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Macromolecular Chemistry: The Second Century Opening Keynote Session:  
07:00am - 09:40am USA / Canada - Pacific - April 5, 2021
Timothy Lodge, Organizer; Krzysztof Matyjaszewski, Organizer; Alvin Collins, Presider
Track: [MPPG] Multidisciplinary Program Planning Group
Division/Committee: [MPPG] Multidisciplinary Program Planning Group
Monday
Introductory Remarks
07:00am - 07:05am USA / Canada - Pacific - April 5, 2021
Track: [MPPG] Multidisciplinary Program Planning Group

Monday
Supramolecular polymerization: Its significance and applications
07:05am - 07:55am USA / Canada - Pacific - April 5, 2021
Takuzo Aida, Presenter
Track: [MPPG] Multidisciplinary Program Planning Group
About a century ago, Dr. Staudinger substantiated the existence of ultralong molecules and won the long-term debate against the colloidal theory to establish polymer science. Needless to say, polymer science has made tremendous contributions to the progress of human society, although it coincidentally brought about a critical environmental issue to tackle. In this lecture, I would like to present the significance and applications of supramolecular polymerization, a modernized version of the colloidal approach to polymeric materials. Supramolecular polymers attract attention not only because they are 100% recyclable but also they can be designed to be eco-friendly, self-healable, responsive, and adaptive [1–4]. In 1988, we reported the prototype of supramolecular polymerization using an amphiphilic porphyrin with water-soluble oligoether side chains as the monomer and have made fundamental contributions to this field. Representative examples include (1) nanotubular supramolecular polymerization, (2) chain-growth supramolecular polymerization, (3) supramolecular block copolymerization, (4) stereoselective supramolecular polymerization, and (5) thermally bisignate supramolecular polymerization. These contributions are integral elements of conventional polymer science, filling in the critical gap between supramolecular and conventional polymerizations. Furthermore, we have expanded the basic concept of supramolecular polymerization into the noncovalent design of innovative soft materials. Successful examples include the developments of (i) bucky gels, (ii) aquamaterials, (iii) mechanically robust self-healable materials, (iv) supramolecular polymers of biomolecular machines, (v) ferroelectric columnar liquid crystals, and (vi) reorganizable and adaptive core-shell columnar liquid crystals. I will highlight some of these examples to show the significance of supramolecular polymerization for the realization of sustainable society.

Monday
Polymer networks as synthetic extracellular matrices: Biology in the 4th dimension
07:55am - 08:45am USA / Canada - Pacific - April 5, 2021
Kristi Anseth, Presenter
Track: [MPPG] Multidisciplinary Program Planning Group
Our group is interested in the development of macromolecular monomers that can be reacted into crosslinked polymer networks in the presence of living cells and tissues. From a fundamental perspective, we seek to decipher the critical extracellular matrix (ECM) signals that are relevant for tissue development, regeneration, and disease and then design polymeric materials that integrate these signals. From an applied perspective, we use this knowledge to design materials that can promote tissue regeneration and wound healing in vivo. This talk will illustrate our recent efforts towards the synthesis of hydrogel networks for 4D cell culture and regenerative medicine, and how one can dynamically control biochemical and biophysical properties through orthogonal, photochemical click reaction mechanisms. Some specific examples will include the design of hydrogels that promote musculoskeletal tissue regeneration, super-swelling matrices to visualize cell-matrix interactions with unprecedented resolution, and materials-directed growth of organoids from single stem cells. These efforts will then be placed in the context of designing precision biomaterials to address demands for patient specific products and treatments.
Monday
Neofossils: bio-based plastics to sequester CO2
08:45am - 09:35am USA / Canada - Pacific - April 5, 2021
Track: [MPPG] Multidisciplinary Program Planning Group
The news is full of the evils of plastic. But plastic can’t be evil, it’s inanimate. It’s plastic abuse that is morally wrong. In the 100 years since the macromolecular hypothesis we have produced more than 8 billion tons of the stuff vilified as “plastic”. The ingenuity of polymer scientists & engineers, plus the ubiquity and variety of polymers, mean they are completely embedded in our lives. But the very properties of plastics that make them so useful, they are durable & cheap, also means that they almost worthless post-use, expensive to recycle & easy to discard.

We need to focus on delivering a circular economy for polymers, whether they are derived from fossil carbon or more recent biomass. A systems-based, multidisciplinary approach can solve the problem of plastics in the environment through a combination of reuse, repurposing & recycling. Bio-based & compostable plastics are not inherently sustainable because their production can cause more greenhouse gas emissions than the fossil-based plastics they replace. Moreover, the fate of a compostable plastic is conversion back into CO2 & water. Bio-based plastics can only become truly sustainable when produced using renewable energy, not the current energy mix of >80% fossil. Life cycle assessment can identify the tipping point, as the energy system defossilises, when making durable bio-based plastics for a circular economy makes sense.

The Intergovernmental Panel on Climate Change (IPCC) has a 1.5 °C target with a commitment to the removal of 12 billion tons of CO2 per year, >25% of current emissions, yet there are no scaleable technologies to do this. Herein lies an opportunity for the next 100 years of polymer science. We could use durable (i.e. nondegradable) bio-sourced plastics to sequester carbon. Making polymers from photosynthetic biomass takes CO2 out of the atmosphere and we could bury that plastic. In fact, if we converted all the current 300 million tonnes of annual plastic production to non-degradable bioplastics, using 100% renewable energy and agricultural waste as the feedstock, we would be able to remove a billion tonnes of CO2 from the atmosphere every year.

