Spring 2018

Departmental Seminars

 

January 8, 2018
10:30 AM
Room 1011, EB1
Dr. Victor Ugaz
Texas A&M University

I will describe recent work in our research group aimed at harnessing fundamental transport phenomena at the microscale in ways that can help enable the development of rapid portable bioanalysis systems. First, I will introduce a novel method to actuate DNA replication via the polymerase chain reaction (PCR) by exploiting thermally driven natural convection. This implementation offers advantages including an inherently simple design (similar to a lava lamp) and minimal electrical power consumption (critical for portable applications). We have probed the 3-D velocity and temperature distributions inside microscale convective reactors, and unexpectedly discovered a subset of complex flow trajectories where extremely rapid DNA replication rates are achievable due to the onset of chaotic advection. These discoveries have enabled us to construct an ultra-portable and inexpensive bioanalysis platform for rapid nucleic acid-based diagnostics that can be deployed using consumer-class quadcopter drones.

These surprisingly complex 3D convective flows are also able to function as highly efficient conveyors capable of continually shuttling molecular species from the bulk fluid to targeted locations on the solid boundaries. Our results demonstrate that chaotic thermal convection is capable of delivering an order of magnitude acceleration in surface reaction kinetics under conditions naturally found in subsea hydrothermal microenvironments, potentially shedding light on a key process associated with the origin of life on Earth and elsewhere.

Finally, I will show how specific biochemical interactions between an enzyme and a biodegradable substrate can be harnessed to execute precise flow-actuated micromachining. This novel approach makes it possible to construct a microfluidic-based filtration device capable of performing simultaneous size-based isolation and enrichment of cells from whole blood. The underlying inertial flow phenomena can be tuned to achieve efficient separations at high flow rates, making this design ideally suited for high-throughput processing of large sample volumes.

January 29, 2018
10:30 AM
Room 1011, EB1
Ollis Lecture
Dr. Greg Russotti
Celgene Cellular Therapeutics

Despite approvals of such cell therapies as artificial skin substitutes as far back as the 1990’s, the cell therapy field has yet to experience a “blockbuster drug”.  The complexities of developing cell therapies, including their multi-faceted mechanisms of action, their labor-intensive and expensive manufacturing processes, and, in some cases, poorly understood clinical indications, offer many obstacles to the successful commercialization of these modalities. Recently, the field has offered great promise with the emergence of adoptive T cell therapies, such as CAR-T cells (chimeric antigen receptor T cells) and TILs (tumor infiltrating lymphocytes). Furthermore, there are a multitude of ongoing MSC (mesenchymal stromal cell) trials entering Phase II and III in diseases such as stroke, congestive heart failure, GVHD, and Crohn’s disease.

In order for cell therapies to be successful, several process development and manufacturing challenges will need to be addressed. Many of these are unique to cell therapies and have not been encountered when developing small molecules, recombinant proteins such as monoclonal antibodies, or even other non-cellular complex biologics. Some of these novel challenges will be discussed, including:

  • Potency assays and specifications: How to choose appropriate potency assay(s) with relevant specifications when a cellular therapy may have multiple potential mechanisms of action and may behave differently in different patients? This is in contrast to most drugs that are being developed with a clear target and proposed mechanism of action.
  • Control of donor variability: How and when to bridge from one donor source to another for allogeneic products, for which a single donor may yield very large numbers of doses but not last for the lifetime of the product?
  • Time-limited steps impeding batch scale-up: How to design large-scale filling processes for cryo-preserved products, considering the limited time that living cells can be exposed to cryo-protectants, such as DMSO, before freezing?
  • Scaling out patient-specific or autologous products: How to improve COGs and reduce labor when each patient preparation is its own batch?

