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«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»

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Continuing loss of islet β-cell mass in the pancreas is universal in all types of diabetes. Recent studies have shown that a 15 amino acid peptide segment of the islet-neogenesis associated protein (INGAP) is capable of inducing the formation of new islets in the pancreas. Administration of the INGAP peptide (INGAP-P) to nondiabetic and diabetic animal models is associated with increased β-cell mass, reversal of hyperglycemia, and differentiation of duct cells into neoendocrine cells. The mechanism of islet neogenesis via INGAP and INGAP-P has not been well characterized. Our work aims to study the roles of kinases in INGAP-initiated signal transduction that leads to β-cell proliferation. Activation of kinases such as ERK1/2, Akt, PKA, PKC, and CAMKII will be investigated to reveal clues as to the primary signaling events following the interaction between INGAP-P and its receptor(s) on the β-cell surface. Currently, we focus on the organic synthesis of INGAP-P as well as the materials for solid-format kinase assays. Peptides used in this work were synthesized by solid phase peptide synthesis using FMOC chemistry. These synthesized peptides were then purified by HPLC, and their identities were characterized by mass spectroscopy. The next stage of the project includes MTS proliferation assay of islet cells treated with INGAP-P and controls and kinase assays using cell lysates. The temporal order of kinase activation will be investigated to disclose the composition of signal transduction in INGAP-P mediated islet cell proliferation.

SAT-19

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FRI-25

NEW FABRICATION OF THICK FILM IN TACKLING SENSING UNDER EXTREME CONDITION

Pablo Rivera, Mian Jiang.

University of Houston-Downtown, Houston, TX.

A novel, thick nickel hydroxide Ni(OH)2 film for the analytical determination of different compounds was prepared.

The film formation involves a 2-step process: the fabrication of nickel hexacyanoferrate (NiHCF) and the subsequent conversion of NiHCF into nickel hydroxide film. The first step was realized by immersing the glassy carbon (GC) electrode into a solution mixture of supporting electrolyte, nickel(II) salt, and potassium hexacyanoferrate, with a voltammetric scanning between 0.0V and approximately +0.6 V for 3 or more cycles. The resultant NiHCF film/GC was rinsed and then placed into 0.1 M NaOH with voltammetric scanning in the same potential window as above. The finalized deposits on the GC surface were visible, dense, and homogeneous. Comparing with the literature-published Ni(OH)2 film made by others and our own approaches reported earlier, this current proposed method resulted in a thicker film deposit. This study also possesses the uniqueness of using a surface film conversion approach, which

243 UNDERGRADUATE POSTER ABSTRACTS

has broadened the existing film-making arena. The modified electrode has been found to have several applications including electrocatalysis of amino acids and carbohydrates. [This work was supported by NASA-TSGC-NIP, SACPUARP, Starter-award of UARP, and Welch Grant ( BJ-0027.)] FRI-13

ISOLATION OF FLAVONOIDS IN ALFALFA EXTRACT AND THE FORMATION OF GOLD NANOPARTICLES

Amanda Villalobos, Milka Montes.

The University of Texas of the Permian Basin, Odessa, TX.

Nanoparticles are used throughout scientific fields of study, ranging from nanotechnology to medicine. The reduction of gold ions to produce nanoparticles in live plants has been used for quite some time. Scientists are able to produce not only gold and silver, but other transition metal nanoparticles to be used in industry without harmful effects to the environment. One way to produce these nanoparticles and reduce the gold ion would be to find and isolate the reducing agent within a live plant. In order to isolate the reducing compound, an alfalfa biomass was set to reflux and an alfalfa extract was created by vacuum filtration. After the filtration, the extract was separated using a flash chromatography system and 1:1.5 ratio of ethyl acetate and methanol solvent, respectively. After the completed separation, the fractions were dried using a vacuum pump system. The fractions were then analyzed by UV-Vis spectroscopy, gas chromatography, and nuclear magnetic resonance spectroscopy. Many compounds were detected, but one particular compound was isolated. The suspected compound is a flavonoid with a mass of 393 grams per mole. Once the reducing compound is identified, the compound should be oxidized by gold ions and bring the gold ions to a lower valence.

