Physical Sciences and Mathematics | Open Access Articles

Mechanism Of Magic Number Nacl Cluster Formation From Electrosprayed Water Nanodroplets., Lars Konermann, Yousef Haidar

Chemistry Publications

Events taking place during electrospray ionization (ESI) can trigger the self-assembly of various nanoclusters. These products are often dominated by magic number clusters (MNCs) that have highly symmetrical structures. The literature rationalizes the dominance of MNCs by noting their high stability. However, this argument is not necessarily adequate because thermodynamics cannot predict the outcome of kinetically controlled reactions. Thus, the mechanisms responsible for MNC dominance remain poorly understood. Molecular dynamics (MD) simulations can provide atomistic insights into self-assembly reactions, but even this approach has thus far failed to provide pertinent answers. The current work overcomes this limitation. We focused on …

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Structural Dynamics Of A Thermally Stressed Monoclonal Antibody Characterized By Temperature-Dependent H/D Exchange Mass Spectrometry., Nastaran N Tajoddin, Lars Konermann

Chemistry Publications

Differential scanning calorimetry (DSC) is a standard tool for probing the resilience of monoclonal antibodies (mAbs) and other protein therapeutics against thermal degradation. Unfortunately, DSC usually only provides insights into global unfolding, although sequential steps are sometimes discernible for multidomain proteins. Temperature-dependent hydrogen/deuterium exchange (HDX) mass spectrometry (MS) has the potential to probe heat-induced events at a much greater level of detail. We recently proposed a strategy to deconvolute temperature-dependent HDX data into contributions from local dynamics, global unfolding/refolding, as well as chemical labeling. However, that strategy was validated only for a small protein (Tajoddin, N. N.; Konermann, L.

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Reconstruction Of Exchange–Correlation Potentials From Their Matrix Representations, Yan Oueis, Viktor N. Staroverov

Chemistry Publications

Within a basis set of one-electron functions that form linearly independent products (LIPs), it is always possible to construct a unique local (multiplicative) real-space potential that is precisely equivalent to an arbitrary given operator. Although standard basis sets of quantum chemistry rarely form LIPs in a numerical sense, occupied and low-lying virtual canonical Kohn–Sham orbitals often do so, at least for small atoms and molecules. Using these principles, we construct atomic and molecular exchange–correlation potentials from their matrix representations in LIP basis sets of occupied canonical Kohn–Sham orbitals. The reconstructions are found to imitate the original potentials in a consistent …

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The Ability Of Sweat And Buffer Solutions To Reduce Hexavalent Chromium Of Relevance For Leather Extraction, Alexandra Wright, Lila Laundry-Mottiar, Yolanda Hedberg

Chemistry Publications

The European Union restricted the amount of hexavalent chromium (Cr(VI)) in leather in 2015, but skin allergy cases due to Cr-tanned leather are not declining. Standardized extraction methods have been criticized to both over- and underestimate the expected amount of bioavailable Cr(VI) in leather. This study aims to evaluate the ability of four extraction solutions to reduce or preserve Cr(VI): artificial sweat solutions (ASWs) of pH 4.7, 6.5, and 8.0, and phosphate buffer (PB) of pH 8.0. This was investigated by incubating each solution with added Cr(VI) as a function of time, and then measuring the recovered Cr(VI). All solutions, …

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Noninteracting V-Representable Subspaces Of Orbitals In The Kohn–Sham Method, Viktor N. Staroverov

Chemistry Publications

The notion of noninteracting v-representability is extended from electron densities to finite-dimensional linear subspaces of orbitals. Unlike electron densities, orbital subspaces can be tested for noninteracting v-representability using a transparent necessary condition: the subspace must be invariant under the action of some one-electron Kohn–Sham Hamiltonian. This condition allows one to determine in principle, and sometimes in practice, whether a given one-electron basis set can represent an N-electron density within the Kohn–Sham method and to find the corresponding Kohn–Sham effective potential v if it exists. If the occupied Kohn–Sham orbitals form linearly independent products, then their subspace is …

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Grotthuss Molecular Dynamics Simulations For Modeling Proton Hopping In Electrosprayed Water Droplets., Lars Konermann, Scott Kim

Chemistry Publications

Excess protons in water exhibit unique transport properties because they can rapidly hop along H-bonded water wires. Considerable progress has been made in unraveling this Grotthuss diffusion mechanism using quantum mechanical-based computational techniques. Unfortunately, high computational cost tends to restrict those techniques to small systems and short times. Molecular dynamics (MD) simulations can be applied to much larger systems and longer time windows. However, standard MD methods do not permit the dissociation/formation of covalent bonds, such that Grotthuss diffusion cannot be captured. Here, we bridge this gap by combining atomistic MD simulations (using Gromacs and TIP4P/2005 water) with proton hopping. …

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Formation Of Gaseous Peptide Ions From Electrospray Droplets: Competition Between The Ion Evaporation Mechanism And Charged Residue Mechanism., Elnaz Aliyari, Lars Konermann

