A5061663827- Crystallization and Solubility Studies
- CO2 Reduction Techniques and Catalysts
- X-ray Diffraction in Crystallography
- Spectroscopy and Quantum Chemical Studies
- Organometallic Complex Synthesis and Catalysis
- Protein Structure and Dynamics
- Spectroscopy Techniques in Biomedical and Chemical Research
- Oxidative Organic Chemistry Reactions
- Radical Photochemical Reactions
- Photochemistry and Electron Transfer Studies
- Metal-Catalyzed Oxygenation Mechanisms
- Magnetism in coordination complexes
- Protein purification and stability
- Catalysis and Oxidation Reactions
- Crystallography and molecular interactions
- Analytical Chemistry and Chromatography
- Spectroscopy and Chemometric Analyses
- Photoreceptor and optogenetics research
- Alzheimer's disease research and treatments
- Molecular spectroscopy and chirality
- Electrocatalysts for Energy Conversion
- Fluorine in Organic Chemistry
- Advanced biosensing and bioanalysis techniques
- Listeria monocytogenes in Food Safety
- Viral Infectious Diseases and Gene Expression in Insects
Merck & Co., Inc., Rahway, NJ, USA (United States)
2023-2025
United States Military Academy
2021-2025
University of Wisconsin–Madison
2017-2020
University of California, Berkeley
2012-2018
Madison Group (United States)
2017
Lawrence Berkeley National Laboratory
2012-2014
Studying the local solvent surrounding nanoparticles is important to understanding energy exchange dynamics between particles and their environment, there a need for spectroscopic methods that can dynamically probe region in nearby contact with nanoparticles. In this work, we demonstrate use of time-resolved infrared spectroscopy track changes vibrational mode water on time scale hundreds picoseconds, revealing heat transfer from gold nanorods environment. We applied prototypical plasmonic...
We report the transition dipole strengths and frequencies of amyloid β-sheet amide I mode for aggregated proteins amyloid-β1–40, calcitonin, α-synuclein, glucagon. According to standard vibrational coupling models proteins, canonical β-sheets are set by their size structural environmental disorder, which determines delocalization length excitons. The larger lower frequency main infrared-allowed transition, A⊥. also predict an accompanying increase in strength. For measured here, we find no...
Transiently populated oligomers formed en route to amyloid fibrils may constitute the most toxic aggregates associated with many amyloid-associated diseases. Most nucleation theories used describe aggregation predict low oligomer concentrations and do not take into account free energy costs that be structural rearrangements between fiber states. We have isotope labeling two-dimensional infrared spectroscopy spectrally resolve an oligomeric intermediate during of human islet protein (hIAPP or...
We use two-dimensional IR (2D IR) spectroscopy to explore fibril formation for the two predominant isoforms of β-amyloid (Aβ1-40 and Aβ1-42) protein associated with Alzheimer's disease. Two-dimensional spectra resolve a transition at 1610 cm–1 in Aβ fibrils that does not appear other aggregates, even those predominantly β-sheet-structure-like oligomers. This is resolved linear because it lies under broad band centered 1625 cm–1, which traditional infrared signature amyloid fibrils. The...
Caught in the light: The fulvalene diruthenium complex shown on left side of picture captures sun light, causing initial Ru-Ru bond rupture to furnish a long-lived triplet biradical syn configuration. This species requires thermal activation reach crossing point (middle) into singlet manifold route its storage isomer right through anti biradical.
Human islet amyloid polypeptide (hIAPP) aggregates into fibrils through oligomers that have been postulated to contain α-helices as well β-sheets.
Abstract A study of the scope and limitations varying ligand framework around dinuclear core FvRu 2 in its function as a molecular solar thermal energy storage is presented. It includes DFT calculations probing effect substituents, other metals, CO exchange for ligands on Δ H . Experimentally, system shown to be robust much it tolerates number variations, except identity metal certain substitution patterns. Failures include 1,1′,3,3′‐tetra‐ tert ‐butyl ( 4 ), 1,2,2′,3′‐tetraphenyl 9 diiron...
ConspectusThe importance of spin state changes in organometallic reactions is a topic significant interest, as an increasing number reaction mechanisms involving are consistently being uncovered. The potential influence on rates can be difficult to predict, and thus this class remains among the least well understood chemistry. Ultrafast time-resolved infrared (TRIR) spectroscopy provides powerful tool for probing dynamics catalysis, such processes often occur picosecond nanosecond time scale...
