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  • Undergraduate Poster Abstracts
  • Chemistry (Except Biochemistry)

    FRI-G46 DEVELOPMENT OF LIGANDS THAT TARGET NUCLEOTIDE MISMATCHES INVOLVED IN TRINUCLEOTIDE REPEAT DISEASES

    • Julio Serrano ;
    • Steven Zimmerman ;

    FRI-G46

    DEVELOPMENT OF LIGANDS THAT TARGET NUCLEOTIDE MISMATCHES INVOLVED IN TRINUCLEOTIDE REPEAT DISEASES

    Julio Serrano, Steven Zimmerman.

    University of Illinois at Urbana-Champaign, Urbana, IL.

    Myotonic dystrophy type 1 (DM1) is one of more than 30 inheritable diseases whose origin can be traced to unstable repeating sequences in genomic DNA. DM1 is caused, in part, by the dysregulation of alternative pre-mRNA splicing that arises from the sequestration of proteins in the muscleblind-like (MBNL) family by expanded, non-coding r(CUG) trinucleotide repeats (TNR). Most therapeutic approaches have focused on developing agents that strongly and selectively bind the toxic r(CUG)exp, thereby inhibiting its sequestration of MBNL proteins. However, this has a number of drawbacks, including the continuous production of progressively longer r(CUG)exp transcripts and, more importantly, it does not stop disease progression and transmission between generations. A more powerful approach is to target the expanded CTG repeats (CTG)n in DNA. Most models propose that TNR expansion occurs in DNA metabolic processes including replication, transcription, and mismatch repair. Longer repeats become more unstable and give rise to unusual secondary structures during these processes such as intra-strand hairpins and loop-outs. We hypothesize small molecules that selectively bind hairpin CTG, loop-out CAG, or CTG•CAG duplex repeats in DNA will allow for an alternative approach to treat DM1 by possibly contracting (CTG)n. Furthermore, these ligands may serve as useful probes for (CTG)n detection. We have found a pyrroloquinazoline small molecule that selectively binds T-T mismatch-containing DNA. Herein, derivatization, binding mode studies, and future work are described.

    THU-G44 TREHALOSE GLYCOPOLYMERS FOR USE IN PROTEIN STABILIZATION

    • Marco Messina ;
    • Jeong Hoon Ko ;
    • Emma Pelegri-O'Day ;
    • Heather Maynard ;

    THU-G44

    TREHALOSE GLYCOPOLYMERS FOR USE IN PROTEIN STABILIZATION

    Marco Messina, Jeong Hoon Ko, Emma Pelegri-O'Day, Heather Maynard.

    University of California, Los Angeles, Los Angeles, CA.

    Proteins play important roles as laboratory reagents and therapeutics for many different diseases. However, proteins are inherently unstable and are prone to degradation by various stressors such as heat, desiccation, and light. Trehalose, a nonreducing disaccharide, has proven to be an effective stabilizer for proteins. Previous work in our lab has demonstrated that trehalose glycopolymers can stabilize proteins against heat and lyophilization better than trehalose as excipients and as protein conjugates. In this study, we synthesized 3 trehalose monomers substituted with styrenyl ether moieties at the C2, C4, and C6 position. Three 8 kDa polymers were synthesized using each monomer separately and one polymer using all of the monomers via free radical polymerization with azobisisobutyronitrile (AIBN) as an initiator. The protein lysozyme was stressed at 90 °C for 20 minutes and β-galactosidase was lyophilized for 3 cycles in the presence of various weight equivalences of each polymer. The glycopolymer containing the C2 regioisomer outperformed the other regioisomers against heat at 25 weight equivalents heat and against lypophilization at 10 weight equivalents. These results suggest that trehalose glycopolymers are promising excipients for the stabilization of proteins against stressors and afforded us valuable insight into the effect polymers decorated with monomers of differing regiochemistry have on the stabilization of proteins. We are currently investigating the ability of these polymers to stabilize monoclonal antibodies and vaccines against heat stress.