Negative carbon emissions from plastic production and consumption would mean we become heroes again. We could put that new plastic down the holes we got the fossilised carbon out of in the first place – wouldn’t that be sweet!

Monday
Concluding Remarks
09:35am - 09:40am USA / Canada - Pacific - April 5, 2021
Track: [MPPG] Multidisciplinary Program Planning Group

Aqueous Normal Phase Chromatography Using Silica Hydride-Based Stationary Phases:  
09:00am - 12:00pm USA / Canada - Pacific - April 5, 2021
Rafea Naffa, Organizer, Presider; Dr. Joseph Pesek, Organizer, Presider
Track: [ANYL] Division of Analytical Chemistry
Division/Committee: [ANYL] Division of Analytical Chemistry

Aqueous normal phase chromatography and silica hydride-based stationary phases are a developing technology with a broad range of applications. The symposium will focus on understanding the basic principles of the technique as well as current investigations utilizing this technology.

Monday
Introductory Remarks
09:00am - 09:03am USA / Canada - Pacific - April 5, 2021
Track: [ANYL] Division of Analytical Chemistry

Monday
Five years with silica hydride column: Analysis of collagen crosslinks and advanced glycation end products
09:03am - 09:38am USA / Canada - Pacific - April 5, 2021
Track: [ANYL] Division of Analytical Chemistry
Collagen is the most abundant protein in animals and is a basic building block within almost every organ or tissue. It is an essential component of the extracellular matrix which provides strength and elasticity to tissues that possess a mechanical function such as bones, tendons, and cartilage. The collagen macro-structure is stabilised by covalent crosslinks and any alteration in their biosynthesis can lead to several diseases including bone fragility, skin hyperelasticity, and cardiovascular diseases. Upon ageing, collagen undergoes further modification by sugar metabolites resulting in the formation advanced glycation end products that are linked to the decreasing mechanical strength of collagen.
The analysis of collagen crosslinks and advanced glycation end products has proven to be challenging due to their high hydrophilicity. They were historically analysed by cation exchange and reverse phase chromatography, methods not conducive to their simultaneous and rapid analysis in biological tissues. To overcome these problems, we developed a rapid method for the analysis of collagen crosslinks and advanced glycation end products using silica hydride column chromatography. Separation is achieved under 5 minutes using water and methanol or acetonitrile as the mobile phase,without any need for ion pairing agents or buffer salts. More importantly, the method is compatible with UV, fluorescence and mass spectrometry detection. Cross links in a number of different biological samples were analysed using this method and the results have led to an enhanced undersatanding of possible biosynthetic pathways and control mechanisms for the biosynthesis of these crosslinks, as well as the possibility of identifying new cross links.

Monday
Flip flop chromatography using silica hydride based stationary phases for the separation of synthetic cathinone positional isomers
09:38am - 10:13am USA / Canada - Pacific - April 5, 2021
Track: [ANYL] Division of Analytical Chemistry
Novel psychoactive drugs (NPS) are a range of drugs that have been designed to mimic established illicit drugs, such as cannabis, MDMA, cocaine and LSD, and as such circumvent existing laws. Positional isomers of NPS are difficult to analyze because they challenge the separation and detection techniques commonly employed by forensic laboratories. Flip flop chromatography is a liquid chromatography technique whereby a single column is utilized for the same analyte(s) in two different separation modes, without the need to change solvent reservoirs. In this vein the utility of silica hydride (SIH) stationary phases, operable under both reversed phase (RP) and aqueous normal phase (ANP) conditions, for the ultra-high performance liquid chromatography separation of synthetic cathinone positional isomers will be presented. The separation of eight positional isomers of the synthetic cathinone pentedrone, was investigated using five SIH phases, and compared to the use of a bimodal pentaflurophenyl column and utilizing a classical dual column RP, hydrophilic interaction chromatographic (HILIC) system. The silica hydride silica-C column, which contains no derivatized ligands attached to the silica hydride backbone, not only gave the most uncorrelated separation of the SIH columns but provided a unique separation of all eight positional isomers (resolution ≥ 1) using the combination of RP and ANP chromatographic conditions. The use of SiH phases, in contrast to the use of a classical RP column and a classical silica column operating under HILIC conditions, allows for rapid equilibration times for both RPC and ANP without the necessity of changing columns.
Monday

The characterization of highly flavored tobacco products such as e-liquids and contemporary shisha tobaccos presents a major analytical challenge. In the case of e-liquids (also known as electronic cigarette refill liquids), the matrix is a mixture of glycerol and propylene glycol that may also contain nicotine and/or water. The matrix for contemporary shisha tobaccos generally has glycerol as the main component, followed by propylene glycol, sugar syrups, water, and only 10 – 30% tobacco. Flavorings are usually added as solutions in propylene glycol. A number of popular flavors are aromatics or aliphatic aldehydes and these react with the propylene glycol and glycerol in the formulations. Thus, for example, vanillin forms two diastreomers with propylene glycol and several with glycerol. Since such acetals may not have enough thermal stability for gas chromatography, liquid chromatography is preferred. However, conventional reverse phase chromatography often results in numerous coeluting peaks. aqueous normal phase chromatography using bidentate -18, phenyl hydride, diol, and amide hydride phases minimizes such problems. Typical mobile phases are acetonitrile-water-0.13% TFA at 1 mL/minute with 250 x 4.6 mm columns. UV detection at several wavelengths was used to help determine coelutions.

