifeng Ding, Joe Gilroy
Chemistry Publications
Electrochemiluminescence involves the generation of light via electrochemical reactions and has recently shown utility for single-cell imaging. To further develop this novel imaging platform, it is necessary to produce readily available dyes that photoluminesce and electrochemiluminesce in the near-infrared region to limit absorption by biological tissue. To address this need, we prepared a boron difluoride formazanate dye that exhibits near-infrared photoluminescence and electrochemiluminescence in two straightforward synthetic steps. Examination of its solid-state structure suggests that the N-aryl substituents have significant quinoidal character, which narrows the S1-S0 energy gap and leads to near-infrared absorption and photoluminescence. Electrochemical …
Evidence For A Partially Stalled Γ Rotor In F, Angela Murcia Rios, Siavash Vahidi, Stanley D Dunn, Lars Konermann
Evidence For A Partially Stalled Γ Rotor In F, Angela Murcia Rios, Siavash Vahidi, Stanley D Dunn, Lars Konermann
Chemistry Publications
F1-ATPase uses ATP hydrolysis to drive rotation of the γ subunit. The γ C-terminal helix constitutes the rotor tip that is seated in an apical bearing formed by α3β3. It remains uncertain to what extent the γ conformation during rotation differs from that seen in rigid crystal structures. Existing models assume that the entire γ subunit participates in every rotation. Here we interrogated E. coli F1-ATPase by hydrogen-deuterium exchange (HDX) mass spectrometry. Rotation of γ caused greatly enhanced deuteration in the γ C-terminal helix. The HDX kinetics implied that most F1 …
Phosphonium Hydrogels For Controlled Release Of Ionic Cargo., Tristan D Harrison, Paul J Ragogna, Elizabeth R Gillies
Phosphonium Hydrogels For Controlled Release Of Ionic Cargo., Tristan D Harrison, Paul J Ragogna, Elizabeth R Gillies
Chemistry Publications
We describe the synthesis of three different phosphonium salts and their reaction with poly(ethylene glycol) dimethacrylate to create cationic hydrogels. The hydrogels were loaded with an anionic dye and an anionic anti-inflammatory drug through ionic interactions and compared with an analogous ammonium gel. The release rates of these anions depended on their structure and pKa values, as well as the pH and ionic strength of the release medium.
Surprising Antibacterial Activity And Selectivity Of Hydrophilic Polyphosphoniums Featuring Sugar And Hydroxy Substituents., Tyler J Cuthbert, Benjamin Hisey, Tristan D Harrison, John F Trant, Elizabeth R Gillies, Paul J Ragogna
Surprising Antibacterial Activity And Selectivity Of Hydrophilic Polyphosphoniums Featuring Sugar And Hydroxy Substituents., Tyler J Cuthbert, Benjamin Hisey, Tristan D Harrison, John F Trant, Elizabeth R Gillies, Paul J Ragogna
Chemistry Publications
There is currently an urgent need for the development of new antibacterial agents to combat the spread of antibiotic-resistant bacteria. We explored the synthesis and antibacterial activities of novel, sugar-functionalized phosphonium polymers. While these compounds exhibited antibacterial activity, we unexpectedly found that the control polymer poly(tris(hydroxypropyl)vinylbenzylphosphonium chloride) showed very high activity against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and very low haemolytic activity against red blood cells. These results challenge the conventional wisdom in the field that lipophilic alkyl substituents are required for high antibacterial activity and opens prospects for new classes of antibacterial polymers.
