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Articles 1 - 30 of 326
Full-Text Articles in Physical Sciences and Mathematics
Two-Electron Density Of Three Electrons In A 1d Box: A Model System For Visualizing Spin Correlation Due To Antisymmetry Of Electrons, Joseph D. Alia
Two-Electron Density Of Three Electrons In A 1d Box: A Model System For Visualizing Spin Correlation Due To Antisymmetry Of Electrons, Joseph D. Alia
Chemistry Publications
Visual models for understanding electron density distribution in molecules are useful for chemical reasoning. The Lewis structure for example compares well to one-electron density when all electrons are paired. Linnett Double Quartet structures compare well to some kinds of free radical species. These approaches do not show the behavior of the total electron wavefunction when two electrons near each other. This behavior is a two- electron property and can be visualized with the model of three electrons in a one- dimensional box. The two-electron density of the three electron wavefunction described as a slater determinent of 1D particle-in-a-box spin- orbitals …
3d Pictorial Representations Of O2- And Ho2 Compared To Dft Results, Tzu-Hsiang Huang, Joseph D. Alia
3d Pictorial Representations Of O2- And Ho2 Compared To Dft Results, Tzu-Hsiang Huang, Joseph D. Alia
Chemistry Publications
The Linnett Double Quartet (LDQ) (1) and Bohr Orbit Bonding (BOB) (2) methods were used to accurately represent the spin density distribution for superoxide (O2 -) and hydroperoxyl radical (HO2). These structural pictures were superimposed on the spin density plot produced by DFT. The Valency Interaction Formula (VIF) method (3) was also applied to these molecules and it matched the NBOs from NBO analysis of DFT results. The interaction between O2 - and H2O were analyzed and the stronger basicity of the beta-spin electrons of superoxide was identified by looking at the LDQ structure and confirmed with NBO analysis. The …
Effect Of Passivation And Surface Treatment Of A Laser Powder Bed Fusion Biomedical Titanium Alloy On Corrosion Resistance And Protein Adsorption, Saman Nikpour, Jeffrey Henderson, Sina Matin, Heng-Yong Nie, Jonas Hedberg, Vahid Dehnavi, Yara Hosein, David Holdsworth, Mark Biesinger, Yolanda Hedberg
Effect Of Passivation And Surface Treatment Of A Laser Powder Bed Fusion Biomedical Titanium Alloy On Corrosion Resistance And Protein Adsorption, Saman Nikpour, Jeffrey Henderson, Sina Matin, Heng-Yong Nie, Jonas Hedberg, Vahid Dehnavi, Yara Hosein, David Holdsworth, Mark Biesinger, Yolanda Hedberg
Chemistry Publications
The biomedical titanium alloy Ti6Al4V has excellent corrosion resistance and biocompatibility and is, therefore, widely used in orthopedic and orthodontic implants. Biomedical implants are increasingly fabricated by additive manufacturing, such as laser powder bed fusion (LPBF). These manufacturing protocols often include sandblasting, surface finish, and passivation. This study aims to investigate the effect of different surface finishes and the commonly used ASTM F86-13 nitric acid passivation for LPBF Ti6Al4V on its corrosion resistance, metal release, and surface changes in benign (bovine serum albumin in a pH 7.4 buffer) and harsh (hydrochloric acid at pH 1.5) solutions using various electrochemical and …
A Bio-Tribocorrosion Comparison Between Additively Manufactured And Forged Ti6al4v Parts, Sina Matin, Sahar Toorandaz, Saman Nikpour, Hamidreza Abdolvand, Eshan Toyserkani, Yolanda S. Hedberg
A Bio-Tribocorrosion Comparison Between Additively Manufactured And Forged Ti6al4v Parts, Sina Matin, Sahar Toorandaz, Saman Nikpour, Hamidreza Abdolvand, Eshan Toyserkani, Yolanda S. Hedberg
Chemistry Publications
