“ … Yukilevich, Joanne D. Kehlbeck (1) Department of Chemistry, Union … Department of Biology, Union … T. Harvey, S. Nguyen, J. Kehlbeck, A. Park. “The search for casual traits of … ”
Abstract
Drosophila athabasca, a species complex native to North America, provides a unique opportunity to study nascent speciation arising from sexual isolation. Some have suggested that cuticular hydrocarbons (CHCs) influence the sexual selection process. Extensive analyses have resulted in complex understandings of CHC involvement in insect mate preference, with minimal work focusing on D. athabasca. The goal of this study is to identify, synthesize and measure biologically relevant quantities of CHCs present in this species complex. Gas chromatography – mass spectrometry (GC-MS) from several isofemale lines of D. athabasca allows for characterization of contributing compounds including saturated, unsaturated, and branched alkanes, fatty acids, acetates, and esters. Identification of these compounds using characteristic fragmentation patterns allowed for confirmation by synthetic standards. To date, over 100 CHCs have been characterized in D. athabasca using these analytical and organic methods. An overview of the analysis techniques and future direction will be presented.
“ … , Joanne D. Kehlbeck Department of Chemistry, Union College, … 2012, 109(19), 7469–7474. Acknowledgements • Professor Joanne Kehlbeck • Professor Kristin … Kehlbeck Lab is … ”
Abstract
Metacaspase are proteases that are involved in the cell death pathway of fungi. A better understanding of metacaspase might be helpful in the development of the antifungal drugs. The project was a collaboration between the Fox Lab and the Kehlbeck Lab. The Fox Lab aims to elucidate the structures and the properties of five types of metacaspase enzyme in S. commune fungus. The Kehlbeck Lab, has been working on synthesizing different inhibitors for the S. commune metacaspase. Z-Arg(Pmc)-benzothiazole served has been shown to inhibit similar metacaspases in similar organisms. The project aimed to propose the most effective synthetic pathway to generate Z-Arg(Pmc)-benzothiazole that would ideally allow us to explore other related inhibitors. This project focused on studying the direct one-way synthesis pathway from a carboxylic acid and heteroaryl halides. Several model reactions with different R-groups were tested and analyzed by NMR and GC-MS to study the effectiveness of the synthesis pathway. The model reaction using Z-Ala-OH gave the most promising NMR data. The NMR result suggested that a new compound, which was different from the starting materials, had been synthesized. In the near future, the synthesis method will be studied using different model reactions to compare how it works on structures with different R-groups. The final goal of the research is to make a library of different inhibitors for S.commune metacaspase.
“ … Gabriola Island, B.C.: New Society, 2004. Print. 7. Kehlbeck,Joanne D., Michael E. Hagerman, Brian D. Cohen … ”
Abstract
The Department of Mechanical Engineering at Union College in conjunction with the Department of Chemistry and Biological Sciences are presently involved in the research and development of thin film solar nanocomposites. The thin film solar nanocomposite solar devices offer a cheaper alternative to solar technology, however the efficiencies of these thin film solar devices are very low compared to their silicon-based counterparts. The group’s ultimate goal is to produce a flexible solar cell with efficiencies that are comparable to traditional silicon-based solar cells. The collaboration of the Department of Mechanical Engineering at Union College has provided new insights that could help increase the development of solar nanocomposites. While there has been significant research on fabrication techniques, this project proposes to investigate the mechanical properties of the solar cell design, specifically the PEDOT:PSS/PET:ITO interface, to determine a correlation between interfacial interactions and overall efficiency.
