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- Electrospray Ionization (3)
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Articles 1 - 19 of 19
Full-Text Articles in Entire DC Network
Development Of Fertilizer Coatings From Polyglyoxylate-Polyester Blends Responsive To Root-Driven Ph Change., Spencer M Heuchan, Bo Fan, Jessica J Kowalski, Elizabeth R Gillies, Hugh A L Henry
Development Of Fertilizer Coatings From Polyglyoxylate-Polyester Blends Responsive To Root-Driven Ph Change., Spencer M Heuchan, Bo Fan, Jessica J Kowalski, Elizabeth R Gillies, Hugh A L Henry
Chemistry Publications
Many current controlled-release fertilizers (CRFs) are coated with nonbiodegradable polymers that can contribute to microplastic pollution. Here, coatings of self-immolative poly(ethyl glyoxylate) (PEtG) capped with a carbamate and blended with polycaprolactone (PCL) or poly(l-lactic acid) (PLA) were evaluated. They were designed to depolymerize and release fertilizers in the vicinity of plant roots, where the pH is lower than that in the surrounding environment. PEtG/PCL coatings exhibited significant temperature and pH effects, requiring 18 days at pH 5 and 30 °C, compared to 77 days at pH 7 and 22 °C, to reach 15% mass loss. Plant roots were also effective …
Charging And Supercharging Of Proteins For Mass Spectrometry: Recent Insights Into The Mechanisms Of Electrospray Ionization., Lars Konermann, Haidy Metwally, Quentin Duez, Insa Peters
Charging And Supercharging Of Proteins For Mass Spectrometry: Recent Insights Into The Mechanisms Of Electrospray Ionization., Lars Konermann, Haidy Metwally, Quentin Duez, Insa Peters
Chemistry Publications
Electrospray ionization (ESI) is an essential technique for transferring proteins from solution into the gas phase for mass spectrometry and ion mobility spectrometry. The mechanisms whereby [M + zH]z+ protein ions are released from charged nanodroplets during ESI have been controversial for many years. Here we discuss recent computational and experimental studies that have shed light on many of the mysteries in this area. Four types of protein ESI experiments can be distinguished, each of which appears to be associated with a specific mechanism. (i) Native ESI proceeds according to the charged residue model (CRM) that entails droplet evaporation …
Altering The Optoelectronic Properties Of Boron Difluoride Formazanate Dyes Via Conjugation With Platinum(Ii)-Acetylides, Jasveer S. Dhindsa, Adyn Melenbacher, Stephanie M. Barbon, Martin J. Stillman, Joe Gilroy
Altering The Optoelectronic Properties Of Boron Difluoride Formazanate Dyes Via Conjugation With Platinum(Ii)-Acetylides, Jasveer S. Dhindsa, Adyn Melenbacher, Stephanie M. Barbon, Martin J. Stillman, Joe Gilroy
Chemistry Publications
The combination of π-conjugated organic compounds and Pt(II)-acetylides is a powerful strategy for the production of functional optoelectronic materials. The presence of the heavy element, Pt, in these compounds enhances electronic delocalization generally resulting in low-energy absorption and emission maxima and often leads to intersystem crossing, resulting in phosphorescence. When boron complexes of N-donor ligands, such as boron dipyrromethenes (BODIPYs), are involved the molecular and polymeric materials produced have properties that are advantageous for their use as oxygen-sensors, in triplet–triplet annihilation, and as the functional components of photovoltaics. Based on these exciting results, we endeavored to thoroughly examine the effect …
In Search Of The Hot Spot., Danielle M Mcrae, François Lagugné-Labarthet
In Search Of The Hot Spot., Danielle M Mcrae, François Lagugné-Labarthet
Chemistry Publications
Tip-enhanced spectroscopy and its Raman variant, tip-enhanced Raman spectroscopy (TERS), provide the possibility to spatially resolve the vibrations of a single molecule when combined with ultra-high vacuum technology, but this technique suffers from poor time resolution2,3. On the other hand, surface-enhanced Raman spectroscopy (SERS) is a more common technique, and is used for many imaging and bioanalytical applications, still with single molecule sensitivity but, unlike TERS, without spatially resolved molecular imaging capabilities4. In SERS, the roughness and geometric characteristics of metallic surfaces (in general Al, Ag or Au) are exploited to enable high spatial …