Ti6Al4V has been used widely as a biomedical alloy and is increasingly manufactured by additive manufacturing due to customized shapes. As implant material, it is frequently exposed to both friction and corrosive environments. This study investigates the effect of the fabrication process (laser powder bed fusion and forging) on the tribocorrosion behavior of Ti6Al4V in various environments including diluted hydrochloric acid to simulate the acidic environment in a crevice (HCl), phosphate-buffered saline (pH 7.3) with 10 g/L bovine serum albumin (PBS+BSA), and PBS+BSA with 30 mM H2O2. While the presence of BSA hindered the repassivation (reforming of the protective passive …
Synergistic Effect Of Nanoclay And Barium Sulfate Fillers On The Corrosion Resistance Of Polyester Powder Coatings, Jinbao Huang, Marshall Shuai Yang, Chengqian Xian, James Joseph Noel, Yolanda S. Hedberg, Jian Chen, Ubong Eduok, Ivan Barker, Jeffrey Daniel Henderson, Haiping Zhang, Liqin Wang, Hui Zhang, Jesse Zhu
Synergistic Effect Of Nanoclay And Barium Sulfate Fillers On The Corrosion Resistance Of Polyester Powder Coatings, Jinbao Huang, Marshall Shuai Yang, Chengqian Xian, James Joseph Noel, Yolanda S. Hedberg, Jian Chen, Ubong Eduok, Ivan Barker, Jeffrey Daniel Henderson, Haiping Zhang, Liqin Wang, Hui Zhang, Jesse Zhu
Chemistry Publications
No abstract provided.
Study On The Self-Repairing Effect Of Nanoclay In Powder Coatings For Corrosion Protection, Marshall S. Yang, Jinbao Huang, Hui Zhhang, James Noel, Yolanda S. Hedberg, Jian Chen, Ubong Eduok, Ivan Barker, Jeffrey D. Henderson, Chengqian Xian, Haiping Zhang, Jesse Zhu
Study On The Self-Repairing Effect Of Nanoclay In Powder Coatings For Corrosion Protection, Marshall S. Yang, Jinbao Huang, Hui Zhhang, James Noel, Yolanda S. Hedberg, Jian Chen, Ubong Eduok, Ivan Barker, Jeffrey D. Henderson, Chengqian Xian, Haiping Zhang, Jesse Zhu
Chemistry Publications
Powder coatings are a promising, solvent-free alternative to traditional liquid coatings due to the superior corrosion protection they provide. This study investigates the effects of incorporating montmorillonite-based nanoclay additives with different particle sizes into polyester/triglycidyl isocyanurate (polyester/TGIC) powder coatings. The objective is to enhance the corrosion-protective function of the coatings while addressing the limitations of commonly employed epoxy-based coating systems that exhibit inferior UV resistance. The anti-corrosive and surface qualities of the coatings were evaluated via neutral salt spray tests, electrochemical measurements, and surface analytical techniques. Results show that the nanoclay with a larger particle size of 18.38 µm (D50, …
Skin Permeation Studies Of Chromium Species - Evaluation Of A Reconstructed Human Epidermis Model., L Hagvall, M Munem, M Hoang Philipsen, M Dowlatshahi Pour, Yolanda S. Hedberg, P Malmberg
Skin Permeation Studies Of Chromium Species - Evaluation Of A Reconstructed Human Epidermis Model., L Hagvall, M Munem, M Hoang Philipsen, M Dowlatshahi Pour, Yolanda S. Hedberg, P Malmberg
Chemistry Publications
A reconstructed human epidermis (RHE) model, the EpiDerm, was investigated and compared to human skin ex vivo regarding tissue penetration and distribution of two chromium species, relevant in both occupational and general exposure in the population. Imaging mass spectrometry was used in analysis of the sectioned tissue. The RHE model gave similar results compared to human skin ex vivo for skin penetration of Cr
Corrosion Case Study On Automobile, Grace Ajayi, Xinran Pan, Geethu Sasikala, Marshall S. Yang
Corrosion Case Study On Automobile, Grace Ajayi, Xinran Pan, Geethu Sasikala, Marshall S. Yang
Chemistry Publications
No abstract provided.