Monday
Retention behavior of temozolomide and its impurities under reversed phase and aqueous normal phase conditions
10:48am - 11:23am USA / Canada - Pacific - April 5, 2021
Dr Mark Powell, Presenter
Track: [ANYL] Division of Analytical Chemistry
Temozolomide is an antineoplastic drug used orally to treat some brain tumors such as glioblastoma multiforme and malignant glioma which has not responded to first-line chemotherapy. The principal hydrolysis product of temozolomide is Impurity A (Figure 1). This compound is poorly retained by reversed-phase (RP) HPLC; compendial methods employ an ion pair reagent (5 mM sodium 1-hexanesulfonate) to achieve adequate retention. Depending on the drug product matrix, ion-pair HPLC can exhibit poor robustness and ANP chromatography was evaluated as an alternative.

A Cogent Diamond Hydride column and an isocratic mobile phase comprising different proportions of water and acetonitrile, acidified with 0.1 % acetic acid was used for the study. Impurity A was well retained at high acetonitrile concentrations (ANP conditions). At lower acetonitrile concentrations (RP conditions), the retention of a different impurity (Impurity C) improved. Retention time data under ANP conditions are shown in Table 1. Retention mechanisms under ANP and RP conditions are discussed.
Figure 1.  Impurity A

Figure 1. Impurity A

Table 1.  Retention times at different mobile phase compositions

Table 1. Retention times at different mobile phase compositions


Monday
The unique chromatographic properties of type C silica (silica hydride)
11:23am - 11:58am USA / Canada - Pacific - April 5, 2021
Track: [ANYL] Division of Analytical Chemistry
Type C silica, based on a surface that contains in excess of 95% silica hydride (Si-H) in contrast to ordinary silica that has silanol (Si-OH) groups, is increasing becoming a more common HPLC stationary phase column material because of its numerous chromatographic advantages. A fundamental difference between the two materials is the strongly polar nature of ordinary silica vs. the mildly hydrophobic characteristic of silica hydride. This property results in a very thin water layer on the surface of the stationary phase. In high organic mobile phase compositions, auto dissociation of water provides hydroxide ions on silica hydride creating a polar surface for the retention of hydrophilic analytes. The absence of a water layer on the surface of the stationary phase results in reproducible retention of polar compounds and fast equilibration with gradient mobile phase methods. Thus, any silica hydride-based stationary phase can operate in either the reversed-phase or normal-phase (organic or aqueous) modes. For polar compounds using aqueous normal phase instead of HILIC provides many benefits including the requirement for only low concentrations of additive in the mobile phase to produce substantial retention. This property is particularly beneficial when mass spectrometry is used for detection. Overall Type C silica hydride stationary phase are superior to mixed-mode phases which will be illustrated in applications that include analyses of biological, forensic, food, clinical and pharmaceutical samples.
Monday
Concluding Remarks
11:58am - 12:00pm USA / Canada - Pacific - April 5, 2021
Track: [ANYL] Division of Analytical Chemistry

Division of Biological Chemistry National Awards:  
09:00am - 12:00pm USA / Canada - Pacific - April 5, 2021
Mark D Distefano, Organizer, Presider; Ekaterina Pletneva, Organizer, Presider
Track: [BIOL] Division of Biological Chemistry
Division/Committee: [BIOL] Division of Biological Chemistry

This symposium honors members of the Division of Biological Chemistry who have won National Awards from the American Chemical Society. The speakers are all award winners.

Monday
Introductory Remarks
09:00am - 09:05am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Monday
Evolving virus-like nucleocapsids from nonviral protein cages
09:05am - 09:35am USA / Canada - Pacific - April 5, 2021
Dr. Donald Hilvert, Presenter
Track: [BIOL] Division of Biological Chemistry
Viruses consist of a protective proteinaceous shell that packages an RNA or DNA genome. The emergence of protein cages that could load, protect, and transfer their own genetic information was therefore likely to be a critical step in the evolution of all primitive viruses. Using a combination of design and directed evolution, this process can now be recapitulated in the laboratory. We have converted the nonviral protein cage formed by lumazine synthase into an artificial nucleocapsid that efficiently encapsulates its own encoding mRNA, and have elucidated the structural changes that made this transformation possible. In addition to providing insight into the origins of natural viruses, such constructs may serve as potentially safe surrogates for diverse nano- and biotechnological applications.
Monday
Introductory Remarks
09:35am - 09:40am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Monday
Targeting heme-fluoride host factors to block viral replication and alert the immune system.
09:40am - 10:10am USA / Canada - Pacific - April 5, 2021
Kevan Shokat, Presenter
Track: [BIOL] Division of Biological Chemistry
The novel coronavirus SARS-CoV-2, the causative agent of COVID-19 respiratory disease is evolving during the current pandemic. New variants show enhanced replication and the potential to evade therapeutic antibodies. In the near future, variants may even evade first generation vaccines. The currently approved direct acting antiviral remdesivir targets the viral RNA-dependent RNA polymerase which is subject to rapid evolution as it is encoded by the viral RNA genome. In order to develop therapeutic approaches which act in a pan-coronavirus manner we and our colleagues at the QBI Coronavirus Research Group (QCRG) have mapped the human proteins (host factors) which multiple Coronaviruses rely on for replication. Through a rapid drug repurposing effort we have identified zotatifin, a clinical eIF4A inhibitor as a host factor targeted therapeutic. Zotatifin which is based on the natural product rocaglamide A works as a molecular glue to trap eIF4A on its target, the (+) RNA viral genome. Other examples of targeting essential host factors, including those for immune evasion will be discussed.