Multi-Stimuli-Responsive Self-Immolative Polymer Assemblies, Rebecca E. Yardley, Elizabeth R. Gillies
Multi-Stimuli-Responsive Self-Immolative Polymer Assemblies, Rebecca E. Yardley, Elizabeth R. Gillies
Chemistry Publications
Self-immolative polymers (SIPs) undergo depolymerization in response to the cleavage of stimuli-responsive end-caps from their termini. Some classes of SIPs, including polycarbamates, have depolymerization rates that depend on environmental factors such as solvent and pH. In previous work, hydrophobic SIPs have been incorporated into amphiphilic block copolymers and used to prepare nanoassemblies. However, stimuli-responsive hydrophilic blocks have not previously been incorporated. In the current work, we synthesized amphiphilic copolymers composed of a hydrophobic polycarbamate SIP block and a hydrophilic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) block connected by a UV light-responsive linker end-cap. It was hypothesized that after assembly of the block copolymers …
Electrospray Ionization Of Polypropylene Glycol: Rayleigh-Charged Droplets, Competing Pathways, And Charge State-Dependent Conformations., Quentin Duez, Haidy Metwally, Lars Konermann
Electrospray Ionization Of Polypropylene Glycol: Rayleigh-Charged Droplets, Competing Pathways, And Charge State-Dependent Conformations., Quentin Duez, Haidy Metwally, Lars Konermann
Chemistry Publications
Recent molecular dynamics (MD) simulations from various laboratories have advanced the general understanding of electrospray ionization (ESI)-related processes. Unfortunately, computational cost has limited most of those previous endeavors to ESI droplets with radii of ∼3 nm or less, which represent the low end of the size distribution in the ESI plume. The current work extends this range by conducting simulations on aqueous ESI droplets with radii of 5.5 nm (∼23 000 water molecules). Considering that computational cost increases with r6, this is a significant step forward. We focused on the ESI process for polypropylene glycol (PPG) which is …
Chain Ejection Model For Electrospray Ionization Of Unfolded Proteins: Evidence From Atomistic Simulations And Ion Mobility Spectrometry., Haidy Metwally, Quentin Duez, Lars Konermann
Chain Ejection Model For Electrospray Ionization Of Unfolded Proteins: Evidence From Atomistic Simulations And Ion Mobility Spectrometry., Haidy Metwally, Quentin Duez, Lars Konermann
Chemistry Publications
The ion evaporation model (IEM) and the charged residue model (CRM) represent cornerstones of any discussion related to the mechanism of electrospray ionization (ESI). Molecular dynamics (MD) simulations have confirmed that small ions such as Na+ are ejected from the surface of aqueous ESI droplets (IEM), while folded proteins in native ESI are released by water evaporation to dryness (CRM). ESI of unfolded proteins yields [M + zH] z+ ions that are much more highly charged than their folded counterparts. A chain ejection model (CEM) has been proposed to account for the protein ESI behavior under such non-native conditions …
Imaging The Surface Of A Hand-Colored 19th Century Daguerreotype., Madalena S Kozachuk, Maria O Avilés, Ronald R Martin, Brianne Potts, Tsun-Kong Sham, François Lagugné-Labarthet
Imaging The Surface Of A Hand-Colored 19th Century Daguerreotype., Madalena S Kozachuk, Maria O Avilés, Ronald R Martin, Brianne Potts, Tsun-Kong Sham, François Lagugné-Labarthet
Chemistry Publications
Daguerreotypes are valued artifacts that constitute a unique historical photographic memory of the 19th century. Understanding their surface chemistry is important in order to conserve and, when necessary, to restore them. Colored highlights were often added by hand to emphasize different features on the daguerreotype's subjects. In the present work, we report on a daguerreotype that was hand-colored with a red pigment that was added to the cheeks of the two individuals. A series of experiments using micro-Raman and micro-Fourier transform infrared spectroscopy and synchrotron-based X-ray fluorescence microscopy and absorption spectroscopy are used to analyze the surface and to determine …
Controlled Polymerization Of Ethyl Glyoxylate Using Alkyllithium And Alkoxide Initiators, Amir Rabiee Kenaree, Elizabeth R. Gillies
Controlled Polymerization Of Ethyl Glyoxylate Using Alkyllithium And Alkoxide Initiators, Amir Rabiee Kenaree, Elizabeth R. Gillies
Chemistry Publications
The synthesis of poly(ethyl glyoxylate)s (PEtGs) by anionic polymerization was explored. PEtGs are a subclass of stimuli-responsive self-immolative polymers with promising properties for applications as coatings, sensors, and drug delivery vehicles. In this report, a new purification procedure for the preparation of highly pure ethyl glyoxylate (EtG), suitable for anionic polymerization reactions, and the first successful examples of controlled polymerization of EtG are described. n-BuLi, PhLi, and t-BuLi were employed as initiators under different experimental conditions and their behavior was examined using NMR spectroscopy, size exclusion chromatography, and thermal analysis to develop an optimized procedure. As functional alkoxide …