    THU-G47 COMPARISON OF DERIVATIZING REAGENTS FOR THE ANALYSIS OF HYPOGLYCIN A IN ACKEE FRUITS (BLIGHIA SAPIDA) BY ULTRA-PERFORMANCE LIQUID CHROMATOGRAPHY

    • Marianita Perez-Gonzalez ;
    • Roberto J. Velez-Pereira ;
    • Ching Chin Lee ;
    • Osvaldo Rosario ;
    • Donna A. Minott-Kates ;
    • Liz Diaz ;

    THU-G47

    COMPARISON OF DERIVATIZING REAGENTS FOR THE ANALYSIS OF HYPOGLYCIN A IN ACKEE FRUITS (BLIGHIA SAPIDA) BY ULTRA-PERFORMANCE LIQUID CHROMATOGRAPHY

    Marianita Perez-Gonzalez1, Roberto J. Velez-Pereira2, Ching Chin Lee3, Osvaldo Rosario1, Donna A. Minott-Kates3, Liz Diaz1.

    1University of Puerto Rico, Rio Piedras Campus, San Juan, PR, 2Waters Technologies, Puerto Rico, Caguas, PR, 3The University of the West Indies, Mona, JM.

    Hypoglycin A (HA) is an amino acid derivative present in the edible portion (arilli) of the Jamaican ackee (Blighia sapida) fruit. HA is a toxic compound found in about 1,000 ppm level concentrations in the unripe fruit. During the maturation process, the concentration of HA in the aril decreases to levels safe for human consumption. Analysis of HA in ripe and processed ackee is normally done by liquid chromatography, but a derivatization step is required to insert a chromophore to the molecule. Phenyl isothiocyanate (PITC) is the most commonly used derivatizing agent. However, this reaction is a multi-step process that is time consuming and generates complicated chromatograms arising from many side reactions. We are applying a faster, simpler, and stable derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatizing agent. AQC derivatization has the advantage of reducing analysis time from hours (with PITC) to approximately 15 minutes. In addition, the side reaction peaks from AQC are considerably less. We are also presenting faster ultra-performance liquid chromatography (UPLC) methods that have yielded good linear responses for both derivatizing agents. The stability of derivatization, limits of detection, and limit of quantization in the absence of the matrix are being presented. Results have shown that AQC-HA is more stable than PITC-derivatized HA. AQC-derivatized HA is stable for 20 days, while PITC-derivatized HA showed variations in response over the first 5 days of analysis. A survey of canned ackee samples and fresh ripe samples show comparable results by both derivatization methods.

    THU-G46 DEVELOPMENT OF A RAPID ASSAY FOR MEASURING GUT PERMEABILITY BY RECOGNITION OF BIOMARKERS VIA A FLUORESCENT PROBE BASED ON BORONIC ACID VIOLOGENS

    • Angel Resendez ;
    • Ruth Zuniga ;
    • Bakthan Singaram ;

    THU-G46

    DEVELOPMENT OF A RAPID ASSAY FOR MEASURING GUT PERMEABILITY BY RECOGNITION OF BIOMARKERS VIA A FLUORESCENT PROBE BASED ON BORONIC ACID VIOLOGENS

    Angel Resendez, Ruth Zuniga, Bakthan Singaram.

    University of California, Santa Cruz, Santa Cruz, CA.

    Gastrointestinal barrier dysfunction is now recognized as an early event in the pathogenesis of several problematic diseases such as inflammatory bowel disease (IBD), Parkinson’s disease, Crohn’s disease, celiac disease, and type 1 and 2 diabetes mellitus. Gastrointestinal permeability can be assessed noninvasively by analyzing saccharide biomarkers in urine such as sucrose, 3-O-methyl-glucose, lactulose, mannitol, and the synthetic sweetener sucralose. Current methods for analyzing these biomarkers require expensive and time-consuming instrumentation such as high performance liquid chromatography/mass spectrometry (LC/MS). An alternative approach has been taken by utilizing a 2-component system that comprises a boronic acid substituted bipyridinium salt that acts dually as the receptor/quencher and a fluorescent reporter dye in which the system operates at physiological pH. A series of boronic acid viologen compounds were synthesized and analyzed against the biomarkers of interest such as mannitol, lactulose, and sucralose. Of the 6 quenchers that were synthesized, the symmetrical 4, 4’-ortho-bipyridinium salt gave the highest fluorescence recovery for each biomarker with a limit of detection and quantification of 0.2 and 0.6 mM for lactulose, 0.1 and 0.3 mM for mannitol, and 0.8 and 2.5 mM for sucralose. This assay has been further validated in clinical studies with human urine samples to demonstrate a proof of principle to measure small intestinal permeability with this 2-component system. This developed 2-component assay demonstrates a useful alternative tool for rapidly measuring changes in gut permeability.

