Description:

Mark Styczinski of Georgia Tech.

Host: Keith Tyo

Short bio:
Mark Styczynski is an Associate Professor in the School of Chemical & Biomolecular Engineering at the Georgia Institute of Technology. A major emphasis of his research is the use of synthetic biology to develop low-cost, minimal-equipment diagnostics for the developing world. He also uses metabolomics to study multiple model systems and to drive development of computational modeling techniques to improve metabolic engineering. He has received NSF’s CAREER award, DARPA’s Young Faculty Award, and NIH’s MIRA Young Investigator award. He is on the editorial board for Mathematical Biosciences, and is the founding president of the Metabolomics Association of North America.

Title:
Applying synthetic biology for minimal-equipment, point-of-care diagnostics

Abstract:
Millions of people die every year from deficiencies in micronutrients (vitamins and minerals), mostly in the developing world. The cost of providing micronutrient supplementation precludes global-scale interventions and requires more targeted allocation of limited aid resources. However, existing methods to measure micronutrient status are so expensive and logistically difficult that insufficient clinical data is available to know which regions most need help. A low-cost way to measure micronutrient status of patient populations in low-resource environments could let agencies better allocate their resources, impacting millions of lives. This is a challenging task, though, as detection must also be semi-quantitative: all samples have micronutrients, the question is whether the levels are sufficient. Semi-quantitative measurement modalities typically require expensive analytical instruments that are infeasible in these environments.

Our group has developed minimal-equipment biosensors capable of sensing zinc (a critical micronutrient) and producing visible colors indicating the zinc concentration. We have developed a whole-cell biosensor in E. coli, and have shown that the diagnostic thresholds between colors can be tuned using synthetic biology and metabolic engineering. We have developed genetic circuits that allow these cells to rapidly produce color on a timescale consistent with the demands of micronutrient surveillance campaigns in the field, and we have shown that these sensor cells are active in high concentrations of untreated human serum. We have also recently developed an analogous cell-free TX-TL assay that produces semi-quantitative visible readouts in an hour, with built-in, sample matrix-specific quantitative standards.

We aim to use this framework for portable, low-cost, low-resource measurement to eventually develop a suite of micronutrient sensors (whether whole-cell or cell-free) to help address micronutrient deficiency on a global scale.

Description:

Charles Sing of UIUC.

Host: Mitchell Wang

Title
Tuning Polyelectrolyte Interactions via Charged Monomer Sequence

Abstract
Charged polymers known as polyelectrolytes have been studied for decades, however understanding their physical properties remains a persistent challenge for polymer scientists. This difficulty stems from the intricate interplay between length scales spanning as much as 3-4 orders of magnitude, which has stymied our understanding of a truly important class of polymers; polyelectrolytes are widely used in applications ranging from food additives to paints, and most biopolymers (proteins, DNA, polysaccharides) are also polyelectrolytes.

However, the complexity of charged polymers can be harnessed for molecular-level materials design. To demonstrate this, we study a class of polyelectrolyte materials known as complex coacervates. Complex coacervates are aqueous solutions composed of oppositely-charged polyelectrolytes and salt that undergo an associative phase separation process. We use simulation and theory, along with close experimental collaboration, to demonstrate that coacervates are highly sensitive to the precise placement of molecular charge. We elucidate the key molecular features that play a large role in coacervate thermodynamics. Building upon these insights, we demonstrate how coacervate phase behavior can be strongly tuned via specific charge sequences. We will show how the physical principles governing the thermodynamics of sequence-defined polyelectrolytes provides the foundation to study coacervate-driven assembly on length scales ranging from monomer-level structure to block copolymer nanophase separation.

Bio
Charles Sing is an Assistant Professor of Chemical and Biomolecular Engineering at the University of Illinois at Urbana-Champaign. He received his BS and MS in polymer science from Case Western Reserve University in 2008, and his PhD in materials science from MIT in 2012. Prior to starting at Illinois in 2014, Charles was a postdoctoral fellow at Northwestern University. His research interests are broadly in the area of computational and theoretical polymer physics; current projects focus on molecular and sequence properties of polyelectrolyte solutions, out-of-equilibrium rheology of semidilute polymers, and polymers with nonlinear architectures. He was recognized as one of Forbes' '30 Under 30 in Science' in 2015, and the recipient of an NSF CAREER Award in 2017.

Description:

Mahdi Abu-Omar of UCSB.