How To Run Molecular Dynamics Simulations On Electrospray Droplets And Gas Phase Proteins: Basic Guidelines And Selected Applications., Lars Konermann, Haidy Metwally, Robert G Mcallister, Vlad Popa
How To Run Molecular Dynamics Simulations On Electrospray Droplets And Gas Phase Proteins: Basic Guidelines And Selected Applications., Lars Konermann, Haidy Metwally, Robert G Mcallister, Vlad Popa
Chemistry Publications
The ability to transfer intact proteins and protein complexes into the gas phase by electrospray ionization (ESI) has opened up numerous mass spectrometry (MS)-based avenues for exploring biomolecular structure and function. However, many details regarding the ESI process and the properties of gaseous analyte ions are difficult to decipher when relying solely on experimental data. Molecular dynamics (MD) simulations can provide additional insights into the behavior of ESI droplets and protein ions. This review is geared primarily towards experimentalists who wish to adopt MD simulations as a complementary research tool. We touch on basic points such as force fields, the …
Formazanate Complexes Of Hypervalent Group‐14 Elements As Precursors To Electronically Stabilized Radicals, Ryan R. Maar, Sara D. Catingan, Viktor N. Staroverov, Joe Gilroy
Formazanate Complexes Of Hypervalent Group‐14 Elements As Precursors To Electronically Stabilized Radicals, Ryan R. Maar, Sara D. Catingan, Viktor N. Staroverov, Joe Gilroy
Chemistry Publications
The stability of molecular radicals containing main‐group elements usually hinges on the presence of bulky substituents that shield the reactive radical center. We describe a family of group‐14 formazanate complexes whose chemical reduction allows access to radicals that are stabilized instead by geometric and electron‐delocalization effects, specifically by the square‐pyramidal geometry adopted by the group‐14 atom (Si, Ge, Sn) within the framework of the heteroatom‐rich formazanate ligands. The reduction potentials of the Si, Ge, and Sn complexes as determined by cyclic voltammetry become more negative in that order. Examination of the solid‐state structures of these complexes suggested that their electron‐accepting …
Effects Of Dispersion Corrections And Nonlocality On Density Functional Predictions Of Pressure-Induced Polymorphic Transitions Of Crystalline Diborane, Angela M. Murcia Rios, Darya N. Komsa, Viktor N. Staroverov
Effects Of Dispersion Corrections And Nonlocality On Density Functional Predictions Of Pressure-Induced Polymorphic Transitions Of Crystalline Diborane, Angela M. Murcia Rios, Darya N. Komsa, Viktor N. Staroverov
Chemistry Publications
The role of dispersion interactions in density functional calculations of the relative enthalpies of compressed BH3 polymorphs was investigated using plane-wave and Gaussian basis set codes. Addition of semiempirical atom-pairwise dispersion corrections to generalized gradient approximations (GGAs) was found to have little effect on the relative enthalpies of various boron hydride structures. By contrast, the stability ranking obtained with the nonlocal van der Waals density functional (vdW-DF) of Dion and co-workers was substantially more realistic than the rankings predicted by plain and dispersion-corrected GGAs. Of the functionals tested, only vdW-DF correctly predicts that compressed diborane does not leave the B2H6 …
A Π-Conjugated Inorganic Polymer Constructed From Boron Difluoride Formazanates And Platinum(Ii) Diynes, Jasveer S. Dhindsa, Ryan R. Maar, Stephanie M. Barbon, Maria Olivia Avilés, Zachary K. Powell, Francois Lagugné-Labarthet, Joe Gilroy
A Π-Conjugated Inorganic Polymer Constructed From Boron Difluoride Formazanates And Platinum(Ii) Diynes, Jasveer S. Dhindsa, Ryan R. Maar, Stephanie M. Barbon, Maria Olivia Avilés, Zachary K. Powell, Francois Lagugné-Labarthet, Joe Gilroy
Chemistry Publications
The first example of a π-conjugated polymer incorporating boron difluoride (BF2) formazanates is introduced. The film-forming properties, controllable reduction chemistry, and low optical band gap (ca. 1.4 eV) of the polymer make it an excellent candidate for use as a light-harvesting n-type semiconductor in organic electronics. Comparison of the polymer to model compounds confirmed that its unique optoelectronic properties can be directly attributed to the presence of the BF2 formazanate repeat unit and that the [Pt(PBu3)2]2+ unit must also be present to achieve the narrow band gaps observed.