February 5, 2018
10:30 AM
Room 1011, EB1
Gubbins Lecture
Dr. Sharon Glotzer
University of Michigan

Entropy, information, and order are important concepts in many fields, relevant for materials to machines, for biology to econophysics. Entropy is typically associated with disorder; yet, the counterintuitive notion that a thermodynamic system of hard particles might – due solely to entropy – spontaneously assemble from a fluid phase into an ordered crystal was first predicted in the mid-20th century. First predicted for rods, and then spheres, the ordering of colloids by entropy maximization upon crowding is now well established. In recent years, surprising discoveries of ordered entropic colloidal crystals of extraordinary structural complexity have been predicted by computer simulation and observed in the laboratory. These findings, which we present in this talk, demonstrate that entropy alone can produce order and complexity beyond that previously imagined, and that, in situations where other interactions are also present, the role of entropy in producing order may be underestimated. We quantify shape entropy in the self-assembly of colloidal systems, from nanoparticles to proteins, discuss the notion of the entropic bond in the context of traditional chemical bonds, and show how the entropic bond may be precisely engineered despite its statistical, emergent nature.

February 6, 2018
3:00 PM
Room 135, BTEC
Gubbins Lecture
Dr. Sharon Glotzer
University of Michigan

From the Stone Age to the Information (Silicon) Age, the materials available to humankind define the world in which we live. The materials of tomorrow will be rich in information content, be programmable, and be responsive to stimuli, just as biological matter is, and they will be designed and engineered on demand, where and when they are needed, with precision and personalization. Theory, modeling and simulation play a critical role in the inverse design of nanoparticle and colloidal materials in particular by enabling the selection – from a nearly infinite number of possibilities – of building blocks optimized for structure and properties. In this talk, we present a new thermodynamic approach to the inverse design of colloidal matter we call Digital Alchemy, and demonstrate its use in obtaining colloidal crystals with arbitrary complexity, engineered phase transitions, and target photonic properties.

February 12, 2018
10:30 AM
Room 1011, EB1
Dr. Tim Long
Virginia Tech

3D printing, or additive manufacturing (AM), provides diverse opportunities to create previously unattainable geometric objects through a layer-by-layer fabrication process. Novel macromolecular structures and synthetic methods in synergy with unique methods of printing demonstrated micron-scale resolution 3D part generation tunable to emerging technologies. Microstereolithography of poly(amic diethyl acrylate ester)s yielded soft 3D organogels. Upon thermal imidization, this organogel transformed into a 3D structured thermoplastic polyimide, which is unachievable in conventional manufacturing. Furthermore, the backbone of the polyimide exhibited versatility through processing of both rigid-rod, insoluble thermoplastics and amorphous, melt-processable thermoplastics. These unprecedented polyimide objects offer immediate impact in aerospace, medical, architectural, and automotive applications. The versatility of 3D printing also provides micron-scale resolution of poly(ether ester) ionomers through low temperature material extrusion for the inclusion of biologics and therapeutics. Typical melt polymerization of poly(ether ester) ionomers from poly(ethylene glycol) and sulfonated isophthalate provided water-soluble polymers capable of complete ion exchange. The incorporation of divalent counterions such as calcium, magnesium, and zinc provided an increase in melt viscosity necessary for low temperature material extrusion 3D printing. Filament of poly(ether ester) ionomers with a calcium counterion revealed successful, flexible filament for subsequent processing. 3D printed structures maintain shape upon printing without flow from the nozzle, successfully demonstrating material extrusion from filament for the first time below 80 °C. By tuning polymer structure, printing type, and printing parameters, diverse structures for vastly different applications ranging from drug delivery and controlled release fertilizers to satellites and aerospace. This lecture will highlight structure-property-processing relationships for the design of advanced materials for several additive manufacturing platforms. The synergy of chemistry and mechanical engineering will be demonstrated in each case study.

February 19, 2018
10:30 AM
Room 1011, EB1
Dr. James Swan
Massachusetts Institute of Technology

Colloidal gels are formed during arrested phase separation. Sub-micron, mutually attractive particles aggregate to form a system-spanning network with high interfacial area, far from equilibrium. Such networks are useful as soft composites composed of a virtually limitless variety of materials for the particulate and fluid phases.  They find applications in food as soft solids like yogurt and cheese, medicine as scaffolds for tissue engineering, and energy as flowable electrodes in flow battery devices.  Engineering the growth and response of gels to large deformations is a central effort in all these applications.  Models for microstructural evolution during colloidal gelation have often struggled to match experimental results with long standing questions regarding the role of hydrodynamic interactions. In the present work, we demonstrate simulations of gelation with and without hydrodynamic interactions between the suspended particles. The disparities between these simulations are striking and mirror the experimental-theoretical mismatch in the literature. The hydrodynamic simulations agree with experimental observations, however. We explore a simple model of the competing transport processes in gelation that anticipates these disparities, and conclude that hydrodynamic forces are essential.  We show through detailed simulations and analytical theory how competing transport processes are affected by hydrodynamic interactions between colloids and extend the simulations beyond the quasi-static limit to study the breakdown of gels under flow.  Our simple model is capable of reproducing the results from a variety of flow scattering experiments, and suggest a pathway to understanding the co-evolution of structure and stress in flowing, attractive dispersions.

