Physical Sciences and Mathematics Commons^™

Synthesis Of A Model Of The Bc Ring System Of Oxygenated Angucyclines, Xiaolan Wu, Abdullah Allaoa, Tony E. Nicolas

Publications and Research

Angucycline is a subclass of natural antibiotics, containing a characteristic tetracyclic ring structure, and featuring a wide range of biological functions, including antitumor, antiviral and antifungal properties. This extraordinarily therapeutic character has interested many chemists to develop efficient methodologies for synthesizing the tetracyclic ring system of angucycline. Construction of the BC ring configuration appears as a synthetic challenge. Successful installation of hydroxyl groups at the AB junction would pave the way for efficient syntheses. As a continuation of the previous work done on this system, our synthetic methodology focuses on the coupling of a suitably substituted Phthalide and an activated …

Pretargeting Of Internalizing Trastuzumab And Cetuximab With A 18f-Tetrazine Tracer In Xenograft Models, Outi Keinänen, Kimberly Fung, Jacob Pourat, Vilma Jallinoja, Delphine Vivier, Nagavara Kishore Pillarsetty, Anu J. Airaksinen, Jason S. Lewis, Brian M. Zeglis, Mirkka Sarparanta

Publications and Research

Background: Pretargeting-based approaches are being investigated for radioimmunoimaging and therapy applications to reduce the effective radiation burden to the patient. To date, only a few studies have used short-lived radioisotopes for pretargeting of antibodies, and such examples with internalizing antibodies are even rarer. Herein, we have investigated pretargeting methodology using inverse electron-demand Diels-Alder (IEDDA) for tracing two clinically relevant, internalizing monoclonal antibodies, cetuximab and trastuzumab.

Results: Bioorthogonal reaction between tetrazine and trans-cyclooctene (TCO) was used for tracing cetuximab and trastuzumab in vivo with a fluorine-18 (t½ = 109.8 min) labelled tracer. TCO-cetuximab or TCO-trastuzumab was administered 24, 48, or 72 …

The Role Of Carbon On Copper–Carbon Composites For The Electrooxidation Of Alcohols In An Alkaline Medium, Leticia García-Cruz, Conchi O. Ania, Ana Paula Carvalho, Teresa Bandosz, Vicente Montiel, Jesús Iniesta

Publications and Research

Copper–carbon composites were prepared following various different synthetic routes and using various carbon precursors (i.e., lignocellulose and graphite oxide), andwere used as electrocatalysts for the oxidation of propargyl alcohol (PGA) in an alkaline medium. The electrochemical response of the copper-based catalysts was analyzed in terms of the influence of the metallic species, the carbon matrix incorporated in the composites, and the chemical structure of the ionomers—Nafion and poly (4-vinylpyridine) cross-linked methyl chloride quaternary salt resin (4VP)—used in the fabrication of the electrodes. Data has shown that the incorporation of reduced graphene oxide sheets between the copper metallic particles increased the …

Efficient Air Desulfurization Catalysts Derived From Pig Manure Liquefaction Char, Rajiv Wallace, Sundaramurthy Suresh, Elham H. Fini, Teresa Bandosz

Publications and Research

Biochar from the liquefaction of pig manure was used as a precursor of H2S desulfurization adsorbents. In its inorganic matter, it contains marked quantities of calcium, magnesium and iron, which are known as hydrogen sulfide oxidation catalysts. The char was used either as-received or mixed with 10% nanographite. The latter was added to increase both the content of the carbon phase and conductivity. ZnCl2 in two different ratios of char to an activation agent (1:1 and 1:2) was used to create the porosity in the carbon phase. The content of the later was between 18–45%. The activated samples adsorbed 144 …

Synthesis, Crystal Structure, And Photoluminescent Properties Of 3,3′,4,4′-Tetraethyl-5,5′-Divinyl-2,2′-Bipyrrole Derivatives, Toru Okawara, Reo Kawano, Hiroya Morita, Alan Finkelstein, Renjiro Toyofuku, Kanako Matsumoto, Kenji Takehara, Toshihiko Nagamura, Seiji Iwasa, Sanjai Kumar

Publications and Research

Photoluminescent divinylbipyrroles were synthesized from 3,3′,4,4′-tetraetyl-2,2′-bipyrrole-5,5′-dicarboxaldehyde and activated methylene compounds via aldol condensation.For mechanistic clarity, molecular structures of Meldrum’s acid- and 1,3-dimethylbarbituricacid-derived divinylbipyrroles were determined by single-crystal X-ray diffraction. Photoluminescentproperties of the synthesized divinylbipyrroles in dichloromethane were found to be dependent onthe presence of electron withdrawing groups at the vinylic terminal. The divinylbipyrroles derivedfrom malononitrile, Meldrum’s acid, and 1,3-dimethylbarbituric acid showed fluorescent peaks at553, 576, and 602 nm respectively. Computational studies indicated that the alkyl substituents on thebipyrrole 3 and 3′positions increased energy level of the highest occupied molecular orbital (HOMO)compared to the unsubstituted derivatives and provided rationale for the …