Designing Polymers With Stimuli-Responsive Degradation For Biomedical Applications, Chuanfeng Li, Zhengyu Deng, Elizabeth R. Gillies
Designing Polymers With Stimuli-Responsive Degradation For Biomedical Applications, Chuanfeng Li, Zhengyu Deng, Elizabeth R. Gillies
Chemistry Publications
Early biomedical applications of polymers were in areas such as joint replacements and often involved durable polymers. However, biodegradable polymers are increasingly being used to perform temporary functions such as drug delivery or supporting cells, after which they can break down and be eliminated from the body. Polymers that degrade specifically in response to stimuli offer additional opportunities to control when and where this degradation occurs, enabling enhanced functions such as site-specific drug release and the early detection of disease. In this article, we will discuss recent advancements in the design, preparation, and application of stimuli-responsive polymer degradation. In …
Atomistic Details Of Peptide Reversed-Phase Liquid Chromatography From Molecular Dynamics Simulations, Pablo M Scrosati, Lars Konermann
Atomistic Details Of Peptide Reversed-Phase Liquid Chromatography From Molecular Dynamics Simulations, Pablo M Scrosati, Lars Konermann
Chemistry Publications
Peptide separations by reversed-phase liquid chromatography (RPLC) are an integral part of bottom-up proteomics. These separations typically employ C18 columns with water/acetonitrile gradient elution in the presence of formic acid. Despite the widespread use of such workflows, the exact nature of peptide interactions with the stationary and mobile phases are poorly understood. Here we employ microsecond molecular dynamics (MD) simulations to uncover details of peptide RPLC. We examined two tryptic peptides, a hydrophobic and a hydrophilic species, in a slit pore lined with C18 chains that were grafted onto SiO2 support. Our simulations explored peptide trapping, followed by desorption …
In Vitro Corrosion And Biocompatibility Behavior Of Cocrmo Alloy Manufactured By Laser Powder Bed Fusion Parallel And Perpendicular To The Build Direction, Masoud Atapour, Saber Sanaei, Zheng Wei, Mohammadali Sheikholeslam, Jeffrey D. Henderson, Ubong Eduok, Yara K. Hosein, David W. Holdsworth, Yolanda S. Hedberg, Hamid Reza Ghorbani
In Vitro Corrosion And Biocompatibility Behavior Of Cocrmo Alloy Manufactured By Laser Powder Bed Fusion Parallel And Perpendicular To The Build Direction, Masoud Atapour, Saber Sanaei, Zheng Wei, Mohammadali Sheikholeslam, Jeffrey D. Henderson, Ubong Eduok, Yara K. Hosein, David W. Holdsworth, Yolanda S. Hedberg, Hamid Reza Ghorbani
Chemistry Publications
Biomedical cobalt-chromium-molybdenum alloys (CoCrMo) are frequently used for orthopedic implant and dental materials exposed to mechanical stressors, such as wear and cyclic load. Due to the high demand for customizable implant shapes, these alloys are increasingly manufactured by additive manufacturing methods such as laser powder bed fusion (LPBF). LPBF results in different microstructures and surface roughness as a function of the building direction. This study investigated the corrosion resistance, bioactivity, biocompatibility, and microstructure of LPBF CoCrMo (low carbon content, heat-treated) in the XY (perpendicular) and XZ (parallel) plane of the building direction for as-printed (as-received) and abraded surfaces. A distinct …
Mechanism Of Magic Number Nacl Cluster Formation From Electrosprayed Water Nanodroplets., Lars Konermann, Yousef Haidar
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 …
Structural Dynamics Of A Thermally Stressed Monoclonal Antibody Characterized By Temperature-Dependent H/D Exchange Mass Spectrometry., Nastaran N Tajoddin, Lars Konermann
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.