Carving Plasmon Modes In Silver Sierpiński Fractals, Isobel C. Bicket, Edson P. Bellido, Danielle M. Mcrae, Francois Lagugne-Labarthet, Gianluigi A. Botton
Carving Plasmon Modes In Silver Sierpiński Fractals, Isobel C. Bicket, Edson P. Bellido, Danielle M. Mcrae, Francois Lagugne-Labarthet, Gianluigi A. Botton
Chemistry Publications
The surface plasmon resonance (SPR) modes of the first three generations of a Sierpiński fractal triangle are investigated using electron energy loss spectroscopy (EELS) complemented with finite difference time domain simulations. The Sierpiński fractal geometry is created in a subtractive manner, by carving triangular apertures into the triangular prism of the previous fractal generation. The ability of the fractal antenna to efficiently utilize space in coupling to long wavelength excitations is confirmed on the single nanostructure level via redshifting of the primary dipole mode as the fractal generation is increased. Through application of the Babinet principle, it is demonstrated that …
Synthesis Of Functionalized Tetrahydropyridines By Sncl4-Mediated [4+2] Cycloaddition Between Donor–Acceptor Cyclobutanes And Nitriles, David Tong, Jackie Wu, Nathan Bazinski, Donghyun Koo, Naresh Vemula, Brian Pagenkopf
Synthesis Of Functionalized Tetrahydropyridines By Sncl4-Mediated [4+2] Cycloaddition Between Donor–Acceptor Cyclobutanes And Nitriles, David Tong, Jackie Wu, Nathan Bazinski, Donghyun Koo, Naresh Vemula, Brian Pagenkopf
Chemistry Publications
Cycloadditions of strained carbocycles promoted by Lewis acids are powerful methods to construct heterocyclic frameworks. In fact, the formal [3+2] cycloadditions of donor-acceptor (DA) cyclopropanes with nitriles has seen particular success in synthesis. In this work, we report on the first [4+2] cycloaddition of nitriles with DA cyclobutanes via Lewis acid activation. Tetrahydropyridine derivatives were obtained in up to 91% yield from various aryl activated cyclobutane diesters and aliphatic or aromatic nitriles.
Testing The Robustness Of Solution Force Fields For Md Simulations On Gaseous Protein Ions., Justin H Lee, Katja Pollert, Lars Konermann
Testing The Robustness Of Solution Force Fields For Md Simulations On Gaseous Protein Ions., Justin H Lee, Katja Pollert, Lars Konermann
Chemistry Publications
It is believed that electrosprayed proteins and protein complexes can retain solution-like conformations in the gas phase. However, the lack of high-resolution structure determination methods for gaseous protein ions implies that their properties remain poorly understood. Many practitioners tackle this difficulty by complementing mass spectrometry-based experiments with molecular dynamics (MD) simulations. It is a potential problem that the standard MD force fields used for this purpose (such as OPLS-AA/L and CHARMM) were optimized for solution conditions. The question whether these force fields produce meaningful gas-phase data has received surprisingly little attention. Standard force fields are overpolarized to account for an …
What Is The Accuracy Limit Of Adiabatic Linear-Response Tddft Using Exact Exchange–Correlation Potentials And Approximate Kernels?, Jaspreet Kaur, Egor Ospadov, Viktor N. Staroverov
What Is The Accuracy Limit Of Adiabatic Linear-Response Tddft Using Exact Exchange–Correlation Potentials And Approximate Kernels?, Jaspreet Kaur, Egor Ospadov, Viktor N. Staroverov
Chemistry Publications