Monday
Introductory Remarks
10:10am - 10:15am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Monday
Coiled coil control of diverse EGFR functions
10:15am - 10:45am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry
EGFR exhibits biased signaling, whereby growth factor or mutation-dependent changes in receptor conformation and/or dynamics elicit distinct intracellular outcomes. We find that many intracellular EGFR outcomes are controlled by a two-state coiled coil switch located within the juxtamembrane segment (JM), an essential component of the cytosolic dimer interface. The position of this switch defines the path of endocytic trafficking, the extent and dynamics of autophosphorylation, c-Cbl recruitment, and ubiquitination, and whether or not EGFR is degraded within lysosomes. It also predicts kinase-independent effects of oncogenic mutations and clinically relevant tyrosine kinase inhibitors (TKIs) that promote lysosome-based degradation. These findings provide a model for biased EGFR signaling, insights into kinase-independent activities of EGFR and clinically relevant TKIs, and identify new strategies for modulating protein lifetime.
Monday
Introductory Remarks
10:45am - 10:50am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Monday
Chemistry of entrepreneurship for developing new medicines
10:50am - 11:20am USA / Canada - Pacific - April 5, 2021
Paul Schimmel, Presenter
Track: [BIOL] Division of Biological Chemistry
Just 40 years ago the US Congress passed a bipartisan bill that transformed the ability of academic scientists to translate their research discoveries into new medicines. Although most universities and their faculties were slow to seize the opportunity, over time the success of a few inspired others. The biotechnology industry that arose had deep roots in NIH-funded research discoveries and overcame deep skepticism from the established pharmaceutical industry that was especially directed towards the broad use of injectable proteins. Most recently that same skepticism faced injectable RNA molecules. But these RNA drugs are expanding widely and have received approvals for broad classes of diseases and as a basis for vaccine production within an organism. Tracing back to the origin of these medicines again shows the role of basic discoveries made in the setting of a non-for-profit institution, and the large benefit to society of a congressional action 40 years ago.
Monday
Introductory Remarks
11:20am - 11:25am USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Monday
Structure, dynamics and mechanism of membrane ion channels from NMR
11:25am - 11:55am USA / Canada - Pacific - April 5, 2021
Prof. Mei Hong, Presenter
Track: [BIOL] Division of Biological Chemistry
Ion channels and transporters carry charged substrates across the hydrophobic barrier of biological membranes for cellular function or microbial infection. This transport requires an exquisitely tuned protein structure as well as protein dynamics. Deciphering both the structure and dynamics of these membrane proteins is necessary for understanding the atomic mechanism of ion transport and for blocking this process in infectious pathogens. Solid-state NMR spectroscopy has emerged as an ideal method to elucidate the atomic structure, dynamics, substrate interaction and mechanism of action of channels and transporters in their native environment of phospholipid bilayers. Using multidimensional and multinuclear (13C, 15N, 19F and 1H) solid-state NMR, we have determined atomic-resolution structures of three ion channels and transporters of viruses and bacteria. The influenza M2 protein forms a tetrameric proton channel to cause virus uncoating. The SARS-CoV-2 envelope protein forms a pentameric cation channel that triggers the cell’s inflammasome. The dimeric bacterial protein EmrE transports cationic polyaromatic substrates to cause multidrug resistance. In influenza M2, the proton-selective residue and the gating residue undergo microsecond motions to shuttle protons, while the protein backbone undergoes slower millisecond motions to limit the proton flux and control the direction of proton current. For the non-selective transporter EmrE, extensive protein conformational dynamics coexists with large-amplitude substrate dynamics. Solid-state NMR data provided not only the atomic structures but also the rates and geometries of protein motions, proton exchange processes, and in some cases, inhibitor binding sites in the viral ion channels.
Monday
Concluding Remarks
11:55am - 12:00pm USA / Canada - Pacific - April 5, 2021
Track: [BIOL] Division of Biological Chemistry

Food-flavor Dynamics Assessments via Real-time Mass Spectrometry: Part I: From Developments to Nosespace
09:00am - 12:00pm USA / Canada - Pacific - April 5, 2021
Jonathan Beauchamp, Organizer, Presider; Yu Wang, Organizer, Presider
Track: [AGFD] Division of Agricultural and Food Chemistry
Division/Committee: [AGFD] Division of Agricultural and Food Chemistry

Flavor perception during food consumption is a dynamic process associated with the release of odor-active (aroma) compounds through mastication. Prior to consumption, the passive release of these volatile compounds into the air impart an aroma impression of the food. While conventional food-flavor analysis, e.g., by gas-chromatography (GC), offer important insights into flavor, such as characterizing key aroma compounds, their limited time resolution make them unsuitable for exploring dynamic processes. This symposium will cover the application of real-time mass spectrometry (MS), in particular proton transfer reaction MS (PTR-MS), atmospheric pressure chemical ionization MS (APCI-MS) and selected ion flow tube MS (SIFT-MS), to characterize food-flavor. The symposium is aimed to cover both in vitro and in vito flavor compound studies. The former includes flavor release in headspace, spoilage-related flavor compounds, or flavor development (e.g., during roasting, baking, etc.), or high-throughput analysis; the latter covers nosespace analysis for retronasal aroma perception, inter-oral analysis, or model-mouth experiments. A direct link to odor perception via complementary sensory analysis is welcome and encouraged. In essence, if you have used a real-time MS technique to characterize flavor release from food – any food or drink – we welcome your contribution!

