Oral Presentations Saturday, April 12 Buller 207 Program and - - PDF document

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Oral Presentations Saturday, April 12 Buller 207 Program and Abstracts

Program

9:00 Reception, coffee Buller 207 9:20 Ashley Gordon

• Dr. Gregg Tomy

Determination of the Compatibility of Current Forensic Collections & Analysis with GC‐MS Techniques for Latent Fingerprints 9:40 David Smith

• Dr. David Herbert

New Catalyst Designs for the Electrochemical Reduction

• f CO2

10:00 Swai Mon Khaing

• Dr. James Nagy
• Dr. Hélène Perreault

Identification of proteins associated with Connexin36 using mass spectrometry 10:20 James Lloyd

• Dr. Mario Bieringer

Synthesis and Structural Characterization

• f Ca(1‐x)SrxIn2O4 (0 ≤ x ≤ 1)

10:40 Break 11:00 Ewan McRae

• Dr. Sean McKenna

Recombinant Expression of the RHAU Helicase protein in E. coli 11:20 Sterling Desmond

• Dr. Jennifer van Wijngaarden

Rotational Levels within the Vibrational Spectra

• f Thietane and Oxetane

11:40 Katherine Cordova

• Dr. Hélène Perreault

Development of immunoglobulin G modified silica beads as a novel stationary phase for glycopeptide enrichment 12:00 Patrick Giesbrecht

• Dr. Michael Freund

Formation of a Conducting Polymer‐WO3 Bulk Heterojunction for Resistive Memory 12:20 Pizza Lunch Parker 256 1:20 Rebecca Sherbo

• Dr. Peter Budzelaar

Synthesis and Characterization of Rhodium β‐diiminate Complexes 1:40 Benchmen Choun Trieu

• Dr. Frank Schweizer

Synthesis of Antimicrobial Peptides Containing Pro‐Arg‐Pro Repeating Motifs 2:00 Heather Cavers

• Dr. Michael Freund

Functionalization and Characterization of Representative Model Crystal Surfaces on Silicon Microwires 2:20 Roy Hutchings

• Dr. Jörg Stetefeld

Purification and crystal screening of the cytoplasmic tail segment of a K+/H+ antiporter from Vibrio cholerae 2:40 Break 3:00 Shaun MacLean

• Dr. H. Georg Schreckenbach

Computational Study of a Binuclear Pentavalent Uranyl Complex in a Schiff‐Base Polypyrrolic Macrocycle 3:20 Alexandra C. Ciapala

• Dr. Kathleen M. Gough

FTIR spectrochemical analysis of nutritional composition of the diatom Fragilaria cylindrus after exposure to varying light levels 3:40 Hayden Glor

• Dr. Mazdak Khajehpour

Specific Ion Effects on Micellization

• f a Non‐Ionic Surfactant

4:00 Close Refreshments Parker 256

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Determination of the Compatibility of Current Forensic Collections & Analysis with GC‐MS Techniques for Latent Fingerprints

Ashley Gordon

Supervisor: Dr. Gregg Tomy

Abstract:

Since the 20th century, police have collected fingerprints in an attempt to solve crimes. During this time, physical and chemical techniques have been utilized to visualize latent fingerprints (LFP) to the naked

• eye. Within the last decade, technology has developed to the point where the chemical components

that compromise LFP can be analyzed and quantified. LFP is a combination of eccrine and sebaceous gland secretions containing water, amino acids, lipids, urea, salts, etc. The purpose of this study was to determine if current forensic techniques to visual LFP is compatible with residue analysis by gas chromatography mass spectrometry (GC‐MS). This was achieved by first generating electron ionization (EI) full‐scan mass spectra of all the analytes under investigation including a suite of amino acids, fatty acids, urea, cholesterol, squalene and lactic acid. The two most unique and abundant ions from the EI full scan mass spectrum of each analyte were selected and used in the final selected ion monitoring (SIM) method. Finally, authentic fingerprints samples were obtained from donors by pressing their dominate thumb onto a glass slide. Fingerprint powder, cyanoacrylate superglue and a ninhydrin analog were each applied to the LFP and tested using the developed extraction and GC‐EI‐SIM‐MS method.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