Chemistry Publications

The transfer of peptide ions from solution into the gas phase by electrospray ionization (ESI) is an integral component of mass spectrometry (MS)-based proteomics. The mechanisms whereby gaseous peptide ions are released from charged ESI nanodroplets remain unclear. This is in contrast to intact protein ESI, which has been the focus of detailed investigations using molecular dynamics (MD) simulations and other methods. Under acidic liquid chromatography/MS conditions, many peptides carry a solution charge of 3+ or 2+. Because of this pre-existing charge and their relatively small size, prevailing views suggest that peptides follow the ion evaporation mechanism (IEM). The IEM …

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Self-Immolative Polyplexes For Dna Delivery, Quinton E. A. Sirianni, Tianduo Wang, Aneta Borecki, Zhengyu Deng, Elizabeth R. Gillies, John A. Ronald

Chemistry Publications

Nucleic acids have immense potential for the treatment and prevention of a wide range of diseases, but delivery vehicles are needed to assist with their entry into cells. Polycations can reversibly complex with nucleic acids via ionic interactions to form polyplexes and transport them into cells, but they are still hindered by the need to balance cytotoxicity and delivery effectiveness. In this work, we describe a new self-immolative polyglyoxylamide (PGAm) platform designed to address these challenges by complexing nucleic acids viamultivalent interactions in the polymeric form and releasing them upon depolymerization. Nine PGAms were synthesized and characterized, with different …

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Effect Of Nanoparticle Size On The Near-Surface Ph-Distribution In Aqueous And Carbonate Buffered Solutions, Thomas Stepan, Lisa Tété, Lila Laundry-Mottiar, Elena Romanovskaia, Yolanda S. Hedberg, Herbert Danninger, Michael Auinger

Chemistry Publications

An analytical solution for the effect of particle size on the current density and near-surface ion distribution around spherical nanoparticles is presented in this work. With the long-term aim to support predictions on corrosion reactions in the human body, the spherical diffusion equation was solved for a set of differential equations and algebraic relations for pure unbuffered and carbonate buffered solutions. It was shown that current densities increase significantly with a decrease in particle size, suggesting this will lead to an increased dissolution rate. Near-surface ion distributions show the formation of a steep pH-gradient near the nanoparticle surface (<6 μm) which is further enhanced in the presence of a carbonate buffer (<2 μm). Results suggest that nanoparticles in pure electrolytes not only dissolve faster than bigger particles but that local pH-gradients may influence interactions with the biological environment, which should be considered in future studies.

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Location Of Cobalt Impurities In The Surface Oxide Of Stainless Steel 316l And Metal Release In Synthetic Biological Fluids, Xuying Wang, Jonas Hedberg, Heng-Yong Nie, Mark Biesinger, Inger Odnevall, Yolanda S. Hedberg

Chemistry Publications

Since 2021, cobalt (Co) is in Europe classified as carcinogen in quantities exceeding 0.1 wt-%. This affects nickel-rich stainless steels, which contain about 0.2 wt-% Co impurities. Previous findings show the bioaccessibility of Co in stainless steel to be primarily determined by the corrosion resistance. It has been unclear whether Co is distributed heterogeneously in the alloy and the outermost surface and whether a specific location would pose a risk for Co release under specific exposure conditions. This study aimed at locating Co in stainless steel 316L (0.2 wt-% Co) surfaces prior to and after exposure to different synthetic body …

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Electrochemical Estimations Of The Gold Nanoparticle Size Effect On Cysteine-Gold Oxidation,, E. Romanovskaia, P. Slovenský, M. Kalantarian, L. Laundry-Mottiar, V. Romanovski, M. Halama, M. Auinger, Yolanda S. Hedberg

Chemistry Publications

Gold nanoparticles are interesting for nanobiomedical applications, such as for drug delivery and as diagnostic imaging contrast agents. However, their stability and reactivity in-vivo are influenced by their surface properties and size. Here, we investigate the electrochemical oxidation of differently sized citrate-coated gold nanoparticles in the presence and absence of L-cysteine, a thiol-containing amino acid with high binding affinity to gold. We found that smaller sized (5, 10 nm) gold nanoparticles were significantly more susceptible to electrochemical L-cysteine interactions and/or L-cysteine-facilitated gold oxidation than larger (20, 50 nm) sized gold nanoparticles, both for the same mass and nominal surface area, …

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Ultrafast Dynamics Of Nitro−Nitrite Rearrangement And Dissociation In Nitromethane Cation, Mi'kayla D. Word, Hugo Andres Lopez Pena, Derrick Ampadu Boateng, Shane L. Mcpherson, Gennady L. Gutsev, Lavrenty Gutsev, Ka Un Lao, Katharine M. Tibbetts

Chemistry Publications

We report new insights into the ultrafast rearrange- ment and dissociation dynamics of nitromethane cation (NM+) using pump−probe measurements, electronic structure calculations, and ab initio molecular dynamics simulations. The “roaming” nitro−nitrite rearrangement (NNR) pathway involving large- amplitude atomic motion, which has been previously described for neutral nitromethane, is demonstrated for NM+. Excess energy resulting from initial population of the electronically excited D2 state of NM+ upon strong-field ionization provides the necessary energy to initiate NNR and subsequent dissociation into NO+. Both pump−probe measurements and molecular dynamics simulations are consistent with the completion of NNR within 500 fs of ionization with …