Monday
Introductory Remarks
09:00am - 09:05am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry

Monday
Atmospheric pressure chemical ionization (APCI) for real-time odor analysis
09:05am - 09:20am USA / Canada - Pacific - April 5, 2021
Andrew Taylor, Presenter
Track: [AGFD] Division of Agricultural and Food Chemistry
The 1990s saw a move to complement the analysis of food flavor composition (using techniques like Solvent Assisted Flavor Evaporation followed by GC-MS), with methods to measure the odor profile released from foods before and during eating. The rationale was that the odor profiles in the headspace and "nosespace" were very different from the compositional profile, due to factors like odor partition and volatility but these were the profiles that actually activated the odor receptors and might help researchers better understand the link between the perceived flavor of a food and its flavor composition. Direct mass spectrometry was an obvious analytical option but presented challenges such as obtaining sufficient sensitivity (odor concentrations in the gas phase are several orders of magnitude lower than in foods), dealing with the high humidity in human breath and collecting data fast enough to accurately map odor release on a breath-by-breath basis. APCI-MS offered many advantages for this analytical task, for example, the ease of interfacing human breath with the hi-vacuum MS using venturi, the fact that water can be used as the charge transfer reagent in APCI (thus humidity of breath samples is not an issue) and the ready availability and simplicity of the APCI interfaces fitted to mass spectrometers. Like all techniques, there were also limitations, some of which could be overcome by "work arounds", others which are inherent to the technique. A description of the APCI ionization process and the design of the interface will be given along with the pros and cons of this technique for monitoring the real-time release of odors from foods.
This presentation is dedicated to my long-term collaborator in the development of APCI-MS, Jun Hatakeyama from Nichirei Foods, Japan, who tragically died in 2020.

Monday
PTR-MS: Sampling matter(s) - from the importance of sample introduction to the diversity of innovative solutions
09:20am - 09:35am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry
The majority of complex scientific data generated in the food, flavor and fragrance research sectors
relies on modern mass spectrometric methods. This is due to obvious advantages in terms of
objectiveness, reliability, comprehensiveness and accessibility. In the early days only experts were
skilled enough to use this technology. But from the first day on, when such complex instruments
started to be well manageable in standard laboratory environments, the success of their applications
never declined. One of the common persistent challenges relates to the introduction of the sample
into the analyzer. Because of its importance, diversity and accumulated knowledge for PTR-MS in this
field, this presentation will provide a short overview about past hurdles, achieved solutions and an
outlook on new developments for flavor-research applications and beyond.

Monday
Comprehensive aroma analysis with selected ion flow tube mass spectrometry (SIFT-MS)
09:35am - 09:50am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry
Selected ion flow tube mass spectrometry (SIFT-MS) is a direct mass spectrometric technique that has contributed significantly to better understanding of food-flavor dynamics in food processing and in vivo studies. In SIFT-MS, rapid switching of multiple reagent ions and cooling of reagent ions to consistent energies before sample introduction, provides speed, selectivity and enables an in-built compound library. This simplifies method development, quantitation and compound identification, making for a more user-friendly experience.

This talk reviews some recent applications of SIFT-MS in food aroma analysis. A few highlights of flavor analysis applications, such as flavor release, sensory, food origins, quality testing and food processing, are discussed. The power of SIFT-MS combined with chemometrics for both targeted and untargeted analysis is also demonstrated.

Packaging can also impact food quality and flavor. While packaging can play a significant role in maintaining food freshness, inferior grade packaging could lead to food taint. SIFT-MS investigations into packaging are discussed, along with the benefits of using automated SIFT-MS to improve both speed and precision of headspace measurements. A recent development – thermal desorption (TD)-SIFT-MS – is also introduced, which adds extra functionality to analysis of packaging materials, by utilizing thermal extraction analysis.

Finally, the potential and future direction of SIFT-MS in food-flavor analysis is presented.

Monday
Molecular mechanisms behind the phenomenon of food aroma persistence
09:50am - 10:05am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry
Aroma persistence plays a major role in food choices and liking, and thus, its understanding might be important to formulate food products sensorially appreciated by consumers. The aim of this work was to unravel the molecular mechanisms behind the phenomenon of aroma persistence by using a global approach. The release and metabolization of 5 food aroma compounds (linalool, pentan-2-one, nonan-2-one, hexan-2,3-dione and octanal) from different chemical classes was studied after their exposure to ex vivo models of oral mucosa (oral cells+saliva) by Gas-Chromatography Mass Spectrometry (GC-MS). Then, in vivo dynamic instrumental and sensory experiments were carried out to validate the ex vivo findings in a more realistic context. To do that, in vivo aroma release was monitored by Proton Transfer Reaction-Mass Spectrometry (PTR-MS) (n=54). Moreover, the intensity of two aroma descriptors was evaluated using a dynamic time-intensity sensory evaluation (n=26).

Ex vivo experiments showed that oral mucosa reduced the release of all aroma compounds assayed and that cells and saliva metabolized aroma compounds in a compound-dependent manner (p<0.05). Interestingly, in vivo experiments confirmed that the compounds metabolized ex vivo disappeared quicker in the breath than the compounds not metabolized by cells and saliva (p<0.05). The same trend was observed in the sensory experiments, which confirmed the sensory meaning of these findings. Overall, results from this work suggest that aroma persistence is driven by both, biological and physicochemical mechanisms.