Depolymerization Of Trityl End-Capped Poly(Ethyl Glyoxylate): Potential Applications In Smart Packaging, Bo Fan, Romulo Salazar, Elizabeth R. Gillies
Depolymerization Of Trityl End-Capped Poly(Ethyl Glyoxylate): Potential Applications In Smart Packaging, Bo Fan, Romulo Salazar, Elizabeth R. Gillies
Chemistry Publications
The temperature-dependent depolymerization of self-immolative poly(ethyl glyoxylate) (PEtG) capped with triphenylmethyl (trityl) groups was studied and its potential application for smart packaging was explored. PEtGs with four different trityl end-caps were prepared and found to undergo depolymerization to volatile products from the solid state at different rates depending on temperature and the electron-donating substituents on the trityl aromatic rings. Through the incorporation of hydrophobic dyes including Nile red and IR-780, the depolymerization was visualized as a color change of the dye as it changed from a dispersed to aggregated state. The ability of this platform to provide information on thermal …
Plasmon-Mediated Drilling In Thin Metallic Nanostructures, Francois Lagugne-Labarthet, D. M. Mrae, K. Jeon
Plasmon-Mediated Drilling In Thin Metallic Nanostructures, Francois Lagugne-Labarthet, D. M. Mrae, K. Jeon
Chemistry Publications
Thin and ultraflat conductive surfaces are of particular interest to use as substrates for tip-enhanced spectroscopy applications. Tip-enhanced spectroscopy exploits the excitation of a localized surface plasmon resonance mode at the apex of a metallized atomic force microscope tip, confining and enhancing the local electromagnetic field by several orders of magnitude. This allows for nanoscale mapping of the surface with high spatial resolution and surface sensitivity, as demonstrated when coupled to local Raman measurements. In gap-mode tip-enhanced spectroscopy, the specimen of interest is deposited onto a flat metallic surface and probed by a metallic tip, allowing for further electromagnetic confinement …
Tuning The Hydrophobic Cores Of Self-Immolative Polyglyoxylate Assemblies, Bo Fan, Rebecca E. Yardley, John F. Trant, Aneta Borecki, Elizabeth R. Gillies
Tuning The Hydrophobic Cores Of Self-Immolative Polyglyoxylate Assemblies, Bo Fan, Rebecca E. Yardley, John F. Trant, Aneta Borecki, Elizabeth R. Gillies
Chemistry Publications
Polyglyoxylates are a recently-introduced class of self-immolative polymers, that depolymerize to small molecules upon the cleavage of a stimuli-responsive end-cap from the polymer terminus. The incorporation of different pendant ester groups or other aldehyde monomers offers the potential to tune the polymer properties, but this remains largely unexplored. With the goal of tuning the self-assembly and drug-loading properties of polyglyoxylate block copolymers, we explored the polymerization and copolymerization of n-butyl glyoxylate, L-menthyl glyoxylate, and chloral with ethyl glyoxylate to form UV light-responsive polyglyoxylates. The resulting polymers were coupled to poly(ethylene glycol) to afford amphiphilic block copolymers. Self-assembly of the …
Group 13 Complexes Of Chelating N2o2n‒ Ligands As Hybrid Molecular Materials, Ryan R. Maar, Joe B. Gilroy
Group 13 Complexes Of Chelating N2o2n‒ Ligands As Hybrid Molecular Materials, Ryan R. Maar, Joe B. Gilroy
Chemistry Publications
Recent synthetic advances have afforded opportunities for the creation of a wide range of potentially tetradentate N2O2n‒ ligands. When combined with group 13 elements, robust functional molecular materials can be realized. This concept article describes advances surrounding group 13 complexes of selected families of N2O2n‒ ligands, including examples with unique chirality, sensing/detection capabilities, utility in organic electronics, and redox properties. It also highlights the bridge between fundamental main group chemistry and useful application that is being established within this research field.