FRI-11

CHARACTERIZATION OF A PROTEIN PHOTORECEPTOR IN ITS LIGHT-ADAPTED STATE USING ATOMIC

FORCE MICROSCOPY

Blaire Sorenson, Daniel Westcott, Kenneth Nicholson, Brian Lampert, Justin Thomas, Alexandra Sakols, Sarah Vorphal, Emina Stojkovic, Stefan Tsonchev.

Northeastern Illinois University, Chicago, IL.

Bacteriophytochromes (BphPs) are red-light photoreceptors found in photosynthetic and nonphotosynthetic bacteria that have been recently engineered as infrared fluorescent tissue markers. Light-induced, global structural changes are proposed to originate within their covalently linked biliverdin chromophore and propagate through the protein.

These changes are believed to be reversible during the protein’s photoconversion between two spectrally distinct light absorbing states. RpBphP3 (P3), from Rhodopseudomonas palustris, undergoes reversible photoconversion between red (Pr) and unique near-red (Pnr) light-absorbing states and is naturally fluorescent, unlike classical BphPs that undergo reversible Pr/Pfr photoconversion. Due to size and photosensitivity of BphPs, structures of the intact proteins have not been resolved by NMR and/or X-ray crystallography. We have used fluid cell atomic force microscopy (AFM) to investigate the structure of intact P3 in its light-adapted state. Unlike other characterization techniques, AFM allows individual dimers to be imaged under biologically relevant conditions with individual domain resolution. Currently, we are using the Gwyddion software to analyze and compare measurements of single dimers on mica. Averaging the images of multiple dimers has been found to improve domain resolution and to help further complete dimensional analysis of P3. Future work includes imaging the truncated version of P3 and directly comparing the structure with the full length P3. Also, we will image the dark adapted state of the protein. The goal is to gain insight into the mechanism of the unique P3 photoconversion and fluorescence, which may be used to design a novel, biologically inert infrared fluorescent tissue marker.





FRI-15

THE EFFECTS OF STEREOCHEMISTRY AND N-METHYLATION ON PERMEABILITY AND BIOAVAILABILITY OF

SYNTHESIZED CYCLIC HEXAPEPTIDE PRODUCTS

Alexandra Ponkey, William Hewitt, Scott Lokey.

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

Cyclic peptides are at the forefront of efforts to pursue “undruggable” therapeutic targets. The targets of conventional small-molecule synthetic drugs are generally limited to enzyme-active sites and receptors, whereas cyclic peptides, which are both larger and more complex, have the potential to interact with more challenging biological targets such as allosteric binding sites and protein-to-protein interactions. The permeability and bioactivity exhibited by these compounds provides potential access to a relatively untapped realm of drug discovery. Our overall goals

244 UNDERGRADUATE POSTER ABSTRACTS

are to find permeable cyclic peptide scaffolds by varying both stereochemistry and N-methylation, and to broaden our understanding of the true potential of these cyclic peptide molecules. Split-pool hexapeptide libraries were synthesized using solid phase peptide synthesis (SPPS) and will be tested for passive permeability through parallel artificial membrane permeability assay (PAMPA). The hope is to identify hits in PAMPA and to further explore these compounds. Identified hits will be determined through recursive deconvolution followed by resynthesis to run more specified tests of permeability and bioavailability.

SAT-7

SYNTHESIS OF ALKYLTHIO BENZENE DERIVATIVES VIA SIMULTANEOUS DIAZOTIZATION AND

NUCLEOPHILIC DISPLACEMENT

Juan Deleija-Lujano Jr., Dr. Jose Gutierrez.

University of Texas-Pan American, Edinburg, TX.

P-phenylene vinylenes (PPV) are conducting polymers incorporated into LEDs and play a role in the optical properties of the polymer itself. Hence, for the introduction of these functional groups, various synthetic routes have been proposed. Arene diazonium salts have widespread applications in organic synthesis because they contain an excellent leaving group that can be replaced by a nucleophile. Reported here is the synthesis of alkylthiobenzene derivatives by simultaneous diazotization of aromatic amines and nucleophilic displacement. The method is fairly general and results in moderate yields for aromatic amines containing strong electron withdrawing or electron releasing groups. Product yields were comparable regardless of the steric hindrance of the thiol or functional groups.