Reconstruction Of Exchange–Correlation Potentials From Their Matrix Representations, Yan Oueis, Viktor N. Staroverov
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 …
The Ability Of Sweat And Buffer Solutions To Reduce Hexavalent Chromium Of Relevance For Leather Extraction, Alexandra Wright, Lila Laundry-Mottiar, Yolanda Hedberg
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, …
Noninteracting V-Representable Subspaces Of Orbitals In The Kohn–Sham Method, Viktor N. Staroverov
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 …
Grotthuss Molecular Dynamics Simulations For Modeling Proton Hopping In Electrosprayed Water Droplets., Lars Konermann, Scott Kim
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. …
Formation Of Gaseous Peptide Ions From Electrospray Droplets: Competition Between The Ion Evaporation Mechanism And Charged Residue Mechanism., Elnaz Aliyari, Lars Konermann
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 …
Self-Immolative Polyplexes For Dna Delivery, Quinton E. A. Sirianni, Tianduo Wang, Aneta Borecki, Zhengyu Deng, Elizabeth R. Gillies, John A. Ronald
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 …
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
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.
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
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, …
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
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 …
Generation Of Nanomaterials By Reactive Laser Synthesis In Liquid, Laysa M. Frias Batista, Ashish B. Nag, Victoria K. Meader, Katharine M. Tibbetts
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 …
Benzothiazole-Substituted Boron Difluoride Formazanate Dyes, Francis L. Buguis, Paul D. Boyle, Joe B. Gilroy
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 …
Mechanism Of Thermal Protein Aggregation: Experiments And Molecular Dynamics Simulations On The High-Temperature Behavior Of Myoglobin., Yuen Ki Ng, Nastaran N Tajoddin, Pablo M Scrosati, Lars Konermann
Mechanism Of Thermal Protein Aggregation: Experiments And Molecular Dynamics Simulations On The High-Temperature Behavior Of Myoglobin., Yuen Ki Ng, Nastaran N Tajoddin, Pablo M Scrosati, Lars Konermann
Chemistry Publications
Proteins that encounter unfavorable solvent conditions are prone to aggregation, a phenomenon that remains poorly understood. This work focuses on myoglobin (Mb) as a model protein. Upon heating, Mb produces amorphous aggregates. Thermal unfolding experiments at low concentration (where aggregation is negligible), along with centrifugation assays, imply that Mb aggregation proceeds via globally unfolded conformers. This contrasts studies on other proteins that emphasized the role of partially folded structures as aggregate precursors. Molecular dynamics (MD) simulations were performed to gain insights into the mechanism by which heat-unfolded Mb molecules associate with one another. A prerequisite for these simulations was the …
Metal Release From A Biomedical Cocrmo Alloy In Mixed Protein Solutions Under Static And Sliding Conditions: Effects Of Protein Aggregation And Metal Precipitation, Zheng Wei, Valentine Romanovski, Luimar Filho, Cecilia Persson, Yolanda S. Hedberg
Metal Release From A Biomedical Cocrmo Alloy In Mixed Protein Solutions Under Static And Sliding Conditions: Effects Of Protein Aggregation And Metal Precipitation, Zheng Wei, Valentine Romanovski, Luimar Filho, Cecilia Persson, Yolanda S. Hedberg
Chemistry Publications
Biomedical materials made of cobalt-chromium-molybdenum (CoCrMo) alloys are commonly used in artificial prostheses and dental implants, which are exposed to friction and load. The release of Co, Cr, and Mo from these surfaces is governed by physical and chemical processes. The extent of measured metal release from biomedical CoCrMo alloys into mixed protein solutions may be influenced by protein aggregation and metal precipitation effects. Metal release from, and the surface composition of, a CoCrMo alloy was investigated in physiological relevant solutions (phosphate buffered saline, PBS, with varying concentrations of fibrinogen from bovine plasma and/or bovine serum albumin) at pH 7.3 …