“ … as well as a course on “Culinary Chemistry” with professor Joanne Kehlbeck … Scholars with co-investigators Joanne … Michael Vineyard (physics) and Seyfollah Maleki (physics). JoanneKehlbeck, … ”
Acrylamide, a neurotoxin that forms as a by-product of the Maillard reaction, was recently identified in several foodstuffs that are roasted or browned, such as potatoes, bread and roasted coffee beans. Formation of acrylamide in roasted coffee beans contributes to the overall human exposure to this toxin, resulting in legislation requiring labels to warn the public of the risks of consumption of brewed coffee. In this study, a method has been developed for the analysis of acrylamide in brewed coffee, and factors contributing to acrylamide levels have been investigated. The current method was adapted from a published protocol and modified to reduce variability. Briefly, trace level analysis of acrylamide in coffee was conducted using simplified liquid extraction followed by liquid chromatography-tandem mass spectrometry. The method provided good linearity of response (R2 > 0.998) and suitable limits of quantification (0.022 µg/kg) and detection (0.0067 µg/kg). Extraction efficiencies ranged from 85-120%. This optimized method was used to investigate confounding influences that affect acrylamide concentrations, such as the source of the coffee beans and the brew method. Factors studied include the mass of grounds used to brew coffee, the roast type, and the effects of decaffeination. Ongoing studies are focused on the analysis of single origin coffee bean samples to investigate the effects of soil conditions and local climates on acrylamide formation, as well as to determine other factors that may impact acrylamide levels in brewed coffee. Acrylamide, a neurotoxin that forms as a by-product of the Maillard reaction, was recently identified in several foodstuffs that are roasted or browned, such as potatoes, bread and roasted coffee beans. Formation of acrylamide in roasted coffee beans contributes to the overall human exposure to this toxin, resulting in legislation requiring labels to warn the public of the risks of consumption of brewed coffee. In this study, a method has been developed for the analysis of acrylamide in brewed coffee, and factors contributing to acrylamide levels have been investigated. The current method was adapted from a published protocol and modified to reduce variability. Briefly, trace level analysis of acrylamide in coffee was conducted using simplified liquid extraction followed by liquid chromatography-tandem mass spectrometry. The method provided good linearity of response (R2 > 0.998) and suitable limits of quantification (0.022 µg/kg) and detection (0.0067 µg/kg). Extraction efficiencies ranged from 85-120%. This optimized method was used to investigate confounding influences that affect acrylamide concentrations, such as the source of the coffee beans and the brew method. Factors studied include the mass of grounds used to brew coffee, the roast type, and the effects of decaffeination. Ongoing studies are focused on the analysis of single origin coffee bean samples to investigate the effects of soil conditions and local climates on acrylamide formation, as well as to determine other factors that may impact acrylamide levels in brewed coffee.
Amino acids, like asparagine, react with sugars via the Maillard reaction to form compounds that contribute to the color and flavor of roasted foods. However, some undesired products also form during this reaction, one of them being acrylamide. Acrylamide is a neurotoxin and a potential endocrine-disrupting chemical (EDC), and increased dietary amounts of acrylamide have been linked to different types of cancers, including ovary, renal and endometrial. EDCs can impair the endocrine system in a variety of ways including mimicking hormonal activity, interfering with metabolism, excretion and release. As a neurotoxin, acrylamide can affect memory, cognitive function and learning. In this study, acrylamide is extracted from the brewed coffee using simplified liquid extraction and analyzed alongside known standards using liquid chromatography-tandem mass spectrometry. The accuracy of the method has been validated using a standard reference material. This method has been used to quantify acrylamide concentrations in various types of brewed coffee and investigate the effects of variables such as type of roast, decaffeination, and bean origin. Our results suggest that differences in roast or caffeination do not significantly affect acrylamide concentrations in brewed coffee. Ongoing studies include improving precision and accuracy using the established method and applying the method to investigate trends of acrylamide formation in various types of brewed coffee.