This procedure also allows for the incorporation of tertiary alkyl-thio groups, a problem often faced by other synthetic routes involving metal catalyst or gas-phase conditions. The products were characterized by 1H-NMR and 13C-NMR.

SAT-20

SYNTHESIS AND CHARACTERIZATION OF THE THERMOTROPIC PROPERTIES OF POLYMERIZABLE

CATANIONIC SURFACTANTS

Bonnie Flowers, Robin Jose.

University of Houston-Downtown, Houston, TX.

Two novel polymerizable catanionic surfactants were prepared from (12-Acryloyloxydodecyl)trimethylammonium bromide with sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium dodecyl benzene sulfonate (DBS),

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SAT-25

CARBON DOTS REDUCE FIBRILLATION OF INSULIN AND AMYLOID BETA

Clayton Wandishin, Roger Leblanc, Sheba Johnson.

University of Miami, Coral Gables, FL.

Carbon dots are tiny carbon nanostructures, up to 10 nm in diameter, with a wide range of potential uses. Because of their structure and size, carbon dots can easily pass through the blood brain barrier and other membranes within the human body. This, in addition to their nontoxicity, makes them a valuable prospect for biomedical applications. Our carbon dots are prepared by heating a mixture of polyethylene glycol and glycerol to above 320 °C, adding citric acid, and maintaining the reaction for 4 hours. These are then characterized through fluorescence spectroscopy, ultraviolet spectroscopy, and atomic-force microscopy. The resulting carbon dots are hydrophilic in nature and readily soluble in a water-based solution containing insulin or beta amyloid. The proteins are then incubated with carbon dots at 37 °C (body temperature) in a phosphate-buffered solution with a pH of 7.4. This is done in order to mimic body conditions where fibrillation occurs naturally. The carbon dot/protein mixtures are then analyzed using atomic-force microscopy and circular dichromism to evaluate the presence and extent of fibrillation. Previous research has shown specifically that quantum dots, a structurally similar but biologically toxic relative of carbon dots, can aid in the reduction of protein fibrillation. Our goal is to show that carbon dots can yield similar results, allowing for further research with carbon dots and possible treatment methods for diseases such as Alzheimer’s dementia and Parkinson’s disease.

245 UNDERGRADUATE POSTER ABSTRACTS

FRI-4

SILVER NANOPARTICLES SUPPORTED BY RICE HUSK SILICA: SYNTHESIS, CHARACTERIZATION, AND

CATALYTIC APPLICATION

Davontae Habbit, Luyi Sun.

Texas State University-San Marcos, San Marcos, TX.

Herein, a facile method has been developed for the synthesis of silver nanoparticles (Ag NPs) supported by the silica obtained from rice husks (RHs). In this research, (3-aminopropyl)triethoxysilane (APTES) was used to modify RH silica, while silver nitrate and sodium borohydride (NaBH4) were used as Ag precursor and reducing agent, respectively. It was found that the amino groups of the modified silica could help attach Ag precursors to the surface of the silica and also stabilize the synthesized Ag NPs. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy were used to characterize the products. The results showed that Ag NPs with a diameter of ca. 10-15 nm were well dispersed on the surface of RH silica. Catalytic experiments showed that the silica-supported Ag NPs exhibited high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH4.

SAT-14

EXPLAINING THE MECHANISM OF DOMAIN FORMATION USING MOLECULAR DYNAMICS SIMULATIONS OF

COARSE-GRAINED DIPALMITOYLPHOPHATIDYLCHOLINE LIPID BILAYERS CONTAINING CHOLESTEROL

Alfredo Perez1, Lutz Maibaum2.

University of California, San Diego, La Jolla, CA, 2University of Washington, Seattle, WA.

1 It has been observed that domains form in ternary systems involving a high melting point lipid, low melting point lipid, and cholesterol. It is speculated that these lipid rafts play a key role in cellular signaling, trafficking, and structure.

Domains vary in size and composition, which may allow for the initiation of specific signaling cascades. Although the formation of different phases in lipid bilayers has been directly observed by other groups, the mechanism is unknown. Experiments have shown that spatial heterogeneities do not form in the absence of cholesterol, hinting that cholesterol’s higher solubility in saturated lipids relative to unsaturated lipids may play key roles in the mechanism.



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