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Generation Of Nanomaterials By Reactive Laser Synthesis In Liquid, Laysa M. Frias Batista, Ashish B. Nag, Victoria K. Meader, Katharine M. Tibbetts

Chemistry Publications

Nanomaterials with tailored structures and surface chemistry are in high demand, as these materials play increasingly important roles in biology, catalysis, energy storage, and manu- facturing. Their heightened demand has attracted attention towards the development of syn- thesis routes, particularly, laser-synthesis techniques. These efforts drove the refinement of laser ablation in liquid (LAL) and related methods over the past two decades, and have led to the emergence of reactive laser-synthesis techniques that exploit these methods’ character- istic, non-equilibrium conditions. Reactive laser-synthesis approaches foster unique chemical reactions that enable the formation of composite products like multimetallic nanoparticles, supported nanostructures, and complex …

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Benzothiazole-Substituted Boron Difluoride Formazanate Dyes, Francis L. Buguis, Paul D. Boyle, Joe B. Gilroy

Chemistry Publications

The incorporation of benzothiazole heterocycles into existing molecular frameworks has resulted in the production of a wide range of multifunctional molecular materials. However, this strategy has not yet been explored for an emerging class of boron difluoride dyes, derived from formazanate ligands, which often exhibit tuneable redox and optical properties. Here, we address this gap in the literature and describe the synthesis and characterization of a series of benzothiazole-substituted BF₂ formazanates. The incorporation of benzothiazole resulted in absorption profiles that were shifted to lower energies and reduction events that were shifted to more positive potentials when compared to those …

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Full-Text Articles in Physical Sciences and Mathematics

Mechanism Of Magic Number Nacl Cluster Formation From Electrosprayed Water Nanodroplets., Lars Konermann, Yousef Haidar

Chemistry Publications

Structural Dynamics Of A Thermally Stressed Monoclonal Antibody Characterized By Temperature-Dependent H/D Exchange Mass Spectrometry., Nastaran N Tajoddin, Lars Konermann

Chemistry Publications

Reconstruction Of Exchange–Correlation Potentials From Their Matrix Representations, Yan Oueis, Viktor N. Staroverov

Chemistry Publications

The Ability Of Sweat And Buffer Solutions To Reduce Hexavalent Chromium Of Relevance For Leather Extraction, Alexandra Wright, Lila Laundry-Mottiar, Yolanda Hedberg

Chemistry Publications

Noninteracting V-Representable Subspaces Of Orbitals In The Kohn–Sham Method, Viktor N. Staroverov

Chemistry Publications

Grotthuss Molecular Dynamics Simulations For Modeling Proton Hopping In Electrosprayed Water Droplets., Lars Konermann, Scott Kim

Chemistry Publications

Formation Of Gaseous Peptide Ions From Electrospray Droplets: Competition Between The Ion Evaporation Mechanism And Charged Residue Mechanism., Elnaz Aliyari, Lars Konermann

Chemistry Publications

Self-Immolative Polyplexes For Dna Delivery, Quinton E. A. Sirianni, Tianduo Wang, Aneta Borecki, Zhengyu Deng, Elizabeth R. Gillies, John A. Ronald

Chemistry Publications

Effect Of Nanoparticle Size On The Near-Surface Ph-Distribution In Aqueous And Carbonate Buffered Solutions, Thomas Stepan, Lisa Tété, Lila Laundry-Mottiar, Elena Romanovskaia, Yolanda S. Hedberg, Herbert Danninger, Michael Auinger

Chemistry Publications

Location Of Cobalt Impurities In The Surface Oxide Of Stainless Steel 316l And Metal Release In Synthetic Biological Fluids, Xuying Wang, Jonas Hedberg, Heng-Yong Nie, Mark Biesinger, Inger Odnevall, Yolanda S. Hedberg

Chemistry Publications

Electrochemical Estimations Of The Gold Nanoparticle Size Effect On Cysteine-Gold Oxidation,, E. Romanovskaia, P. Slovenský, M. Kalantarian, L. Laundry-Mottiar, V. Romanovski, M. Halama, M. Auinger, Yolanda S. Hedberg

Chemistry Publications

Ultrafast Dynamics Of Nitro−Nitrite Rearrangement And Dissociation In Nitromethane Cation, Mi'kayla D. Word, Hugo Andres Lopez Pena, Derrick Ampadu Boateng, Shane L. Mcpherson, Gennady L. Gutsev, Lavrenty Gutsev, Ka Un Lao, Katharine M. Tibbetts

Chemistry Publications

Generation Of Nanomaterials By Reactive Laser Synthesis In Liquid, Laysa M. Frias Batista, Ashish B. Nag, Victoria K. Meader, Katharine M. Tibbetts

Chemistry Publications

Benzothiazole-Substituted Boron Difluoride Formazanate Dyes, Francis L. Buguis, Paul D. Boyle, Joe B. Gilroy

Chemistry Publications