Raman spectroscopy is a powerful method for analyzing chemical compositions across diverse samples. Spontaneous scattering (spRS) provides complete spectra but typically yields low signal levels, requiring long integration times. In contrast, stimulat-ed (SRS) produces much stronger signals, allowing rapid spectral acquisition, and has been widely used to accelerate imaging. Despite advances in both techniques, it remains unclear which offers superior limits of detection (LODs) molecules...
Raman spectroscopy is a powerful method for analyzing chemical compositions across diverse samples. Spontaneous scattering (spRS) provides complete spectra but typically yields low signal levels, requiring long integration times. In contrast, stimulat-ed (SRS) produces much stronger signals, allowing rapid spectral acquisition, and has been widely used to accelerate imaging. Despite advances in both techniques, it remains unclear which offers superior limits of detection (LODs) molecules...
Abstract Recombinant proteins are critical for modern therapeutics and diagnostics, with Chinese hamster ovary (CHO) cells serving as the primary production platform. However, environmental chemical stressors in bioreactors often trigger cell death, particularly apoptosis, posing a significant challenge to recombinant protein manufacturing. Rapid, label-free methods monitor death essential ensuring better quality. Stimulated Raman scattering (SRS) microscopy offers powerful, approach measure...
We report the observation of a solvent-dependent spin state equilibrium in 16-electron photoproduct CpCo(CO). Time-resolved infrared spectroscopy has been used to observe concurrent formation two distinct solvated monocarbonyl photoproducts, both which arise from same triplet CpCo(CO) precursor. Experiments different solvent environments, combined with electronic structure theory calculations, allow us assign photoproducts singlet and CpCo(CO)(solvent) complexes. These results add our...
The (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical (TEMPO) has been employed for an extensive range of chemical applications, ranging from organometallic catalysis to serving as a structural probe in biological systems. As ligand complex, TEMPO can exhibit several distinct coordination modes. Here we use ultrafast time-resolved infrared spectroscopy study the reactivity toward coordinatively unsaturated 16- and 17-electron reaction intermediates. coordinates metal centers 16-electron...
Spectroscopic techniques that are capable of measuring surfaces and interfaces must overcome two technical challenges: one, the low coverage molecules at surface, two, discerning between signals from bulk surface. We present surface enhanced attenuated reflection 2D infrared (SEAR IR) spectroscopy, a method combines localized plasmons with pump-probe geometry to achieve monolayer sensitivity. The is demonstrated 6 µm amide I band model peptide, cysteine terminated α-helical peptide tethered...
Picosecond time-resolved infrared spectroscopy (TRIR) was performed for the first time on a dithiolate bridged binuclear iron(I) hexacarbonyl complex ([Fe2(μ-bdt)(CO)6], bdt = benzene-1,2-dithiolate) which is structural mimic of active site [FeFe]-hydrogenase enzyme. As these model sites are increasingly being studied their potential in photocatalytic systems hydrogen production, understanding excited and ground state dynamics critical. In n-heptane, absorption 400 nm light causes carbonyl...
The picosecond dynamics of CpCo(CO), a catalytic intermediate in the cyclotrimerization alkynes, have been studied using time-resolved infrared spectroscopy and density functional theory calculations. In neat 1-hexyne or 1-hexene solution, first to form is triplet η2-coordinated species, which then converts singlet η2 species ca. 30–40 ps. only solvent-coordinated observed at early times, suggesting that this dominant mechanistic pathway for coordination alkynes alkenes CpCo(CO) catalyst....
Adjuvants are commonly employed to enhance the efficacy of a vaccine and thereby increase resulting immune response in patient. The activity effectiveness emulsion-based adjuvants has been heavily studied throughout pharmaceuticals; however, there exists lack research which monitors formation stable emulsion real time. Process analytical technology (PAT) provides solution meet this need. PAT involves collection situ data, providing time information about monitored process as well increasing...
There is enormous interest in measuring amyloid fibril structures, but most structural studies measure formation vitro using aqueous buffer. Ideally, one would like to structure and mechanism under more physiological conditions. Toward this end, we have developed a method for studying human serum. Our approach uses isotope labeling, antibody depletion of the abundant proteins (albumin IgG), infrared spectroscopy aggregation serum with reduced protein content. Reducing nonamyloid content...
Acetyl phosphate salts are common donors for enzymatic phosphorylation with kinases and used in a variety of industrial biocatalytic processes. Due to their ever-increasing demand, synthesis high-quality acetyl is critical pharmaceutical process development, especially given that impurities such as acetic acid can inhibit the intended reaction. Current offline analytical methodologies investigating reagent quality limited due hydrolytically unstable nature chemical species, resulting its...