“ … Acknowledgments ● Joanne D. Kehlbeck and Laura A. MacManus-Spencer ● LAMS Lab … ”
Abstract
The color and flavor of roasted foods arises from molecules that are formed when amino acids, like asparagine, react with sugars via the Maillard reaction. However, some undesired products also form during this reaction, one of them being acrylamide. Acrylamide has been detected in tobacco smoke, tea, coffee and water. Acrylamide was not detected in green coffee beans; therefore, roasting is required to form this chemical. The frequency with which the public is exposed to acrylamide and the magnitude of that exposure is a public health concern because acrylamide is known to have a variety of toxic effects. Acrylamide is a neurotoxin and a potential endocrine-disrupting chemical (EDC), and increased dietary amounts of acrylamide have been linked to different types of cancer, including ovary, renal and endometrial. EDCs can impair the endocrine system in a variety of ways including mimicking hormonal activity, interfering with metabolism, excretion and release. As a neurotoxin, acrylamide can affect memory, cognitive function and learning. The younger population is the most susceptible to the effects of EDCs, and foods containing acrylamide are popular and consumed in large amounts within that population, such as chicken nuggets, french fries, cereal, and cookies. In this study, acrylamide is extracted from brewed coffee using simplified liquid extraction and analyzed using liquid chromatography-tandem mass spectrometry. The accuracy of the method has been validated using a standard reference material of fortified instant coffee. This method has been used to quantify acrylamide concentrations in various types of brewed coffee and to investigate the effects of variables such as type of roast, decaffeination, and bean origin. Our results suggest that differences in roast or caffeination do not significantly affect acrylamide concentrations in brewed coffee. Ongoing studies include further improving method precision and continuing to investigate trends in acrylamide formation in various types of brewed coffee.
“ … I would also like to acknowledge Professor Joanne Kehlbeck for invaluable conversations and … … ”
Abstract
Polyaniline (PANI) is a highly conductive polymer that offers promise for use in sensors, light emitting diodes and solar cells. In order to achieve widespread commercial success, polyaniline needs to be water processable. Relying upon PANI’s natural ability to adhere to reaction vessels, we have produced polyaniline via in situ film formation. We believe that control over film formation is crucial to achieving a water-processable, environmentally friendly route to PANI?based devices. To this end we have employed Laponite nanoparticles, vanadium oxide, and varied morphosynthetic conditions to exert control over the growth of polyaniline and tune the dimensionality and nanomorphology of polyaniline nanomaterials. We have studied the resulting nanomaterials via atomic force microscopy, scanning electron microscopy, and UV/Vis spectroscopy. Our results indicate the successful syntheses of conductive polyaniline nanoparticles that exhibit electronic and morphological differences that stem from variations in the synthetic pathways.
“ … 25 Acknowledgements Professor Barbara Danowski Professor Joanne Kehlbeck Merck Fellowship for Interdisciplinary … ”
Abstract
Cell Penetrating Peptides (CPPs) are short amino acid sequences that are able to traverse
the cell membrane and bring with them attached cargo. Because the membrane acts as a
protective barrier, CPPs are potential tools for drug delivery. The Kehlbeck lab began synthesis of a novel CPP, while we, in the Danowski lab designed cellular uptake assays in order to compare them to known CPPs. The ideal assay will allow us to compare uptake efficiency and follow the cargo, from endocytic uptake, to release in the cytoplasm. In this study I used rhodamine to determine optimal fluorophore (cargo) concentration for visualization in cells. Results with unconjugated rhodamine showed that optimal conditions are overnight incubation at a concentration of 0.02 uM. We then did a pilot study with Snap-Tag (New England BioLabs) as a first step in reaching a more biological assay. Cells were transfected with a plasmid encoding the Cytochrome c oxidase enzyme. The transfected cells were given a fluorescent substrate molecule that becomes covalently attached to Cytochrome c oxidase and trapped in the cytoplasm. We will modify this assay, by attaching a membrane-impermeant fluorescent substrate molecule to our CPPs. This approach is promising but requires further work to achieve higher transfection rates.