Monday
Discussion
10:05am - 10:25am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry

Monday
Intermission
10:25am - 10:40am USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry

Monday
Perception of flavor is a dynamic process during which the concentration of aroma molecules at the olfactory epithelium varies with time as they are released progressively from the food in the mouth during consumption. However, how the various components combine to produce a sensory impression is still not completely understood. Real-time mass spectrometry (MS) techniques that measure aroma compounds directly in the nose (nosespace) aim at obtaining data patterns that are supposed to reflect the way aromas are released in real time during food consumption. These patterns are supposed to be representative of the retronasal stimuli perception. Real-time sensory methods, such as time-intensity, or the more recent Temporal Dominance of Sensations (TDS) and Temporal Check All That Apply (TCATA) procedures, are used to account for the dynamic and time-related aspects of flavor perception. Combined together, preferably simultaneously in a fully real-time in vivo approach, both chemical and sensory methods should provide fundamental results to understand the link between aroma release and aroma perception better.
The present lecture will present an overview of the advances made for combining real-time nosespace analysis with simultaneous temporal sensory evaluation. In order to analyse conjointly the two sets of data, a statistical procedure will be presented and discussed. These advancements will be illustrated and discussed through the study of the flavor of three dark chocolates differing in sensory properties, analyzed by a panel of 16 assessors in nosespace with a PTR-ToF-MS instrument and simultaneous TDS or TCATA sensory evaluation. Results obtained with TDS and TCATA will be compared.
Nosespace with PTR-MS and simultaneous TCATA evaluation of dark chocolate

Nosespace with PTR-MS and simultaneous TCATA evaluation of dark chocolate


Monday
Many of the regularly consumed foods are composite foods, which consist of multiple components differing in composition and properties, i.e. toppings and condiments combined with vegetables or potatoes, sauces and spreads combined with bread or crackers. The characteristics of each component can differ considerably and may influence physically and chemically flavour release and sensory perceptions of the other components.

Characterizing composite foods has recently gained interest not only due to their increased sensory complexity, but also because composite foods are more representative of the natural consumption context and may be a way to address eating behaviours issues.

An optimal experimental approach for the investigation of the flavour evolution of composite food during oral processing is the combining of dynamic sensory methods with simultaneous nose-space analysis by high sensitivity direct injection mass spectrometry.

In this work we discuss two case studies related to important food combinations: i) the influence of different carriers on the flavour release and perception of extra virgin olive oil (EVO); ii) investigation of the effect of food structure and composition on aroma release and sensory perception of chocolate-hazelnut spreads. In both cases Temporal-Check-All-That-Apply (TCATA) was coupled with in vivo nose space analysis using a commercial PTR-ToF-MS (Proton Transfer Reaction Time-of-Flight Mass Spectrometer, Ionicon Analytik, Innsbruck, Austria).

In the first case study 2 different EVO oils were tested alone and with 2 carriers (bread and chickpea) by 10 panellists wearing a glass nosepiece connected to the PTR–ToF–MS with a ( PEEK tube (50 cm at room temperature and then heated at 110°C).
In the second case study three different formulation of chocolate-hazelnut spread varying in fat and sugar content (high fat/high sugar; high fat/low sugar; low fat/high sugar) together with 2 carriers (bread and wafer) were evaluated by 8 subjects. The spreads were spiked with 5 aroma compounds (Benzaldehyde, Filbertone, δ-decalactone, Isovaleraldehyde, 2-methylpyrazine). For this study a heatable nosepiece system (Ionicon Analytik, Innsbruck, Austria) was used for nosespace analysis.
In both case studies the effects of different products, addition of carriers and interindividual differences were observed. We are currently working on the investigation of the relationship between volatile release during nosespace analysis and sensory response.

Monday
It is known that factors affecting flavor release during food consumption comprise a complex interplay between biology and eating behaviors. However, evidence supporting the effect of both components on representative sample sizes using an ecologically valid method are still lacking.
Mounting evidence suggests that real time MS in–vivo monitoring the volatile organic compounds exhaled from the nose during food consumption, also called nose-space analysis, still remains the most direct way to non-invasively investigate the dynamics of flavor release and, therefore, it ought to be considered as the gold standard method when such studies are thought to be performed.
Hence, this contribution aims to get insights on the inter-individual variability on flavor release of a representative healthy population, monitored in real time, by taking into account both some biological (i.e. gender, age, BMI) and behavioral variables. To address this later issue, Food Neophobia, a widely studied eating behaviour trait that measures the reluctance to eat what is unfamiliar, and trait anxiety were chosen.
Eighty-three subjects (57.8 % female; aged 22 to 68 yo) consumed, according to a fixed chewing procedure supported by a video tool, a strawberry jelly candy chosen as reference food to study aroma release. Simultaneously, nose-space analysis with Selected-Ion Flow-Tube Mass Spectrometry (SIFT-MS) was carried out by monitoring in real time the release of 7 key aroma compounds (5 esters, 2 alcohols).
Flavour profiles information based on parameters commonly used to analyze time-intensity (T-I) curves (i.e. AUC, Imax, Imean, TImax, Tend , Slope) revealed a slightly negative effect of age and BMI on flavor release. No gender effect was observed.
Moreover, individuals with lower Food Neophobia and trait anxiety tendencies showed a higher extent of flavor release, probably due to a longer oral processing and lower anxiety-related physiological responses (such as breathing rate).
These results confirm that real time MS nose space monitoring is an efficient tool to unravel the dynamics of flavor release. As a final remark, we advocate the usage of both representative sample sizes and to consider its multidimensional nature once mechanisms underlying flavor release are under investigation.