Host: Eric Masanet

Title:
Chemical Synthons and Smart Materials from Lignin

Abstract:
Transition metal catalysts have been an integral part of the success story of the petrochemical industry in the past century. For this century and the future, we must advance developments in renewable energy and the utilization of sustainable resources to make chemicals and materials. Approximately 1.4 billion tons of lignocellulosic biomass is an annually renewable source of energy and chemicals in the U.S. alone. The major components of biomass are cellulose, xylan, and lignin- all polymeric and contain high percentage of oxygen. Current biomass processing underutilizes lignin. We have developed selective reaction chemistries that convert lignin selectively into phenolic molecules/synthons. We have coined this process chemistry CDL for Catalytic Depolymerization of Lignin. Spectroscopic data coupled with mechanistic investigations revealed the roles of solvent and catalyst in this unique reactive-separation, which provides selective molecules from lignin. Renewable triphenol motifs (TPs) have been synthesized and converted to polymers with advanced thermo-mechanical properties that rival those from petroleum. A fully biobased epoxy thermoset has been prepared by esterification of lignin-derived TP with vegetable oil to yield materials with tunable mechanical properties and glass transition temperature. The implication and use of lignin synthons to make renewable, recyclable, and self-healing thermoset polymers will be discussed.

Bio:
Mahdi Abu-Omar is the Suzanne and Duncan Mellichamp Professor of Green Chemistry at the University of California, Santa Barbara (UCSB), and the associate director of the Center for Catalytic Conversion of Biomass to Biofuels (C3Bio), an Energy Frontiers Research Center funded by the US Department of Energy. Mahdi is the Founder and President of Spero Energy, Inc., a chemistry technology company specializing in commercial production of renewable and natural molecules from biomass. He has authored more than 160 original research articles in peer-reviewed scientific journals. His research interest is in the areas of sustainability and green chemistry through the development and understanding of inorganic catalysts. Mahdi is a Fellow of the American Association for Advancement of Science (AAAS) since 2012 and was a Senior Fulbright Fellow (2008). He chaired the Gordon Research Conference on Inorganic Reaction Mechanisms in 2013. Dr. Abu-Omar completed his Ph.D. from Iowa State University and postdoc from Caltech.

Description:

Sol Ahn, Notestein/Farha Groups:

Title
Solid Acid Catalyzed C-C Bond Isomerization and Disproportionation over Tungstated NU-1000

Abstract
Acid-catalyzed skeletal C-C bond isomerizations are important reactions for the petrochemical industries. Hydrocarbons such as hexane and xylene are crucial reactants in the production of fuels and basic petrochemicals, and these have been model reactions that provide structural information on solid acid catalysts. Among those, o-xylene isomerization/disproportionation is a probe reaction for strong Brønsted acid catalysis, and it is also sensitive to the local acid site density and pore structure.

I will discuss the use of phosphotungstic acid (PTA) encapsulated within a Zr-based metal–organic framework (MOF), NU-1000, as a catalyst for o-xylene isomerization and disproportionation. Extended X-ray absorption fine structure (EXAFS), 31P NMR, N2 physisorption, and powder x-ray diffraction (PXRD) show that the catalyst is stable after the reaction condition. Initial rates over the NU-1000-supported catalyst were comparable to a control WOx-ZrO2, however the NU-1000 supported catalyst was unusually active toward the transmethylation pathway that requires two adjacent active sites in a confined pore, as created when PTA is confined in NU-1000. This work shows the promise of metal–organic framework topologies in giving access to unique activity, even for aggressive reactions such as hydrocarbon isomerization.

Anyang Peng, Kung Group:

Title
Low temperature selective oxidation of ethylbenzene by catalyzed co-oxidation using Co-ZSM-5 and solubilized Au clusters catalysts: extend the reach of heterogeneous catalysis

Abstract
Selective oxidation of hydrocarbon using of the ubiquitous molecular O2 as the terminal oxidant is economically attractive but challenging due to the kinetic constraint imposed by the triplet ground state of dioxygen and the inherently inertness of the C-H bonds. One such oxygen driven strategy is co-oxidizing two or more substrates through one-pot cascade reactions in which a kinetically or thermodynamically limited partial oxidation reaction is facilitated by another partial oxidation reaction occurring simultaneously, with the help of multiple heterogeneous catalysts or multi-functional heterogeneous catalysts.
Throughout its history, heterogeneous catalysis process has been considered to occur by kinetic coupling of elementary steps including adsorption, surface reactions and desorption; nevertheless, this process is often accompanied by formation of reactive intermediates, which can diffuse through the surrounding fluid media and lead to cascade reactions that are beyond the reach of heterogeneous catalysis. Herein we report the Au & Co co-catalyzed co-oxidation of cyclooctene (COE) and ethylbenzene (EB) with molecular O2 to form the useful products of cyclooctene epoxide and acetophenone under mild temperature and ambient pressure. To the best of our knowledge, this is the first example of a unique cascade reaction, in which a sequential reaction was catalyzed by the active intermediate generated from a previous reaction. A better understanding of properties of
energetic reactive intermediates and their contributions to multi-reaction networks would ultimately lead to more efficient use of atoms and energy in chemical transformations