    FRI-G47 DETERMINATION OF VOLATILE AND SEMI-VOLATILE ORGANIC COMPOUNDS OF THE RED MACROALGAE GRACILARIA TIKVAHIAE CULTIVATED UNDER DIFFERENT CONDITIONS USING HEADSPACE-SOLID PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHYñMASS SPECTROMETRY

    • Anibal Hernandez-Vega ;
    • Liz Diaz ;

    FRI-G47

    DETERMINATION OF VOLATILE AND SEMI-VOLATILE ORGANIC COMPOUNDS OF THE RED MACROALGAE GRACILARIA TIKVAHIAE CULTIVATED UNDER DIFFERENT CONDITIONS USING HEADSPACE-SOLID PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHYñMASS SPECTROMETRY

    Anibal Hernandez-Vega, Liz Diaz.

    University of Puerto Rico, Rio Piedras Campus, San Juan, PR.

    The chemical characteristics and the synthesis of secondary metabolites by marine macroalgae depend largely on their surrounding environment. These changes may occur as a mechanism of defense of the algae toward other organisms or to changes in environmental conditions. The effect that physical factors (i.e., salinity, nutrition, and light) have on the production of volatile and semi-volatile organic compounds (VOCs) by the red macroalgae Gracilaria tikvahiae was investigated. If such production can be effectively quantified, it has the potential to serve as an indicator of particular changes in the environment. Headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to characterize the VOCs profile. Our results show that the wild macroalgae produced a large variety of VOCs when compared with those grown under controlled conditions of nutrition, light, and salinity. Aldehydes and sulfides were different between control (wild) and experimental groups. The production of VOCs was greater in algae cultivated with illumination compared to those cultivated with no light. This may indicate that such compounds are a source that comes from both metabolic and photosynthetic processes. Salinity also played an important role in the production of volatile organic compounds. As the percent of salinity increases, the number of VOCs decrease. This may illustrate a possible homeostatic response towards a threatening environment with respect to their stored nutrients, osmoregulation. The difference in the amount and identities of VOCs produced by these algae can be correlated to the environmental conditions in the habitats where they live.

    FRI-G44 RENEWABLE HYDROGEN GENERATION FROM PHOTOCATALYST BY COMPARING GLYCEROL/ETHANOL AS SACRIFICIAL DONOR UNDER VISIBLE LIGHT

    • Tahmina Akter ;
    • Geoffrey Saupe ;

    FRI-G44

    RENEWABLE HYDROGEN GENERATION FROM PHOTOCATALYST BY COMPARING GLYCEROL/ETHANOL AS SACRIFICIAL DONOR UNDER VISIBLE LIGHT

    Tahmina Akter, Geoffrey Saupe.

    The University of Texas at El Paso, El Paso, TX.

    Wide band gap semiconductor photocatalysts, such as titanium dioxide, along with a metal co-catalyst have been used to generate hydrogen fuel from water. However, ultraviolet light is required which limits their utility in solar energy conversion. Modification of these types of semiconductors can sensitize them to visible light, providing a promising way to create clean, renewable hydrogen fuel. Many photocatalysts suffer from poor hydrogen production efficiencies under visible light due to inadequate visible light absorption. In this research, co-precipitating [Ru(bpy)3]2+ sensitizer dye molecules into nanosheet agglomerates provides a new way to modify porous oxide (POX) photocatalysts. At the end, photolysis experiments will be performed using different sacrificial donors with a cocatalyst. The material will be characterized by XRD, TEM, SEM, and EDS.

    FRI-G45 SILICON PHOTONIC MICRORING RESONATORS FOR CHEMICAL AGENT TRANSPORT

    • Alexandria Stanton ;
    • Kali Miller ;
    • Paul Braun ;
    • Ryan Bailey ;

    FRI-G45

    SILICON PHOTONIC MICRORING RESONATORS FOR CHEMICAL AGENT TRANSPORT

    Alexandria Stanton, Kali Miller, Paul Braun, Ryan Bailey.

    University of Illinois at Urbana-Champaign, Urbana, IL.