Calculation of vertical excitation energies by the adiabatic linear-response time-dependent density-functional theory (TDDFT) requires static Kohn–Sham potentials and exchange–correlation kernels. When these quantities are derived from standard density-functional approximations (DFA), mean absolute errors (MAE) of the method are known to range from 0.2 eV to over 1 eV, depending on the functional and type of excitation. We investigate how the performance of TDDFT varies when increasingly accurate exchange–correlation potentials derived from Hartree–Fock (HF) and post-HF wavefunctions are combined with different approximate kernels. The lowest MAEs obtained in this manner for valence excitations are about 0.15–0.2 eV, which appears to be …
Probing Mid-Infrared Plasmon Resonances In Extended Radial Fractal Structures., Gregory Q Wallace, Danielle M Mcrae, François Lagugné-Labarthet
Probing Mid-Infrared Plasmon Resonances In Extended Radial Fractal Structures., Gregory Q Wallace, Danielle M Mcrae, François Lagugné-Labarthet
Chemistry Publications
Infrared (IR) antennas made of metallic nanostructures are widely tunable from the near- to the far-IR range. They can be utilized for a variety of applications such as light harvesting and photonic filters, and their structural linear or circular anisotropy can be exploited to further enhance the sensitivity of spectroscopic measurements. Here gold dendritic fractal structures that were optimized to exhibit multiple resonances in the mid-IR range were characterized using a scattering-type scanning near-field optical IR microscope. The spatially resolved IR maps associated with the individual modes serve as a basis to understand the mode evolution between each fractal generation.
Poly(Ester Amide) Particles For Controlled Delivery Of Celecoxib., Ian J Villamagna, Trent N Gordon, Mark B Hurtig, Frank Beier, Elizabeth R Gillies
Poly(Ester Amide) Particles For Controlled Delivery Of Celecoxib., Ian J Villamagna, Trent N Gordon, Mark B Hurtig, Frank Beier, Elizabeth R Gillies
Chemistry Publications
Many potential pharmacological treatments for osteoarthritis can result in undesirable side effects due to the systemic administration of drugs, making the direct delivery of drugs to joints an attractive alternative. Poly(ester amide)s (PEAs) have been shown to exhibit promising properties for the development of particle-based intra-articular delivery vehicles. However, a limited range of PEA structures has been investigated. In this study, we prepared and characterized the properties of two different PEA particles composed of l-phenylalanine, sebacic acid, and either 1,4-butanediol or 1,8-octanediol (PBSe and POSe, respectively). The anti-inflammatory drug celecoxib (CXB) was encapsulated into the particles. Despite minor structural differences, …
Oxoborane Formation Turns On Formazanate-Based Photoluminescence, Ryan R. Maar, Nicholas A. Hoffman, Viktor N. Staroverov, Joe Gilroy
Oxoborane Formation Turns On Formazanate-Based Photoluminescence, Ryan R. Maar, Nicholas A. Hoffman, Viktor N. Staroverov, Joe Gilroy
Chemistry Publications
The synthesis of compounds containing multiple bonds to boron has challenged main-group chemists for decades. Despite significant progress, the possibility that the formation of such bonds can turn on photoluminescence has received minimal attention. We report an oxoborane (B=O) complex that is electronically stabilized by a formazanate ligand in the absence of significant steric bulk and, unlike the common BX2 (X = F, Cl) formazanate adducts, exhibits intense photoluminescence. The latter property was rationalized through density-functional calculations which indicated that the B=O bond enhances photoluminescence by drastically reducing differences between the ligand's geometries in the ground and excited states. …
Mechanism Of Electrospray Supercharging For Unfolded Proteins: Solvent-Mediated Stabilization Of Protonated Sites During Chain Ejection., Insa Peters, Haidy Metwally, Lars Konermann
Mechanism Of Electrospray Supercharging For Unfolded Proteins: Solvent-Mediated Stabilization Of Protonated Sites During Chain Ejection., Insa Peters, Haidy Metwally, Lars Konermann
Chemistry Publications