Detection Of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (Maldi Ms)., Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung
Detection Of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (Maldi Ms)., Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung
Chemistry Publications
The use of MALDI MS as a fast and direct method to detect the Aβ oligomers of different masses is examined in this paper. Experimental results suggest that Aβ oligomers are ionized and detected as singly charged ions, and thus, the resulting mass spectrum directly reports the oligomer size distribution. Validation experiments were performed to verify the MS data against artifacts. Mass spectra collected from modified Aβ peptides with different propensities for aggregation were compared. Generally, the relative intensities of multimers were higher from samples where oligomerization was expected to be more favorable, and vice versa. MALDI MS was also …
Crown Ether Effects On The Location Of Charge Carriers In Electrospray Droplets: Implications For The Mechanism Of Protein Charging And Supercharging., Haidy Metwally, Lars Konermann
Crown Ether Effects On The Location Of Charge Carriers In Electrospray Droplets: Implications For The Mechanism Of Protein Charging And Supercharging., Haidy Metwally, Lars Konermann
Chemistry Publications
"Native" electrospray ionization (ESI) mass spectrometry (MS) aims to transfer proteins from solution into the gas phase while maintaining solution-like structures and interactions. The ability to control the charge states of protein ions produced in these experiments is of considerable importance. Supercharging agents (SCAs) such as sulfolane greatly elevate charge states without significantly affecting the protein structure in bulk aqueous solution. The origin of native ESI supercharging remains contentious. According to one model, SCAs trigger unfolding within ESI droplets. In contrast, the "charge trapping model" envisions that SCAs impede the ejection of charge carriers (e.g., NH4+ or Na …
Exploiting Anisotropy Of Plasmonic Nanostructures With Polarization-Modulation Infrared Linear Dichroism Microscopy (Μpm-Irld)., Gregory Q. Wallace, Stuart Read, Danielle M. Mcrae, Scott Rosendhal, Francois Lagugne-Labarthet
Exploiting Anisotropy Of Plasmonic Nanostructures With Polarization-Modulation Infrared Linear Dichroism Microscopy (Μpm-Irld)., Gregory Q. Wallace, Stuart Read, Danielle M. Mcrae, Scott Rosendhal, Francois Lagugne-Labarthet
Chemistry Publications
Metallic nanostructures that exhibit plasmon resonances in the mid-infrared range are of particular interest for a variety of optical processes where the infrared excitation and/or emission could be enhanced. This plasmon-mediated enhancement can potentially be used towards highly sensitive detection of an analyte(s) by techniques such as surface-enhanced infrared absorption (SEIRA). To maximize the SEIRA enhancement, it is necessary to prepare highly tuned plasmonic resonances over a defined spectral range that can span over several microns. Noteworthy, nanostructures with anisotropic shapes exhibit multiple resonances that can be exploited by controlling the polarization of the input light. This study demonstrates the …
Structural Tuning Of Boron Difluoride Formazanate Electrochemiluminescence Mediated By Tri-N-Propylamine, Mahdi Hesari, Stephanie M. Barbon, Rayner B. Mendes, Viktor N. Staroverov, Zhifeng Ding, Joe Gilroy
Structural Tuning Of Boron Difluoride Formazanate Electrochemiluminescence Mediated By Tri-N-Propylamine, Mahdi Hesari, Stephanie M. Barbon, Rayner B. Mendes, Viktor N. Staroverov, Zhifeng Ding, Joe Gilroy
Chemistry Publications
Electrochemistry and electrogenerated chemiluminescence (ECL) of boron difluoride formazanate complexes bearing p-methoxyphenyl N-substituents were studied experimentally and computationally. It was shown that the substituents at the 3-position (R3) of the formazanate backbone play a critical role in the electrochemistry and ECL of the complexes in the presence of tri-n-propylamine (TPrA). The ECL emission of 1a (R3 = cyano), 1b (R3 = phenyl), and 1c (R3 = p-C6H4OMe) occurred at peak wavelengths of 724 nm (1.71 eV), 704 nm (1.76 eV), and 723 nm (1.71 eV), consistent …