    Several advances have been made in directing the transport of chemical agents across surfaces, most recently through the use of enthalpic gradients embedded in polymer brushes or hydrogels. However, the interfacing with complementary methods to robustly detect such transported analytes is needed. Not all species of interest have convenient chromophoric or fluorogenic signatures and, in these cases, the detection of universal properties, such as refractive index, provides an attractive analytical alternative. Silicon photonic microring resonators are robust, sensitive, and versatile refractive index detectors that are broadly applicable to a range of analytical challenges. Moreover, these sensors are amenable to a wide range of surface functionalization methods, including the growth of hydrogels and polymer brushes, which could further expand the detection capabilities of this platform to include chemical agents. The combination of microring resonators with recent advances in the creation of precisely controlled gradients within polymeric surfaces might allow for the active and directed transport of concentrated analytes onto specific sensor elements, thereby integrating together the often disparate steps of separation, concentration, and detection to a single sensing device. Current advances in concentrating and detecting standard chemical samples are highly encouraging for future application in concentrating and detecting low-abundant chemical warfare species.

    FRI-G43 TANDEM ELECTROCYCLIZATION-CYCLOADDITIONS OF 6-METHYL-6-VINYLFULVENE

    • Gabriel Cabrera Dorantes ;
    • Ihsan Erden ;

    FRI-G43

    TANDEM ELECTROCYCLIZATION-CYCLOADDITIONS OF 6-METHYL-6-VINYLFULVENE

    Gabriel Cabrera Dorantes, Ihsan Erden.

    San Francisco State, San Francisco, CA.

    The 6-Vinylfulvenes are versatile and reactive substrates, yet their chemistry has remained mostly unexplored due to the paucity of general and high-yielding methods for their syntheses. Recently, we developed a general synthesis of a large number of 6-vinylfulvenes and decided to systematically explore their chemistry. The first in this series was the oxidative transformations of 6-methyl-6-vinylfulvene. We now report on the cycloadditions of dihydropentalenes, derived from the thermal 8-electrocyclization of 6-methyl-6-vinylfulvene, with tropone and tetracyclone, respectively. Spectroscopic characterization of the cycloadducts, as well as frontier orbital considerations governing the observed periselectivities will be presented.

    FRI-G48 TOWARD THE ENANTIOSELECTIVE TOTAL SYNTHESIS OF ALOPECURONE C

    • Noah Burlow ;
    • Kellan Lamb ;
    • Jared Shaw ;

    FRI-G48

    TOWARD THE ENANTIOSELECTIVE TOTAL SYNTHESIS OF ALOPECURONE C

    Noah Burlow, Kellan Lamb, Jared Shaw.

    University of California, Davis, Davis, CA.

    Progress toward the first total synthesis of alopecurone C, a resveratrol-derived flavanostilbene natural product, is described. Our interest in this molecule stems from its reported antibiotic activity which includes the inhibition of greater than 20 strains of methicillin-resistant Staphylococcus aureus (MRSA). To date, we have assembled the dihydrobenzofuran core using Rh-catalyzed asymmetric C-H insertion methodology previously developed in our lab. This single transformation established 2 of the 3 stereogenic centers present in the molecule. Current synthetic efforts are focused on the flavanone fragment, which we aim to construct by organocatalytic cyclization of an ortho-hydroxychalcone intermediate.

    THU-G42 ACCURATE MOLECULAR MECHANICS FOR GAS LIGANDED HEME

    • David Poole III ;
    • Raymond Esquerra ;

    THU-G42

    ACCURATE MOLECULAR MECHANICS FOR GAS LIGANDED HEME

    David Poole III, Raymond Esquerra.

    San Francisco State University, San Francisco, CA.

    Heme-containing globular proteins are essential for storage, transport, and sensing of small molecule gases in biological systems. Myoglobin and hemoglobin in particular have been extensively studied by a variety of techniques, including molecular mechanics simulations. However, models for heme are not inclusive of ring distortions and specific modelling of effects critical to mechanisms of ligand coordination. As a result, the specific dynamical structure-function relationships involved in gas binding by these proteins are not predicted by present molecular mechanics methods. In this work we present improved force field parameters which address these deficiencies with optimized ab initio quantum mechanics simulations of ligated ferrous heme groups. We validate these new parameters using molecular dynamics free energy perturbation to compare the predicted binding affinities of myoglobin mutants for gaseous ligands to experimental values obtained from nanosecond time-resolved optical spectroscopy.