Proteins that are unfolded in solution produce higher charge states during electrospray ionization (ESI) than their natively folded counterparts. Protein charge states can be further increased by the addition of supercharging agents (SCAs) such as sulfolane. The mechanism whereby these supercharged [M + zH] z+ ions are formed under unfolded conditions remains unclear. Here we employed a combination of mass spectrometry (MS), ion mobility spectrometry (IMS), and molecular dynamics (MD) simulations for probing the ESI mechanism under denatured supercharging conditions. ESI of acid-unfolded apo-myoglobin (aMb) in the presence of sulfolane produced charge states around 27+, all the way to fully …
Optoelectronic, Aggregation, And Redox Properties Of Double-Rotor Boron Difluoride Hydrazone Dyes, Daniela Cappello, Denis A.B. Therien, Viktor N. Staroverov, Francois Lagugne-Labarthet, Joe Gilroy
Optoelectronic, Aggregation, And Redox Properties Of Double-Rotor Boron Difluoride Hydrazone Dyes, Daniela Cappello, Denis A.B. Therien, Viktor N. Staroverov, Francois Lagugne-Labarthet, Joe Gilroy
Chemistry Publications
We develop the chemistry of boron difluoride hydrazone dyes (BODIHYs) bearing two aryl substituents and explore their properties. The low-energy absorption bands (λmax = 427–464 nm) of these dyes depend on the nature of the N-aryl groups appended to the BODIHY framework. Electron-donating and extended p-conjugated groups cause a red shift, whereas electron-withdrawing groups result in a blue shift. The title compounds were weakly photoluminescent in solution and strongly photoluminescent as thin films (λPL = 525–578 nm) with quantum yields of up to 18% and lifetimes of 1.1–1.7 ns, consistent with the dominant radiative decay through fluorescence. …
Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann
Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann
Chemistry Publications
Experiments and molecular dynamics (MD) simulations in the literature indicate that gaseous proteins generated by electrospray ionization (ESI) can retain native-like structures. However, the exact properties of these ions remain to be explored. Focusing on ubiquitin and lysozyme, we examined several pertinent questions. (1) We applied solvent MD runs to test whether the X-ray structures of both proteins are affected by crystal packing. Main and side-chain orientations were retained in solution, providing a justification for the hitherto unscrutinized approach of relying on crystal data for "solution" versus gas-phase comparisons. (2) Most earlier gas-phase protein MD investigations employed short (ns) simulation …
Effect Of Drug Loading On The Properties Of Temperature-Responsive Polyester-Poly(Ethylene Glycol)-Polyester Hydrogels, D. Andrew Prince, Ian J. Villamagna, Cameron C. Hopkins, John R. De Bruyn, Elizabeth R. Gillies
Effect Of Drug Loading On The Properties Of Temperature-Responsive Polyester-Poly(Ethylene Glycol)-Polyester Hydrogels, D. Andrew Prince, Ian J. Villamagna, Cameron C. Hopkins, John R. De Bruyn, Elizabeth R. Gillies
Chemistry Publications
Hydrogels that can undergo gelation upon injection in vivo are promising systems for the site-specific delivery of drugs. In particular, some thermo-responsive gels require no chemical additives but simply gel in response to a change from a lower temperature to physiological temperature (37 °C). The gelation mechanism does not involve covalent bonds, and it is possible that incorporation of drugs into the hydrogel could disrupt gelation. We investigated the incorporation of drugs into thermo-responsive hydrogels based on poly(ϵ-caprolactone-co-lactide)-block-poly(ethylene glycol)-block-poly(ϵ-caprolactone-co-lactide) (PCLA–PEG–PCLA). Significant differences in properties and in the response …
Triggering Depolymerization: Progress And Opportunities For Self-Immolative Polymers, Rebecca Yardley, Amir Rabiee Kenaree, Elizabeth Gillies
Triggering Depolymerization: Progress And Opportunities For Self-Immolative Polymers, Rebecca Yardley, Amir Rabiee Kenaree, Elizabeth Gillies
Chemistry Publications