New Catalyst Designs for the Electrochemical Reduction of CO2

David Smith

Supervisor: Dr. David Herbert

Abstract:

Carbon dioxide, believed to be a major contributor to climate change, is constantly being emitted into the atmosphere due to a heavy reliance on fossil fuels for energy production. Being able to convert CO2 back into usable fuels would decrease net emissions and allow for a carbon‐neutral source of energy. Being a stable linear molecule with strong double bonds, it is difficult to accomplish this. An effective electrocatalyst could allow one to reduce CO2 and transfer energy from renewable electric sources into fuels that can be burned as traditional fossil fuels. An effective catalyst would require that the CO2 be bound so that an efficient electron transfer could occur. Some potential catalysts use late transition metals to bind the CO2 molecule, with hydrogen bonds helping to stabilize the bound CO2. Synthesizing a catalyst containing a late transition metal, along with a redox inactive Lewis acid could allow for stronger binding and more efficient electron transfer to reduce the required energy for CO2 reduction. Efforts towards including pnictogen elements as Lewis acidic additions to a ligand set for a Nickel based electrocatalyst will be discussed.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Identification of proteins associated with Connexin36 using mass spectrometry

Swai Mon Khaing

Supervisors: Dr. James Nagy, Dr. Hélène Perreault

Abstract:

Identification of protein interaction networks using mass spectrometry is a powerful approach to gain understanding of complex protein systems in mammalian central nervous system (CNS). Electrical synapses between neurons in the mammalian CNS are formed by gap junctions composed mainly of the gap junction‐forming protein connexin36 (Cx36). In this study, lysates of HeLa cells stably transfected with Cx36 (HeLa‐Cx36) were immunoprecipitated (IPed) with anti‐Cx36 antibodies. The presence of Cx36 in the IP samples was confirmed by immunoblotting. Identification of proteins that co‐IPed with Cx36 was achieved by subjecting samples to in‐gel or on‐bead tryptic digestion followed by matrix‐assisted laser desorption/ionization mass spectroscopy (MALDI‐MS). Although database analysis of MALDI‐MS data did not indicate peptides for Cx36 in any of the samples, it did however reveal the presence of peptides from several other proteins, including those that matched the E3 ubiquitin ligase smad regulatory factor‐2 (SMURF2). SMURF‐2 was recently shown to be recruited to gap junctions composed

• f another member of the connexin family of proteins, namely connexin43 (Fykerud et al, 2012).

Subsequent immunofluorescence showed co‐localization of Cx36 with SMURF‐2 in HeLa‐Cx36 cells. This finding calls for further research to understand SMURF‐2 interactions with Cx36 in HeLa‐Cx36 cells.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Synthesis and Structural Characterization

• f Ca(1‐x)SrxIn2O4 (0 ≤ x ≤ 1)

James Lloyd

Supervisor: Dr. Mario Bieringer

Abstract:

Photoluminescent materials are used in LED displays and are often rare earth cation doped metal oxide host structures. One such example is the rare earth doped CaIn2O4 and SrIn2O4 host structures1. Despite the large volume of research published regarding the photoluminescent properties of these rare earth doped phases, little work has been devoted to the parent oxides. The literature even contains conflicting structural reports for CaIn2O4

2,3 and even more surprisingly, the solid solution Ca(1‐x)SrxIn2O4 (0≤x≤1) has

never been reported. The expected solid solution will provide an opportunity to tune the photoluminescent properties by means of controlling the host lattice. Here the synthesis and structural characterization of the solid solution of Ca(1‐x)SrxIn2O4 (0≤x≤1) is reported for the first time. Powder X‐ray diffraction techniques were used to follow the synthesis, identify products and clarify structural details

• f these phases. The research addresses the synthesis conditions and the structural evolution of the

solid solution, details regarding Ca2+/Sr2+ cation ordering and the potential presence of competing phases will be presented as well.