“ … /WATERMAN DESIGN 2. … , 2012, 6 (2), 1715-1723. 32. Joanne D. Kehlbeck, Michael E. Hagerman, Brian D. Cohen, Jennifer … ”
Abstract
We have successfully created the first example of a bicontinuous conductive polymer network for use in hybrid QD-polymer solar cells via a mechanochemical route. Heterometallic dicyanoaurate coordination polymers were used as intercalative hosts to promote in situ growth of emeraldine polyaniline (PANI), which provides electron conduction pathways within the active layer. Cu2+-excanged Laponite RD nanodiscs were used to direct the self-assembly of the bicontinuous polymer networks and nanomorphology within the nanocomposites. These PANI/Laponite coordination polymers were extensively characterized by scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectroscopy in order to probe polymer-nanoparticle and polymer-polymer interactions. PANI and Laponite both serve to template the coordination polymer composites. Nano- and microstructures ranging from flowers to hollow spheres to wires-upon-wires growth were observed. Several bulk heterojunction solar cell active layers were synthesized by mixing varying ratios of the PANI/Laponite coordination polymer with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), a hole-conductive polymer, and tris(bipyridine)ruthenium(II) chloride (Rubipy), a chromophore. These active layers were used to fabricate bulk heterojunction solar cells. Future work will include making conductivity measurements on these solar cells, as well as fabricating new solar cells with incorporated CdSe quantum dots. The ability to tune Au-Au aurophilic and Au-Se interactions may enhance the monodispersion of semiconductor nanoparticle chromophores, leading to improved photoconductivity.
“ … like to thank Professors Matthew Manon, James Adrian, and Joanne Kehlbeck for helping me with the … suspensions. … imaging sensors. Acc. Chem. Res. 1998, 31, 267-278. 36. Kehlbeck, … ”
Abstract
Ceria has received great attention for the removal of water contaminants due to its high oxygen storage capacity, marked oxygen ion conductivity, and tunable catalytic activity. Zhong et al. suggested that ceria (cerium oxide) microspheres with nanoscale 3D flowerlike morphology represent a promising inorganic synthetic material to remove water contaminants such as As(V) and Cr(VI) from drinking water. The 3D flowerlike micro/nanocomposite ceria offer key advantages over other nanoparticle based remediation systems as they can be easily removed via conventional microfiltration. The goals of this thesis project were to test the reproducibility of the synthesis of the 3D flowerlike ceria, and to assess the ability of the material to remove As(V) and Cr(VI) from water. Analyses using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and attenuated total reflectance-infrared spectroscopy (ATR-IR) confirmed the successful synthesis of the 3D flowerlike ceria. Inductively coupled plasma - mass spectrometry (ICP-MS) was used to quantify the removal of As(V) and Cr(VI) from water; results revealed that the concentrations of As(V) and Cr(VI) were reduced by more than 90% using the 3D flowerlike ceria, and their final concentrations were lower than the maximum contaminant levels set by the U.S. EPA. SEM images of both exposed and recycled 3D flowerlike ceria indicated that the 3D flowerlike morphology was retained after exposure to As(V) and Cr(VI) and after washing with NaOH solution. The 3D flowerlike ceria is an effective nanosorbent for the removal of As(V) and Cr(VI) in water treatment.
“ … College, Department of Chemistry, June 2017. ADVISOR: Joanne D. KEHLBECK Cuticular hydrocarbons (CHCs) have been … 2012, 7 (7). (26) Yukilevich, R.; Harvey, T.; Nguyen, S.; Kehlbeck, J.; Park … ”
Abstract
Cuticular hydrocarbons (CHCs) have been studied extensively and their roles explored for various species of insects. However, only a single reported study has focused on the role of CHCs in Drosophila athabasca, a species of fruit fly native to North America. The work herein describes advances in identification, synthesis and quantification of biologically relevant CHCs present in this species. Identifying CHC profile differences among D. athabasca sub-races (Eastern A, Eastern B and WestNorthern) was performed using multiple analytical techniques. Synthesis of proposed structures confirmed their identity. External standard curves were used to quantify CHCs. GC-MS analysis of CHCs from several isofemale lines of D. Athabasca reveals multiple monoenes, dienes, and branched alkanes. Positions of unsaturation within CHCs were determined using dimethyl disulfide (DMDS) derivatization and branching locations were determined via bromination and subsequent elimination. Synthesis of mono- and di- unsaturated CHCs was accomplished through alkyl substitution, followed by cis-selective reduction. Branched alkanes were generated in a similar fashion or through coupled Grignard-elimination-reduction schemes. External standard curves, generated from synthesized compounds, can be used to produce synthetic profiles for continued exploration of CHC role within the D. athabasca system.