Radical Chemistry In A Femtosecond Laser Plasma: Photochemical Reduction Of Ag+ In Liquid Ammonia Solution, Victoria K. Meader, Mallory G. John, Laysa M. Frias Batista, Syeda Ahsan, Katharine M. Tibbetts
Radical Chemistry In A Femtosecond Laser Plasma: Photochemical Reduction Of Ag+ In Liquid Ammonia Solution, Victoria K. Meader, Mallory G. John, Laysa M. Frias Batista, Syeda Ahsan, Katharine M. Tibbetts
Chemistry Publications
Plasmas with dense concentrations of reactive species such as hydrated electrons and hydroxyl radicals are generated from focusing intense femtosecond laser pulses into aqueous media. These radical species can reduce metal ions such as Au3+ to form metal nanoparticles (NPs). However, the formation of H2O2 by the recombination of hydroxyl radicals inhibits the reduction of Ag+ through back-oxidation. This work has explored the control of hydroxyl radical chemistry in a femtosecond laser-generated plasma through the addition of liquid ammonia. The irradiation of liquid ammonia solutions resulted in a reaction between NH3 and OH·, forming peroxynitrite and ONOO−, and significantly reducing …
Electrokinetic Flow Of Aqueous Electrolyte In Amorphous Silica Nanotubes, Chris D. Daub, Natalie Cann, D. Bratko, Alenka Luzar
Electrokinetic Flow Of Aqueous Electrolyte In Amorphous Silica Nanotubes, Chris D. Daub, Natalie Cann, D. Bratko, Alenka Luzar
Chemistry Publications
We study the pressure-driven flow of aqueous NaCl in amorphous silica nanotubes using nonequilibrium molecular dynamics simulations featuring both polarizable and non-polarizable molecular models. Different pressures, electrolyte concentrations and pore sizes are examined. Our results indicate a flow that deviates considerably from the predictions of Poiseuille fluid mechanics. Due to preferential adsorption of the different ionic species by surface SiO! or SiOH groups, we find that a significant electric current is generated, but with opposite polarities using polarizable vs. fixed charge models for water and ions, emphasizing the need for careful parameterization in such complex systems. We also examine the …
Curvature Dependence Of The Effect Of Ionic Functionalization On The Attraction Among Nanoparticles In Dispersion, B. Shadrack Jabes, D. Bratko, Alenka Luzar
Curvature Dependence Of The Effect Of Ionic Functionalization On The Attraction Among Nanoparticles In Dispersion, B. Shadrack Jabes, D. Bratko, Alenka Luzar
Chemistry Publications
Solubilization of nanoparticles facilitates nanomaterial processing and enables new applications. An effective method to improve dispersibility in water is provided by ionic functionalization.We explore how the necessary extent of functionalization depends on the particle geometry. Using molecular dynamics/umbrella sampling simulations, we determine the effect of the solute curvature on solventaveraged interactions among ionizing graphitic nanoparticles in aqueous dispersion. We tune the hydrophilicity of molecular-brush coated fullerenes, carbon nanotubes, and graphane platelets by gradually replacing a fraction of the methyl end groups of the alkyl coating by the ionizing –COOK or –NH3Cl groups. To assess the change in nanoparticles’ dispersibility in …
Nucleation And Growth Of Gold Nanoparticles Initiated By Nanosecond And Femtosecond Laser Irradiation Of Aqueous [Aucl4]-, Collin Rodrigues, Julian A. Bobb, Mallory G. John, Sergey Fisenko, M. S. El-Shall, Katharine M. Tibbetts
Nucleation And Growth Of Gold Nanoparticles Initiated By Nanosecond And Femtosecond Laser Irradiation Of Aqueous [Aucl4]-, Collin Rodrigues, Julian A. Bobb, Mallory G. John, Sergey Fisenko, M. S. El-Shall, Katharine M. Tibbetts
Chemistry Publications
Irradiation of aqueous [AuCl4]with 532 nm nanosecond (ns) laser pulses produces monodisperse (PDI = 0.04) 5 nm Au nanoparticles (AuNPs) without any additives or capping agents via a plasmon- enhanced photothermal autocatalytic mechanism. Compared with 800 nm femtosecond (fs) laser pulses, the AuNP growth kinetics under ns laser irradiation follow the same autocatalytic rate law, but with a significantly lower sensitivity to laser pulse energy. The results are explained using a simple model for simulating heat transfer in liquid water and at the interface with AuNPs. While the extent of water superheating with the ns laser is smaller compared to …