Monday
Proton Transfer Reaction Mass Spectrometry has been described has particularly suited to provide “in vivo” on-line flavor monitoring during food consumption. In the last years, the technique has been applied to
different food matrixes. Due to analysis rapidity and high sensitivity, the technique has become a
reference tool for the investigation of the complex phenomena related to flavor perception. In this work we describe a PTR-MS nose-space approach coupled to different dynamic sensory methods to
investigate the influence of product properties and participants characteristics on in-vivo aroma release
and perception.
In the first part, the influence of food properties on in-vivo aroma release and perception will be explored. Case studies on chewing gum formulation, composite foods and on raw and cooked cabbage will be
presented. For the chewing gum the effect of gum base and aroma concentration on aroma and sweeteners release and flavor perception was tested. The approach was also tested on commercial samples to evaluate samples differences. In the composite food study mayonnaises varying in fat content (high/low)
and viscosity (high/low) were consumed alone and in combination with carriers differing in moisture
absorption capacity (bread, potato) and hardness (hard/soft). The same approach was applied to evaluate
the effect of both condiment and carrier properties on in vivo aroma release and lemon perception through
time intensity sensory test. In the last study another kind of sensory test, Temporal Dominance of
Sensation was applied to characterize flavor differences of raw and cooked cabbage samples.
In the second set of studies, the effect of physiological parameters (oral cavity volume, salivary flow and
papillary count), gender and ethnicity in flavor perception and aroma release was investigated by using
chewing gum and cabbage as food product.
Overall, the results of the studies suggest a multimodal effect of aroma release on both flavor and sweetness intensity. Individual differences due to physiological, biochemical and physiocochemical phenomena may have a relevant effect in aroma perception and thus in sensory flavor perception. Real time direct injection mass spectrometric analysis coupled with dynamic sensory methods, is confirmed as a powerful tool to investigate flavor perception mechanisms and highlight physiological and cultural biases.

Monday
Discussion
11:40am - 12:00pm USA / Canada - Pacific - April 5, 2021
Track: [AGFD] Division of Agricultural and Food Chemistry

Awards Ceremony: Gin New Investigator and Derek Horton Award:  
09:00am - 12:00pm USA / Canada - Pacific - April 5, 2021
Peter Andreana, Organizer, Presider; Alexei Demchenko, Presider
Track: [CARB] Division of Carbohydrate Chemistry
Division/Committee: [CARB] Division of Carbohydrate Chemistry

Gin New Investigator and Derek Horton Award

Monday
Introductory Remarks
09:00am - 09:02am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Decoding the Glycome
09:02am - 09:31am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Glycans offer cells a rich coding space, enabling the encoding of cellular information, such as cell state (Signal). However, their position at the outer edge of cells makes them a target for pathogens, requiring variation to be added to the code to avoid being targeted (Noise). This leads to a system in which the sugar code (i.e. the glycan motifs controlling function) is hidden within the noisy milleu of larger heterogenous glycan structures. This talk focuses on use of high-throughput analytical methods, including our lectin microarray technology and newly developed miRNA-proxy approach, in tandem with data integration, to decode structure-function relationships in the glycome. Our work is identifying glycan drivers of disease, focusing on clinical samples and relevant systems. The talk will discuss our latest work in this area.

Monday
Discussion
09:31am - 09:36am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Bacterial peptidoglycan fragments to investigate innate immune activation
09:36am - 10:05am USA / Canada - Pacific - April 5, 2021
Catherine Grimes, Presenter
Track: [CARB] Division of Carbohydrate Chemistry
The human body is covered with bacteria. It has been estimated that for every human cell there are ten bacterial cells living in or on the human body. The bacteria that occupy the human body, which do not cause harm are called commensal bacteria. These bacteria normally provide essential functions for the human body, for example they aid in digestion. However, chronic inflammatory diseases such as asthma, rheumatoid arthritis, and Crohn’s disease are thought to arise from an inappropriate response to commensal bacteria. Chronic inflammation has also been shown to lead to a variety of types of cancers including gastric, colon, and lung. The immune system’s interaction with bacteria plays a pivotal role in these diseases and in order to develop novel therapies for these diseases, better tools are needed to dissect how the immune system interacts with the microbiome.
The field of bacterial activation of the innate immune system is limited to a few select synthetic tools derived from bacterial peptidoglycan. The bacteria are believed to communicate to the human cell through the use of specific carbohydrate polymers. The synthesis of these polymers is extremely demanding and thus the probes are scarce. My research laboratory has focused on developing a combination of chemical and enzymatic synthesis to prepare bacterial cell wall fragments from a number of different types of bacteria. These fragments are then used to investigate how different strains of bacteria initiate an immune response. Here we will discuss our progress in using these tools to probe innate immune recognition pathways.