    THU-G43 SYNTHESIS AND ASSESSMENT OF CO RELEASE CAPACITY OF MANGANESE CARBONYL COMPLEXES DERIVED FROM RIGID ALPHA-LIGANDS OF VARIED COMPLEXITY

    • Jorge Jimenez ;
    • Indranil Chakraborty ;
    • Pradip Mascharak ;

    THU-G43

    SYNTHESIS AND ASSESSMENT OF CO RELEASE CAPACITY OF MANGANESE CARBONYL COMPLEXES DERIVED FROM RIGID ALPHA-LIGANDS OF VARIED COMPLEXITY

    Jorge Jimenez, Indranil Chakraborty, Pradip Mascharak.

    University of California, Santa Cruz, Santa Cruz, CA.

    Carbon monoxide, which usually bears a negative connotation as a “silent killer”, has recently been shown to impart several salutary effects in mammalian physiology at low concentrations. Moreover, it has also been realized that, at relatively high concentrations, CO exhibits pro-apoptotic effects on hyperproliferative cells, like aggressive T-cells and malignant cells. The limitations of administration of CO in gaseous form in a controllable fashion inspired the need for CO releasing molecules (CO-RM), which are suitably designed metal carbonyl complexes that can release CO with any internal or external trigger. Furthermore, photo-induced CO-releasing molecules (photo-CORMs) have emerged as credible alternatives where the CO release can be triggered only upon illumination. Four manganese carbonyl complexes of the type [MnBr(CO)3(N^N = α-diimine ligands), namely [MnBr(CO)3(phen)], [MnBr(CO)3(dafo), and Mn[Br(CO)3(pyzphen) (where bpy = bipyridine, phen = 1,10-phenanthroline, dafo = 4,5-diazafluoren-9-one and pyzphen = pyrazine[2,3-f][1,10]-phenanthroline) have been synthesized and structurally characterized. These 4 complexes containing the fac-[Mn(CO)3] motif release CO upon illumination with low power visible and UV light. The CO release rates and the absorption maxima of the complexes are, however, very similar despite systematic increase in structural complexity in the rigid α-diimine ligand frames. This is quite in contrary to manganese carbonyl complexes derived from α-diimine ligands in which at least one of the imine functions is not part of the rigid ring systems. Results of this study will provide help in the future design of ligand frames suitable for the synthesis of photoCORMs to deliver CO to biological targets under the control of light.

    THU-G48 MACROMOLECULAR DESIGNS FOR NON-AQUEOUS REDOX FLOW BATTERY SYSTEMS

    • Elena C. Montoto ;
    • Gavvalapalli Nagarjuna ;
    • Nina Sekerak ;
    • Marissa Kneer ;
    • Kenneth Hernandez-Burgos ;
    • Jeffrey S. Moore ;
    • Joaquin Rodriguez-Lopez ;

    THU-G48

    MACROMOLECULAR DESIGNS FOR NON-AQUEOUS REDOX FLOW BATTERY SYSTEMS

    Elena C. Montoto1, Gavvalapalli Nagarjuna1, Nina Sekerak1, Marissa Kneer2, Kenneth Hernandez-Burgos1, Jeffrey S. Moore1, Joaquin Rodriguez-Lopez1.

    1University of Illinois at Urbana-Champaign, Urbana, IL, 2Taylor University, Upland, IN.

    Redox flow batteries (RFBs) have been shown to offer efficient grid-scale energy storage applications due to their performance and easy scalability. Aqueous RFBs are currently limited by the potential window of water, thus non-aqueous counterparts that can use a wider range of redox active species offer several advantages such as higher power and energy densities. Nevertheless, currently used ion-exchange membranes (IEMs) show low ionic conductivity in organic media. By utilizing size-exclusion principles in designing redox active species, poorly performing IEMs can be substituted with inexpensive porous separators that show higher ionic conductivities. For this approach, we have studied organic redox active colloids (RACs) in the submicron range to prevent crossover through nanoporous separators. A key challenge is controlling the size of RACs without adversely affecting chemical and structural stability, solubility, and rheological properties. This work will demonstrate the progress made toward identifying an all-RAC NRFB system by electrochemical methods. Both catholyte and anolyte RAC materials will be shown along with their characterization and performance. Our goal is to show that the use of RACs and porous separators are a viable method for designing NRFB systems.