1) Li T., Guo C., Yang Y., Li L., Zhang N., Acta Materialia 2013, 61, 7481‐7487 2) Cruickshank F., Taylor D., Glasser F., J. Inorg. Nucl. Chem. 1964, 26, 937‐941 3) Reid A., Inorg. Chem. 1967, 6, 631‐633

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Recombinant Expression of the RHAU Helicase protein in E. coli

Ewan McRae

Supervisor: Dr. Sean McKenna

Abstract:

Quadruplexes are polynucleotide structures comprised of base stacked planar disks of four Hydrogen‐ bonded Guanine residues with central monovalent cations. The combination of base stacking (pi‐pi stacking) with the four hoogsteen type hydrogen bonds in each disk makes for a highly thermodynamically stable structureI. These secondary structures are often found in non‐coding regions

• f DNA and RNA which are important for regulating the further transcription and translation of the
• geneII. The protein RHAU (RNA Helicase associated with AU‐rich elements) is a helicase enzyme which

can unwind both DNA and RNAIII quadruplexes and thus has the potential to be an important player in the regulation of gene expression. So far the work which has been done to characterize the activity of the RHAU protein domains has only been done with an isolated N terminal, so called, RHAU specific motif (RSM) which is believed to be the critical component for quadruplex bindingIV. Our current work aims to express soluble, properly folded, and thus active, RHAU proteins in high yield using E.coli as a recombinant vector. We focus on the expression of an almost full length protein,missing only the glycine rich N terminal sequence before the RSM, (Amino Acids 53‐1008) since it has the highest chance

• f retaining RNA/DNA quadruplex activity. We are also working to create truncated versions of the

RHAU protein which lack certain functional regions, this will help to deduce which regions are essential for activity.

I ) Burge, S.; Parkinson, G. N.; Hazel, P.; Todd, A. K.; Neidle, S. "Quadruplex DNA: Sequence, topology and structure". Nucleic Acids Research ; 2006; 34 (19): 5402–5415 II ) Huppert, J. L.; Balasubramanian, S.; "Prevalence of quadruplexes in the human genome" ; Nucleic Acids Research ; 2005 ; 33(9): 2908–2916 III ) Vaughn, J. P., Creacy, S. D., Routh, E. D,, Nagamine, Y., and Akman, S. A. “ G4 Resolvase 1 Binds both DNA and RNA tetramolecular quadruplex with high affinity and is the major source of tetramolecular quadruplex G4‐DNA and G4‐RNA resolving activity in HeLa cell lysates” ; Journal of Biological Chemistry ; 2008 ; 283:34626‐34634 IV ) M. Meier, T. Patel, E. Booy, O. Marushchak, N. Okun, S. Deo. R. Howard, K. McEleney, S. Harding, J. Stetefeld, S. McKenna. ; “Binding of G‐ Quadruplexes to the N‐terminal Recognition Domain of the RNA Helicase associated with AU‐rich element (RHAU)” J. Biological Chemistry ; 2013 V ) G‐Quadruplex Image from : Nancy Maizels ; “Dynamic roles for G4 DNA in the biology of eukaryotic cells” ; Nature Structural and Molecular Bology ; 2006; 13(12) 1055‐1059

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Rotational Levels within the Vibrational Spectra

• f Thietane and Oxetane

Sterling Desmond

Supervisor: Dr. Jennifer van Wijngaarden

Abstract:

Thietane (C3H6‐S) and oxetane (C3H6‐O) are four‐membered ring molecules with low‐lying vibrations involving the motion of their heaviest atom in the ring backbone. The difference in the heavy atom between these two molecules causes extreme effects on the patterns of their spectra, in turn affecting the physical and chemical properties of their rings. In order to analyze these diverse affects, rotationally resolved far‐infrared spectra of thietane and oxetane were recorded using the far infrared light from the Canadian Light Source (CLS). Currently, analysis of thietane’s in‐plane vibrational band (a‐type) at 530 cm‐1 is underway with the current assignment of 2358 lines (1179 rotational‐vibrational transitions). An asymmetric top Hamiltonian was used to perform a fit of the assigned transitions and for the first time, precise highly resolved rotational constants as well as quartic centrifugal distortion constants were

• btained for the investigated band. To compliment the infrared study of thietane and oxetane, the pure

rotational spectrum of both molecules were investigated using our custom‐built high resolution Fourier Transform Microwave spectrometor. Rotational transitions belonging to four isotopic species (parent,

13C(2), 13C(3), 34S and 18O respectively) were recorded and fitted using an asymmetric top Hamiltonian

for thietane and a symmetric top Hamiltonian for oxetane.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Development of immunoglobulin G modified silica beads as a novel stationary phase for glycopeptide enrichment

Katherine Cordova

Supervisor: Dr. Hélène Perreault

Abstract:

Glycosylation is a significant form of post‐translational modification that regulates numerous biological functions of proteins, such as cell signalling, binding affinity, and protein folding. Variations in the glycan forms have notably been observed in several diseases, including cancer. As such, glycopeptides serve as a significant source of potential biomarkers for diagnosis, or disease progression. In order to elucidate structure function correlations, glycopeptide profiling is required. Typical sample mixtures are complex in nature however, with glycoforms being hindered by higher concentrated proteins. Thus, chromatographic purification is often necessary before structural characterization through mass spectrometry (MS). Our goal was to produce a novel glycopeptide‐modified resin, study its enrichment properties of glycopeptides from complex digests, and compare its enrichment capabilities with a resin modified with the peptide’s unglycosylated form. It is expected that the glycan moieties on the resin‐ bound glycosylated sequence should selectively retain glycopeptides in mixtures via strong hydrogen bonding between hydroxyl groups. We chose the glycopeptide segment of immunoglobulin G (IgG) consisting of the sequence: EEQYNSTYR. Using aminopropyl silica beads as a resin, synthesis of the unglycosylated form was achieved with solid phase peptide synthesis based on the Fmoc strategy. Under tryptic digestion, the peptide was then cleaved from the beads, and desalted with a C18 column before MS analysis for sequence verification. Preliminary separation results, using digested enterococcus gallinarum (Eg2) as sample, are examined.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Formation of a Conducting Polymer‐WO3 Bulk Heterojunction for Resistive Memory

Patrick Giesbrecht

Supervisor: Dr. Michael Freund

Abstract:

Due to the physical limit observed in modern‐day Si‐based transistor memory systems, alternative approaches to memory storage are of great interest. One approach that has garnered much enthusiasm is resistive memory, where the high and low states (1,0) depend on the high and low conductive states

• f the system. This system offers the potential for a larger bit density, with a facile fabrication process.

Previous work in the group has developed such a system using a reduced conducting polymer, poly(pyrrole) dodecylbenzylsulphonate (PPyLi+DBS‐), and oxidized WO3 films, with this configuration defining the low state. The high state is achieved through Li+ motion into the WO3 film, oxidizing the polymer while simultaneously reducing WO3, increasing the conductivity of each film. Unfortunately, this memory system exhibits slow ion motion, setting a limit on its switching dynamics between high and low states. One possible solution is to increase the interfacial surface area between the films, forming a bulk heterojunction‐like system, where faster switching dynamics due to a reduced ion diffusion length between the films is predicted. In this work, a junction has been developed, where a porous WO3 film was formed, allowing polymer deposition into these features. The structure of this composite was analyzed under scanning and transmission electron microscopy, showing the porous nature of the WO3 film, as well as the polymer incorporation into the film. The solution‐based and solid‐state electronic properties of the composite were also tested, with memristive behavior and faster ion motion observed in the solid state.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Synthesis and Characterization