Characterization Of Ovarian Cancer-Derived Extracellular Vesicles By Surface-Enhanced Raman Spectroscopy., Nina M. Culum, Tyler T. Cooper, Gilles A. Lajoie, Thamara Dayarathna, Stephen H. Pasternak, Jiahui Liu, Yangxin Fu, Francois Lagugne-Labarthet, Lynne Marie Postovit
Characterization Of Ovarian Cancer-Derived Extracellular Vesicles By Surface-Enhanced Raman Spectroscopy., Nina M. Culum, Tyler T. Cooper, Gilles A. Lajoie, Thamara Dayarathna, Stephen H. Pasternak, Jiahui Liu, Yangxin Fu, Francois Lagugne-Labarthet, Lynne Marie Postovit
Chemistry Publications
Ovarian cancer is the most lethal gynecological malignancy, owing to the fact that most cases are diagnosed at a late stage. To improve prognosis and reduce mortality, we must develop methods for the early diagnosis of ovarian cancer. A step towards early and non-invasive cancer diagnosis is through the utilization of extracellular vesicles (EVs), which are nanoscale, membrane-bound vesicles that contain proteins and genetic material reflective of their parent cell. Thus, EVs secreted by cancer cells can be thought of as cancer biomarkers. In this paper, we present gold nanohole arrays for the capture of ovarian cancer (OvCa)-derived EVs and …
Polyglyoxylamides With A Ph-Mediated Solubility And Depolymerization Switch, Quinton E. A. Sirianni, Xiaoli Liang, Georgina K. Such, Elizabeth Gillies
Polyglyoxylamides With A Ph-Mediated Solubility And Depolymerization Switch, Quinton E. A. Sirianni, Xiaoli Liang, Georgina K. Such, Elizabeth Gillies
Chemistry Publications
Self-immolative polymers (SIPs) are characterized by their ability to depolymerize in response to the cleavage of a single end-cap or backbone moiety, making them attractive for numerous applications including sensors, transient plastics, and delivery vehicles. For many applications, it would be desirable to have an SIP capable of depolymerizing selectively under mildly acidic aqueous conditions. However, the poor solubility of most SIPs in water, accompanied by the competing effects of end-cap cleavage and depolymerization mechanisms, has made this a challenge. Here, we describe the development of polyglyoxylamides (PGAms) with pendent amino groups to achieve solubility switching at mildly acidic pH, …
Using Covalent Modifications To Distinguish Protein Electrospray Mechanisms: Charged Residue Model (Crm) Vs. Chain Ejection Model (Cem), Lars Konermann, Douglas J. D. Pimlott
Using Covalent Modifications To Distinguish Protein Electrospray Mechanisms: Charged Residue Model (Crm) Vs. Chain Ejection Model (Cem), Lars Konermann, Douglas J. D. Pimlott
Chemistry Publications
Different mechanisms have been proposed for the formation of gaseous protein ions during electrospray ionization (ESI). In the charged residue model (CRM) ions are produced upon nanodroplet evaporation to dryness. This mechanism is thought to dominate in native ESI, where proteins retain compact conformations, with charge states close to the Rayleigh charge of protein-sized aqueous droplets. Much higher charge states are generated from proteins that are unfolded in solution. The chain ejection model (CEM) has been proposed for ESI under such denaturing conditions. In the CEM proteins are gradually expelled, while mobile H+ equilibrate between the droplet and its …
Hydrogen/Deuterium Exchange Measurements May Provide An Incomplete View Of Protein Dynamics: A Case Study On Cytochrome, Pablo M Scrosati, Victor Yin, Lars Konermann
Hydrogen/Deuterium Exchange Measurements May Provide An Incomplete View Of Protein Dynamics: A Case Study On Cytochrome, Pablo M Scrosati, Victor Yin, Lars Konermann
Chemistry Publications
Many aspects of protein function rely on conformational fluctuations. Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) provides a window into these dynamics. Despite the widespread use of HDX-MS, it remains unclear whether this technique provides a truly comprehensive view of protein dynamics. HDX is mediated by H-bond-opening/closing events, implying that HDX methods provide an H-bond-centric view. This raises the question if there could be fluctuations that leave the H-bond network unaffected, thereby rendering them undetectable by HDX-MS. We explore this issue in experiments on cytochrome