Ligand Modulation Of Sidechain Dynamics In A Wild-Type Human Gpcr, Lindsay D. Clark, Igor Dikiy, Karen Chapman, Karin Ej Rodstrom, James Aramini, Michael V. Levine, George Khelashvili, Soren Gf Rasmussen, Kevin H. Gardner, Daniel M. Rosenbaum

Publications and Research

GPCRs regulate all aspects of human physiology, and biophysical studies have deepened our understanding of GPCR conformational regulation by different ligands. Yet there is no experimental evidence for how sidechain dynamics control allosteric transitions between GPCR conformations. To address this deficit, we generated samples of a wild-type GPCR (A2AR) that are deuterated apart from 1H/13C NMR probes at isoleucine d1 methyl groups, which facilitated 1H/13C methyl TROSY NMR measurements with opposing ligands. Our data indicate that low [Na+] is required to allow large agonist-induced structural changes in A2AR, and that patterns of sidechain dynamics substantially differ between agonist (NECA) and …

The Effect Of Hydrogen Bonding In Enhancing The Ionic Affinities Of Immobilized Monoprotic Phosphate Ligands, Spiro D. Alexandratos, Xiaoping Liu

Publications and Research

Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intra-ligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greater …

Chelator-Free Radiolabeling Of Serrs Nanoparticles For Whole-Body Pet And Intraoperative Raman Imaging, Matthew A. Wall, Travis Shaffer, Stefan Harmsen, Darjus-Felix Tschaharganeh, Chun-Hao Huang, Scott W. Lowe, Charles Michael Drain, Moritz F. Kircher

Publications and Research

A single contrast agent that offers whole-body non-invasive imaging along with the superior sensitivity and spatial resolution of surface-enhanced resonance Raman scattering (SERRS) imaging would allow both pre-operative mapping and intraoperative imaging and thus be highly desirable. We hypothesized that labeling our recently reported ultrabright SERRS nanoparticles with a suitable radiotracer would enable pre-operative identification of regions of interest with whole body imaging that can be rapidly corroborated with a Raman imaging device or handheld Raman scanner in order to provide high precision guidance during surgical procedures. Here we present a straightforward new method that produces radiolabeled SERRS nanoparticles for …

Distinct Properties Of The Triplet Pair State From Singlet Fission, M. Tuan Trinh, Andrew Pinkard, Andrew B. Pun, Samuel N. Sanders, Elango Kumarasamy, Matthew Y. Sfeir, Luis M. Campos, Xavier Roy, X.-Y. Zhu

Publications and Research

Singlet fission, the conversion of a singlet exciton (S₁) to two triplets (2 × T₁), may increase the solar energy conversion efficiency beyond the Shockley-Queisser limit. This process is believed to involve the correlated triplet pair state ¹(TT). Despite extensive research, the nature of the ¹(TT) state and its spectroscopic signature remain actively debated. We use an end-connected pentacene dimer (BP0) as a model system and show evidence for a tightly bound ¹(TT) state. It is characterized in the near-infrared (IR) region (~1.0 eV) by a distinct excited-state absorption (ESA) spectral feature, which …

Cross-Dehydrogenative Coupling And Oxidativeamination Reactions Of Ethers And Alcohols With Aromatics And Heteroaromatics, Mahesh K. Lakshman, Prasanna K. Vuram

Publications and Research

Cross-dehydrogenative coupling (CDC) is a process in which, typically, a C–C bond is formed at the expense of two C–H bonds, either catalyzed by metals or other organic compounds, or via uncatalyzed processes. In this perspective, we present various modes of C–H bond-activation at sp3 centers adjacent to ether oxygen atoms, followed by C–C bond formation with aromatic systems as well as with heteroaromatic systems. C–N bond-formation with NH-containing heteroaromatics, leading to hemiaminal ethers, is also an event that can occur analogously to C–C bond formation, but at the expense of C–H and N–H bonds. A large variety of hemiaminal …

Species Identification Of Necrophagous Insect Eggs Based On Amino Acid Profile Differences Revealed By Direct Analysis In Real Time-High Resolution Mass Spectrometry, Justine E. Giffen, Jennifer Y. Rosati, Cameron M. Longo, Rabi A. Musah

Publications and Research

The colonization of decomposing remains by necrophagous insects such as blow flies is of forensic importance because the progression through the various stages of insect development can be correlated to time of death. The ability to infer this information hinges on accurate determination of the fly species that are associated with the entomological evidence collected. This evidence can include eggs, larvae, pupae, and puparial casings. Determination of the egg’s identity is particularly challenging because the eggs of multiple species are morphologically very similar. We report here that the species identity of fly eggs can be determined from their chemical fingerprint …

Cancer Cell Spheroids Are A Better Screen For The Photodynamic Efficiency Of Glycosylated Photosensitizers, Patrícia M. R. Pereira, Naxhije Berisha, N.V.S. Dinesh K. Bhupathiraju, Rosa Fernandes, João P.C. Tomé, Charles Michael Drain

Publications and Research

Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intraligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greater …