Polymers that depolymerize end-to-end upon cleavage of their backbones or end-caps, often referred to as “self-immolative” polymers (SIPs), have garnered significant interest in recent years. They can be distinguished from other degradable and stimuli-responsive polymers by their ability to provide amplified responses to stimuli, as a single bond cleavage event is translated into the release of many small molecules through a cascade of reactions. Here, the synthesis and properties of the major classes of SIPs including poly(benzyl carbamate)s, poly(benzyl carbonate)s, polyphthalaldehydes, polyglyoxylates, polyglyoxylamides, poly(olefin sulfone)s, and poly(benzyl ether)s are presented. In addition, their advantages and limitations as well as their …
Thermo-Responsive And Covalently Cross-Linkable Hydrogels For Intra-Articular Drug Delivery, Andy Prince, Ian J. Villamagna, Aneta Borecki, Frank Beier, John R. De Bruyn, Mark Hurtig, Elizabeth Gillies
Thermo-Responsive And Covalently Cross-Linkable Hydrogels For Intra-Articular Drug Delivery, Andy Prince, Ian J. Villamagna, Aneta Borecki, Frank Beier, John R. De Bruyn, Mark Hurtig, Elizabeth Gillies
Chemistry Publications
The local delivery of drugs to joints is a recognized strategy in the treatment of osteoarthritis. Hydrogels, particularly those that can be injected as liquids but undergo gelation in the joint, are promising platforms for intra-articular drug delivery. However, their properties must be carefully designed and tuned to achieve sustained drug release, which has been a challenge with previous hydrogels. We describe here the use of a combination of non-covalent thermal gelation and covalent cross-linking with poly(caprolactone-co-lactide)(PCLA)-poly(ethylene glycol)(PEG)-PCLA triblock copolymers to achieve hydrogels with sustained drug release in joints. The hybrid cross-linking approach afforded higher viscoelastic and compression …
Polyglyoxylamides: Tuning Structure And Properties Of Self- Immolative Polymers, Quinton E.A. Sirianni, Amir Rabiee Kenaree, Elizabeth Gillies
Polyglyoxylamides: Tuning Structure And Properties Of Self- Immolative Polymers, Quinton E.A. Sirianni, Amir Rabiee Kenaree, Elizabeth Gillies
Chemistry Publications
Self-immolative polymers (SIPs) are a class of stimuli-responsive materials that undergo controlled end-to-end depolymerization in response to stimuli. Their unique degradation and amplification properties have made them of interest for a diverse array of applications including sensors, vehicles for controlled release, and transient objects. Thus far, a limited number of SIP backbones exists, each with its own advantages and limitations. We report here the preparation and study of polyglyoxylamides (PGAms) as a new class of SIPs. PGAms were synthesized by simple post-polymerization modifications of poly(ethyl glyoxylate) (PEtG). While retaining the important stimuli-responsive depolymerization properties of polyglyoxylates, PGAms exhibited much different …
Fabrication And In-Situ Cross-Linking Of Carboxylic Acid-Functionalized Poly(Ester Amide) Scaffolds For Tissue Engineering, Kai Cao, Derek S. Flegg, Shigang Lin, Francois Lagugne-Labarthet, Kibret Mequanint, Elizabeth Gillies
Fabrication And In-Situ Cross-Linking Of Carboxylic Acid-Functionalized Poly(Ester Amide) Scaffolds For Tissue Engineering, Kai Cao, Derek S. Flegg, Shigang Lin, Francois Lagugne-Labarthet, Kibret Mequanint, Elizabeth Gillies
Chemistry Publications
Three-dimensional (3D) scaffolds are important tools for tissue engineering, and should ideally provide both biochemical cues and biomechanical support for cells. Poly(ester amide)s (PEAs) have emerged as promising materials for the preparation of tissue engineering scaffolds and the pendant side chains of residues such as ʟ-lysine and ʟ-aspartic acid can provide sites for the conjugation of biochemical signals. However, it has been challenging to combine scaffold morphological stability with the presentation of reactive groups on PEA scaffolds. We describe here a new approach involving the functionalization of a ʟ-lysine-containing PEA with maleic anhydride to simultaneously introduce cross-linkable alkenes and carboxylic …