Polymer Assembly Encapsulation Of Lanthanide Nanoparticles As Contrast Agents For In Vivo Micro-Ct, Charmainne Cruje, Joy Dunmore-Buyze, Jarret P. Macdonald, David W. Holdsworth, Maria Drangova, Elizabeth R. Gillies
Polymer Assembly Encapsulation Of Lanthanide Nanoparticles As Contrast Agents For In Vivo Micro-Ct, Charmainne Cruje, Joy Dunmore-Buyze, Jarret P. Macdonald, David W. Holdsworth, Maria Drangova, Elizabeth R. Gillies
Chemistry Publications
Despite recent technological advancements in microcomputed tomography (micro-CT) and contrast agent development, pre-clinical contrast agents are still predominantly iodine-based. Higher contrast can be achieved when using elements with higher atomic numbers, such as lanthanides; lanthanides also have x-ray attenuation properties that are ideal for spectral CT. However, the formulation of lanthanide-based contrast agents at the high concentrations required for vascular imaging presents a significant challenge. In this work, we developed an erbium-based contrast agent that meets micro-CT imaging requirements, which include colloidal stability upon redispersion at high concentrations, evasion of rapid renal clearance, and circulation times of tens of minutes …
Microencapsulation By In Situ Polymerization Of Amino Resins, Olivier Nguon, Francois Lagugne-Labarthet, 3m Company Canada, Elizabeth R. Gillies
Microencapsulation By In Situ Polymerization Of Amino Resins, Olivier Nguon, Francois Lagugne-Labarthet, 3m Company Canada, Elizabeth R. Gillies
Chemistry Publications
By surrounding small droplets with a coating, one can obtain micrometer-size capsules (microcapsules), and combine multiple properties into a single system. This technology has allowed the design of advanced and functional materials. Amino resins are composed principally of urea and/or melamine and formaldehyde, and exhibit advantages as wall-forming materials, such as high mechanical strength and chemical resistance. In this review, a general description of the encapsulation process by in situ polymerization of amino resins is given. Characterization methods, and the influence of the physical and design parameters are discussed. A mechanistic description, and some of the promising avenues of research …
Dialkynylborane Complexes Of Formazanate Ligands: Synthesis, Electronic Properties, And Reactivity, Alex Van Belois, Ryan R. Maar, Mark S. Workentin, Joe Gilroy
Dialkynylborane Complexes Of Formazanate Ligands: Synthesis, Electronic Properties, And Reactivity, Alex Van Belois, Ryan R. Maar, Mark S. Workentin, Joe Gilroy
Chemistry Publications
Dialkynylborane complexes of N-donor ligands have received significant attention due to their application in biological imaging, as light-harvesting materials, and as the functional component of organic photovoltaics. Despite these advances, relatively few types of N-donor ligands have been explored in this context. To this end, we prepared a series of dialkynylborane complexes of formazanate ligands and explored their electronic properties and reactivity. In doing so, we demonstrated that: 1) The nature of the alkynyl substituents has little influence over the UV-vis absorption properties of the title complexes, but does affect the potentials at which they are electrochemically oxidized …
Uniform Electron Gas Limit Of An Exact Expression For The Kohn–Sham Exchange-Correlation Potential, Viktor N. Staroverov
Uniform Electron Gas Limit Of An Exact Expression For The Kohn–Sham Exchange-Correlation Potential, Viktor N. Staroverov
Chemistry Publications
Previously, we derived an exact formula for the Kohn–Sham exchange-correlation potential corresponding, in the basis-set limit, to the Hartree–Fock electron density of a given system. This formula expresses the potential in terms of the occupied Hartree–Fock and Kohn–Sham orbitals and orbital energies. Here, we show that, when applied to the Hartree–Fock description of a uniform electron gas, the formula correctly reduces to the exchange-only local density approximation.