29si Nmr And Saxs Investigation Of The Hybrid Organic-Inorganic Glasses Obtained By Consolidation Of The Melting Gels, Andrei Jitianu, Sylvian Cadars, Fan Zhang, Gabriela Rodriguez, Quentin Picard, Mario Aparicio, Jadra Mosa, Lisa C. Klein

Publications and Research

This study is focused on structural characterization of hybrid glasses obtained by consolidation of melting gels. The melting gels were prepared in molar ratios of methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES) of 75%MTES-25%DMDES and 65%MTES-35%DMDES. Following consolidation, the hybrid glasses were characterized using Raman, ²⁹Si and ¹³C Nuclear Magnetic Resonance (NMR) spectroscopies, synchrotron Small Angle X-Ray Scattering (SAXS) and scanning electron microscopy (SEM). Raman spectroscopy revealed the presence of Si–C bonds in the hybrid glasses and 8-membered ring structures in the Si–O–Si network. Qualitative NMR spectroscopy identified the main molecular species, while quantitative NMR data showed that the ratio …

Thickness-Properties Synergy In Organic–Inorganic Consolidated Melting-Gel Coatings For Protection Of 304 Stainless Steel In Nacl Solutions, Mario Amapricio, Andrei Jitianu, Gabriela Rodriguez, Kutaiba Al-Marzoki, Mihaela Jitianu, Jadra Mosa, Lisa C. Klein

Publications and Research

Homogeneous and crack-free methyl-substituted organic–inorganic hybrid glass coatings (thickness up to 10 μm) were deposited on AISI 304 stainless steel. Different hybrid glasses obtained fromconsolidation of the diluted melting gels with various methyltriethoxysilane (MTES)/dimethyldiethoxysilane (DMDES) ratios were evaluated considering chemical structure, coating adhesion and corrosion protection. The 70MTES/30DMDES (molar%) melting-gel coating provided improved corrosion protection for this steel due to the synergy of different properties: a highly cross-linked inorganic structure, a coating plasticity based on the hybrid network, and a good adhesion to the substrate through hydroxyl groups. Electrochemical results showa good barrier film with a passive range of 500 …

Glass Polymorphism In Glycerol–Water Mixtures: I. A Computer Simulation Study, David A. Jahn, Jessina Wong, Johannes Bachler, Thomas Loerting, Nicolas Giovambattista

Publications and Research

We perform out-of-equilibrium molecular dynamics (MD) simulations of water–glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA–HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/ decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration wg = 0–13% and find that, for the …

A Computational Study Of Lithium Carbamate Synthetic Intermediate Structures And Aggregation, Lawrence M. Pratt

Publications and Research

Computational quantum chemistry was used to investigate the structures of lithium carbamates in the gas phase and in ethereal solvents. These compounds act as nucleophiles with either inversion or retention of configuration at the chiral center and knowledge of the aggregation state is the first step in understanding the reactivity. The sterically hindered lithium phenyl carbamate is calculated to exist largely as the ether or THF solvated monomer in solution. Higher aggregates are possible in the gas phase, which is often taken as an approximation for solutions in non-polar solvents.

Tuning The Polarity Of Charge Carriers Using Electron Deficient Thiophenes, Jonathan Z. Low, Brian Capozzi, Jing Cui, Sujun Wei, Latha Venkataraman, Luis M. Campos

Publications and Research

Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/ TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed …

Evolution Of Complex Target Selex To Identify Aptamers Against Mammalian Cell-Surface Antigens, Prabodhika R. Mallikaratchy

Publications and Research

The demand has increased for sophisticated molecular tools with improved detection limits. Such molecules should be simple in structure, yet stable enough for clinical applications. Nucleic acid aptamers (NAAs) represent a class of molecules able to meet this demand. In particular, aptamers, a class of small nucleic acid ligands that are composed of single-stranded modified/unmodified RNA/DNA molecules, can be evolved from a complex library using Systematic Evolution of Ligands by EXponential enrichment (SELEX) against almost any molecule. Since its introduction in 1990, in stages, SELEX technology has itself undergone several modifications, improving selection and broadening the repertoire of targets. This …

Circular Dichroistic Impacts Of 1‑(3-Dimethylaminopropyl)-3- Ethylurea: Secondary Structure Artifacts Arising From Bioconjugation Using 1‑Ethyl-3-[3-Dimethylaminopropyl]Carbodiimide, Matthew B. Kubilius, Raymond S. Tu

Publications and Research

1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide (EDC) is a commonly used reagent for bioconjugation and peptide synthesis. Both EDC and the corresponding urea derivative, 1-(3-dimethylaminopropyl)-3-ethylurea (EDU), are achiral. As the reagent is active in aqueous solutions, it is a common choice for the study of evolving secondary structural changes via circular dichroism. This work highlights the effect of EDU on spectropolarimetric measurements, namely, the problematic absorption profile at low wavelengths (190−220 nm). We demonstrate that EDU is capable of erroneously indicating structural changes, particularly loss of α-helical character, through masking of the characteristic minimum at 208 nm. However, if the concentrations of the EDU in …