• f Rhodium β‐diiminate Complexes

Rebecca Sherbo

Supervisor: Dr. Peter Budzelaar

Abstract:

Transition metals have proven their utility in a wide variety of catalysts for a vast array of chemical transformations.1 Rhodium has been found to be very reliable in transition metal catalysis. Since the development of one of its earliest uses as an olefin hydrogenation catalyst2, the number of possibilities for this metal has become huge due to its ability to change oxidation state and coordination number

• easily. β‐diiminate ligands are bidentate nitrogen donors that can be used in concert with the rhodium

metal center. They possess a number of advantages including the ability to stabilize reactive complexes that can go on to do further chemistry with the added benefit of studying steric effects while minimizing

• ther variables.3 In this project, a new β‐diiminate ligand was synthesized and characterized. It was then

used in two contexts. The first was to explore the activation of silanes and other group 14 substrates. Similar complexes have previously shown to intramolecularly activate silanes4 and this type of activation has still yet to be accomplished intermolecularly. A variety of substrates were tested and some new reactive germanium complexes were identified. The second is understanding rhodium complexes of

• dienes. These diene complexes show selective isomerization which may be of interest in organic
• transformations. They also show fluxional behaviour when monitored by NMR that may fundamentally

change how we understand changes in geometry and rotation in square planar complexes.

• 1. Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, 2007
• 2. Osborn, J. A., Jardine, F. H., Young, J. F., Wilkinson, G. J. Chem. Soc. A., 1966, 1711‐1732
• 3. Zhu, D., Budzelaar, P. H. M. Dalton. Trans. 2013, 42, 11343‐11354
• 4. Zhu, D., Kozera, D. J., Enns, K. D., Budzelaar, P. H. M. Angew. Chem. Int. Ed., 2012, 51, 12211‐12214

R h N N H 3C C H 3 Ar Ar H H G e Et 3 G e E t 3 H 3C C H 3 N N Ar R h G e Et 2 H H G e E t 3 C H 3 C H 3

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Synthesis of Antimicrobial Peptides Containing Pro‐Arg‐Pro Repeating Motifs

Benchmen Choun Trieu

Supervisor: Dr. Frank Schweizer

Abstract:

Antimicrobial peptides (AMPs) are known to have antimicrobial and immunomodulatory properties. A class of Proline‐Rich Antimicrobial Peptides (PR‐AMPs) have been recently considered as potential agents for treating Gram‐negative bacterial infections. This is due to their high selectivity towards these cells and most importantly the non‐membranolytic mode of action. Several members of this class of PR‐ AMPs, found in insects, contain multiple copies of repeating Proline‐Arginine‐Proline (PRP) motifs.[1,2] Studies have shown this tripeptide sequence to be important for the antimicrobial function.[3] This study will involve the synthesis of a nonapeptide containing three PRP motifs. The N‐terminus of the peptide will be capped by condensation to a fatty acid (nonanoic acid) to facilitate anchoring of the peptide in bacterial membranes. Synthesis includes producing the trimer in a large‐scale followed by Solid Phase Peptide Synthesis (SPPS). Some physical properties of the products made will also be discussed.

N O H N NH NH HN O N COOH Fmoc Pbf N O H N NH NH2 HN O N (H2C)7 O CH3 O NH2

3

[1] Otvos, L.Jr. Cell. Mol. Life Sci., 2002, 59, 1138‐1150 [2] Scocchi, M., Tossi, A., Gennaro, R.; Cell. Mol. Life Sci. 2011, 68, 2317‐2330 [3] Lele, D.S.; Talat, S.; Kaur, K.J. Int. J. Pept. Res. Ther. 2013, 19, 323‐330

Figure 1: Displays the characteristic crystal phases of the silicon microwires grown in the Si<111> direction

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Functionalization and Characterization