Monday
Discussion
10:05am - 10:10am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Intermission
10:10am - 10:15am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Introductory Remarks
10:15am - 10:17am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
The development of small molecular weight glycomimetic drugs has been steadily increasing during the last 20 years. These molecules target various proteins by acting as high-affinity decoys which mimic large cell-surface carbohydrates involved in a variety of key biological processes. Many of these carbohydrate-protein interactions (CPIs) are key molecular recognition events that are implicated in a diverse array of diseases including inflammation, cancer, and infectious diseases. The latest and most intensive research in this area has been focused on the rational design of glycomimetic bacterial lectin antagonists. Examples include mannoside and galactoside ligands targeting the FimH, PapG and FmlH lectins of chaperone usher pathway pili of uropathogenic Escherichia coli, important in the pathogenesis of urinary tract infections (UTIs) and Crohn's Disease. Others include glycoside antagonists of LecA and LecB in Pseudomonas aeruginosa a major causative agent of severe tissue wounds and burns as well as pneumonia, especially in cystic fibrosis patients. We have used X-ray crystallography to design tight-binding ligands of FimH and FmlH which are effective at blocking bacterial binding and clearing UTIs in vivo. A common feature of the most potent analogs is a substituted biphenyl or biaryl aglycone. We discovered that a para-biaryl group is preferred in mannoside FimH antagonists while and ortho-biaryl group is optimal for the galactoside FmlH ligands. We have also elucidated through molecular docking and initial data that a meta-biaryl aglycone is ideal for other lectins. This data, taken with the numerous other reported glycomimetics that often contain a biphenyl, biaryl or one-atom spaced biaryl (e.g. ether) strongly suggest that these aglycone two-ring systems are closely mimicking the electronic and steric properties of a disaccharide. In most cases there is a well-defined one-sugar binding pocket thus rationalizing the requirement for at least one sugar (α-mannose for FimH, β-galactose for FmlH and LecA, α-galactose for PapG and fucose for LecB). The shape of the extended binding surface surrounding the sugar pocket (e.g. tyrosine gate in FimH), which is determined by its carbohydrate receptor binding epitope, can be effectively mimicked with a monosaccharide bearing an appropriately substituted biaryl ring aglycone. This strategy will be useful in expediting the development of future glycomimetic lectin antagonists as novel anti-infective agents.
Monday
Discussion
10:46am - 10:51am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
How to pay for the costs of desolvation accompanying carbohydrate-lectin interactions?
10:51am - 11:20am USA / Canada - Pacific - April 5, 2021
Beat Ernst, Presenter
Track: [CARB] Division of Carbohydrate Chemistry
Carbohydrate-lectin interactions are accompanied by high desolvation costs, which is a major reason for their low affinity. The desolvation of a single hydroxy group is associated with an energy penalty of approx. 26 kJ/mol, a value higher than the energy gain related to a H-bond (at maximum 20 kJ/mol).[1] For polyhydroxylated ligands, desolvation effects therefore add up to substantial energy penalties.

To compensate for the desolvation penalty, carbohydrate/lectin interactions can take advantage of the following effects:
- Pre-organization of the bioactive conformation of lectin antagonists can substantially reduce entropy costs.[2,3]
- The spatial proximity of both the non-binding surface of the lectin and the oligosaccharide ligand force partial desolvation of solvate layers and thus improve the entropy term.[4]
- The improvement of affinity by multivalent epitope presentation is demonstrated on the example of a monoclonal IgM autoantibody recognizing the HNK-1 (human natural killer-1) epitope.[5]
- Shaping of the local dielectric constant by conformational adaption can improve binding enthalpy, as demonstrated on the example of the bacterial adhesin FimH.[6]

The various factors will be presented on the basis of specific in-house examples.

Monday
Discussion
11:20am - 11:25am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Glycomimetic drugs: From rational design to clinical trials
11:25am - 11:54am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry
All cell surfaces are coated with carbohydrates that contain structural information used in recognition processes. Carbohydrates however lack drug-like properties. Our approach is to rationally design small molecule mimics of functional carbohydrates using empirical techniques. GMI-1070 (rivipansel) was designed to inhibit E, P, and L-selectins by incorporating a mimic of sialyl Lex together with that of the tri-sulfated domain of PSGL-1. The selectins are known to play a role in the adhesion of cells in vaso-occlusive crisis (VOC) in sickle cell disease patients which causes acute morbidity, pain, and early mortality. The RESET trial (NCT02187003) was a phase 3 study of rivipansel for VOC. Although statistical improvements in outcomes were not shown for patients admitted at all time points after the start of VOC, post hoc analysis demonstrated that treatment within 26.4 hr results in clinically meaningful benefit for endpoints. To address this need for early treatment, a potent E-selectin antagonist for patient delivery outside of a hospital setting was designed. GMI-1687 binds E-selectin with a KD of 2.3 nM and is subcutaneously bioavailable. In animal models of VOC, GMI-1687 blocked occlusion and normalized blood flow at 0.04 mg/kg BID. The second compound in clinical trials is GMI-1271 (uproleselan), a highly specific antagonist of E-selectin. The bioactive conformation of stacking the fucose under the galactose was stabilized by an ethyl group off the cyclohexyl. Replacements for the sialic acid and correct orientation of its carboxyl group increased activity. Serum half-life was improved by attaching polyethylene glycol which reduces non-specific binding to serum proteins and increases accessibility to E-selectin. The microvasculature in the bone marrow expresses low levels of E-selectin which induces chemoresistance that is broken by uproleselan. Patients were treated with uproleselan in combination with chemotherapy (MEC). Based on positive phase 2 data, the FDA granted uproleselan “Breakthrough Therapy Designation”. Our third clinical candidate drug (GMI-1359) was designed to inhibit both E-selectin and the chemokine receptor, CXCR4. E-selectin draws tumor cells into the bone marrow and CXCR4 stabilizes them. Animal models of bone metastasis treated with GMI-1359 and chemotherapy show reduction of tumor volume and significant improvement in survival. GMI-1359 is now being studied in breast cancer patients at Duke University.
Monday
Discussion
11:54am - 11:59am USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry

Monday
Concluding Remarks
11:59am - 12:00pm USA / Canada - Pacific - April 5, 2021
Track: [CARB] Division of Carbohydrate Chemistry