Description:

Vivek Sharma of UIC.

Host: Wes Burghardt

Title:
Stretched Polymer Physics, Pinch-off Dynamics, Rheology and Printability of Polymeric Complex Fluids

Abstract:
Liquid transfer and drop formation/deposition processes associated with printing, spraying, atomization and coating flows involve complex free-surface flows including the formation of columnar necks that undergo spontaneous capillary-driven instability, thinning and pinch-off. For simple (Newtonian and inelastic) fluids, a complex interplay of capillary, inertial and viscous stresses determines the nonlinear dynamics underlying finite-time singularity as well as self- similar capillary thinning and pinch-off dynamics. In rheologically complex fluids, extra elastic stresses as well as non-Newtonian shear and extensional viscosities dramatically alter the pinch- off dynamics. Stream-wise velocity gradients that arise within the thinning columnar neck create an extensional flow field, and many complex fluids exhibit a much larger resistance to elongational flows than Newtonian fluids with similar shear viscosity. Characterization of the response to both shear and extensional flows that influence dispensing and liquid transfer applications requires bespoke instrumentation not available, or easily replicated, in most laboratories. Here we show that dripping-onto-substrate (DoS) rheometry protocols that involve visualization and analysis of capillary-driven thinning and pinch-off dynamics of a columnar neck formed between a nozzle and a sessile drop can be used for measuring extensional viscosity and extensional relaxation time of polymeric complex fluids. We show that the DoS rheometry protocols we have developed enable the characterization of low viscosity printing inks and polymer solutions that are beyond the measurable range of commercially-available capillary break-up extensional rheometer (CaBER). We find that the extensional relaxation times of dilute and semi-dilute, unentangled polymers in good solvent exhibit much stronger concentration dependence than observed in shear rheology response or anticipated by blob models developed for relaxation of weakly perturbed chains in a good solvent. We investigate the role of charge by contrasting the pinch-off dynamics and the rheological response of weak and strong polyelectrolytes and characterizing the influence of the electrolyte concentration. We elucidate the influence of chemical structure on stretched polymer physics by contrasting the behavior of aqueous solutions of flexible polyethylene oxide (PEO) with solutions of semi-flexible hydroxyethyl cellulose (HEC). We show that flexibility, extensibility and charge dramatically influence the extensional rheology response and the macromolecular relaxation dynamics. Finally, we elucidate how macromolecular stretching and orientation in response to strong extensional flows modifies the excluded volume and hydrodynamic interactions, affecting the terminal extensional viscosity response as well as polymer relaxation dynamics, and consequently, determine the filament lifespan, the processing timescale, and processability for printing, coating, dispensing, and spraying applications.

Biography:
Dr. Vivek Sharma is an Assistant Professor of Chemical Engineering at the University of Illinois Chicago. Before joining UIC in November 2012, he worked as a post-doctoral research associate in Mechanical Engineering at Massachusetts Institute of Technology. He received his Ph. D. (Polymers/MSE, 2008) and M. S. (Chemical Engineering, 2006) from Georgia Tech., an M. S. (Polymer Science, 2003) from the University of Akron, and a bachelor's degree from IIT Delhi. Dr. Sharma's research interests broadly lie in optics, dynamics, elasticity, and self-assembly (ODES) of complex fluids and soft materials. At UIC, Dr. Sharma's Soft Matter ODES-lab combines experiments and theory to pursue the understanding of, and control over interfacial and nonlinear flows, focused on the interplay of (a) viscoelasticity and capillarity for printing applications and extensional rheometry, and (b) interfacial thermodynamics and hydrodynamics in fizzics (the science of bubbles, drops, thin films, jets, fibers, emulsions and foams). Dr. Sharma was selected as the Distinguished Young Rheologist by TA Instruments in 2015, and won the 2017 College of Engineering Teaching Award at UIC.