• f Representative Model Crystal Surfaces
• n Silicon Microwires

Heather Cavers

Supervisor: Dr. Michael Freund

Abstract:

In recent years the use of silicon microwire arrays as the photoelectrode material in artificial photosynthetic devices has been found to increase the efficiency of these devices, with less of the current produced depleted from internal losses and the light absorption maximized. However, there are still many issues that impact the overall efficiency of devices constructed with these structures, not the least of which is the ease of oxidation of silicon. One surface passivation method is to terminate the surface sites with a methyl group, allowing resistance to oxidation while conserving charge transfer capabilities. This has been well characterized for single crystal Si(111), but silicon microwires possess other crystal faces besides (111) (Figure 1), in addition to the presence of facets or surface defects, with differing atomic surface densities and bonding characteristics. In order to investigate how these differences manifest themselves, methyl terminated silicon (111), (110) and (211) surfaces representative of the microwire faces were investigated with X‐ray Photoelectron Spectroscopy. Using this technique the surface coverage and

• xide growth of the difference silicon surfaces were investigated and compared. Furthermore, the

impact of the presence of contaminants on the amount of methyl terminated sites could also be

• determined. In addition, depth profiling of the surfaces was performed with XPS using ion gun

experiments in order to examine the impact of the adventitious carbon on the characterization of the Si‐ C peak.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Purification and crystal screening of the cytoplasmic tail segment of a K+/H+ antiporter from Vibrio cholerae

Roy Hutchings

Supervisor: Dr. Jörg Stetefeld

Abstract:

Cation‐proton antiporters are critically important membrane proteins that function to transport H+ and a specific cation (such as K+, Na+, or Li+) in opposite directions across a cell membrane. NhaP2 is a potassium/proton antiporter found in the bacterium Vibrio cholerae. While its mechanism of ion‐ specificity remains a mystery, of particular interest is its C‐terminal cytoplasmic tail. This soluble segment is predicted to have significant domain architecture, potentially making Vc‐NhaP2 the only known prokaryotic antiporter with a cytoplasmic tail that contains any form of domain architecture. In this project, we attempted to characterize the cytoplasmic tail by x‐ray crystallography. Recombinant VcNhaP2 C‐terminal tail segment was cloned into Escherichia coli and expressed with a polyhistidine tag. The protein was purified by immobilized metal ion affinity chromatography and gel filtration chromatography to prepare for biophysical characterization. Several crystallization conditions were screened to crystalize the protein for structure determination by x‐ray diffraction, but have so far yielded no hits.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Computational Study of a Binuclear Pentavalent Uranyl Complex in a Schiff‐Base Polypyrrolic Macrocycle

Shaun MacLean

Supervisor: Dr. H. Georg Schreckenbach

Abstract:

A recently synthesized silylated binuclear uranium(V) dioxo complex displayed surprising stability, notably in a distinct Pacman‐shaped structure [1]. Desilylation promotes reactivity of this species, noted as cis/trans‐oxo rearrangements. In this study, a detailed computational analysis using relativistic density functional theory (DFT) has been performed on these Pacman complexes, and on the rearranged products in particular, in order to determine characteristics such as electronic and geometric properties. The subsequent comparison of these properties was used to better understand the stability of the uranium(V) complex, as well as factors that contribute to the rearrangement of the complex into the linear uranyl geometry. Trends between the protected and unprotected complexes were analysed for the fundamental differences that lead to rearrangement as induced by oxo‐group functionalisation. This study has been extended to neptunium and plutonium complexes, as well.

[1] Jones et al. Angew. Chem. Int. Ed. 2012, 51, 12584.

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

FTIR spectrochemical analysis of nutritional composition of the diatom Fragilaria cylindrus after exposure to varying light levels

Alexandra C. Ciapala

Supervisor: Dr. Kathleen M. Gough

Abstract:

Diatoms are an incredibly diverse type of algae best known for their intricately detailed frustules composed of silica. Sea ice diatoms live in the brine‐filled pores of the arctic ice and form vast blooms in the spring. They are one of the major primary producers in the arctic ecosystem and a staple food source for aquatic life, thereby holding a key position in the arctic food web. With global climate change comes concern for the impact on animal habitats. Arctic temperatures are rising, ice is melting faster and earlier, and diatoms are experiencing abnormal light exposure. In this study, the biochemical effect

• f light exposure on the arctic sea‐ice diatom Fragilaria cylindrus was investigated using Fourier

Transform infrared (FTIR) vibrational spectroscopy. It was hypothesized that increasing light levels would stimulate growth, resulting in a decreased lipid to protein ratio until an intensity was reached that resulted in photo‐inhibition. FTIR is a fast, non‐destructive technique ideally suited to probing the diatom samples. The frequency of IR light absorbed depends on the masses of the atoms vibrating, the bond strengths, and the nature of the vibration. Consequently, certain functional groups absorb at characteristic ‘group frequencies’, allowing us to probe the samples composition. Here, cultures were acclimated to normal light levels (~30 mol photons/m2s1) then grown at 5 different light levels: 0, 10, 30, 120, and 330 mol photons/m2s1. Samples from each were collected over a period of two weeks in

• rder to monitor the initial stress reaction and subsequent adaptive response, if any. The integrated

FTIR absorbance intensities, which are proportional to abundance, of the bands for fatty acid (CH2 stretch) and protein (amide1 band) were chosen as biomarkers reflecting nutritional value and growth

• rate. Spectra were collected from small clusters of diatoms and (CH2): (Amide 1) was calculated, making

analysis independent of the number of diatoms viewed. Preliminary results show an increase in (CH2): (Amide 1) during initial adaptation for the 330 mol photons m‐2s‐1 condition, suggesting a decrease in growth rate as stress responses are triggered. There is a subsequent decrease in (CH2): (Amide 1) at later time points, suggesting that adaptation had occurred and the growth rate had increased.

Cluster of diatoms (left) visible light, (middle) infrared absorbance spectrum, and (right) false colour, showing integrated intensity of CH2 band from low to high (blue – red ).

CHEM 4710 2013‐2014 Honours Research Project in Chemistry or Biochemistry

Specific Ion Effects on Micellization

• f a Non‐Ionic Surfactant

Hayden Glor

Supervisor: Dr. Mazdak Khajehpour

Abstract:

Specific ion effects on protein interfaces have been observed for many years. These effects are typically seen in the form of protein precipitation from solution by small, hard ions, while larger ions of more diffuse charge tend to denature and stabilize the unfolded protein in solution. Although specific ionic effects at protein interfaces have been known for some time, little information regarding the mechanisms by which ions interact with proteins and more general aqueous interfaces have been

• btained. However, a sizeable quantity of data has been collected on ionic effects at the air‐water
• interface. In this work the effects of different ions on the critical micelle concentration (CMC) of 1,2

Hexanediol, an oil‐water interface, have been examined. A linear relationship between the ion concentration and the change in free energy of micelle formation is observed for various ions of both positive and negative charge. This linear relationship, known as the Micellization Free Energy Increment (MFI), was compared to Surface Tension Increments (STI) obtained for specific ions by Marcus, where the change in surface tension of water is dependent on the concentration of the specific ion in the

• solution. The effect of ions on surface tensions has been explained by the difference of ions partitioning
• ut of the air‐water interface and into the bulk solution. Pegram and Record have interpreted this and
• ther ion specific interfacial phenomena in terms of partitioning coefficients. Results from the present

study show that correlation between MFI and STI is not always reliable. Rather than following a partitioning model between the interface and bulk solution, the MFI values seem to correlate better with Scaled Particle Theory, in which specific ionic effects are thought to take place in the bulk solution rather than at the interface. Specifically how the ions affect the free energy of cavity formation in solution, which should be minimized for micelle formation.

Formation of a micelle at the critical micelle concentration.