February 26, 2018
10:30 AM
Room 1011, EB1
Dr. Nathalie Lavoine
North Carolina State University

Nanocellulose in the form of Cellulose Nanocrystals (CNC) and Cellulose Nanofibers (CNF) has been the focus of a significant research interest during the last two decades. Nanocellulose is an abundant and renewable nanomaterial that combines a low density, high strength and flexibility with chemical inertness and versatility. Nanocellulose-based materials are nowadays developed for a wide range of applications including composites, (smart) packaging, flexible optoelectronics, scaffolds for tissue regeneration or drug delivery.

Since 2010, my research activities are focusing on the use of CNF for the elaboration of functional materials. During this seminar, I will then present how to use CNF for developing (i) controlled release packaging, (ii) composites with enhanced thermal stability, and (iii) thermally insulating foams.

Despite significant research activities on CNF, there is still lack of multi-scale understanding of the CNF entanglement, which is key for developing tailored functional materials.

This is the main challenge that I am motivated to address at NC State University. I will thus give you some insight into different approaches that I am considering as future research topics and collaborations.

March 12, 2018
10:30 AM
Room 1011, EB1
Dr. Yan Yu
Indiana University

The immune system functions on the basis of intricately organized chemical reactions and physical forces. Examples range from the engulfment of invading bacteria that relies on a fine balance of competing mechanical forces, to the activation of Tlymphocytes that requires collective interactions between thousands of receptors at the junction between cells. Owing to the complexity of these processes, understanding immune functions using traditional biological tools is highly challenging. In this talk, I will present my group’s research progress towards designing unique biointerfaces to enable the quantitative understanding and manipulation of immune functions. Our research so far has capitalized on Janus particles, which, like the two-faced Roman god Janus, are made chemically, biologically, optically or magnetically asymmetric. We developed Janus particle-based toolsets for measuring cell dynamics in multi-dimensions beyond translational motion and for spatiotemporally controlling cell functions. Using these methods, we uncovered new dynamics and mechanisms in immune processes, from phagocytosis to intracellular trafficking, which would otherwise be difficult to access with traditional means.

March 19, 2018
10:30 AM
Room 1011, EB1
Dr. Valeria Molinero
University of Utah

Bacteria, insects and fish that thrive at subfreezing temperatures produce proteins that bind to ice and manage its formation and growth. Ice binding proteins include antifreeze proteins and ice-nucleating proteins. The latter are the most efficient ice nucleators found in Nature. Many questions remain on how do these proteins recognize or nucleate ice, what drives their selectivity and binding to ice, and how does the size and aggregation of the proteins modulate their function. In this presentation, I will discuss our recent work addressing these questions using molecular simulations and theory, with particular focus on elucidating what intermolecular interactions and chemical motifs make these proteins so efficient at their function, to resolve the apparent paradox that the same structures can promote and prevent ice formation, and to draw general principles that can be used for the design of synthetic alternatives for control of ice formation and recrystallization.

March 26, 2018
10:30 AM
Room 1011, EB1
Dr. John Falconer
University of Colorado Boulder

Numerous studies have demonstrated that active learning in the classroom instead of traditional lecturing increases student performance and decreases student failure rates. To make it easier for faculty to adopt evidence-based teaching approaches and to provide supplemental materials for students, we have developed teaching resources for most of the chemical engineering core courses. These resources include multiple-choice ConcepTests, short screencast videos, and interactive simulations; they are available at www.LearnChemE.com. Examples of each of these will be presented. We have also prepared resources for students on how to study and learn since most students are not using effective learning approaches.

April 2, 2018
10:30 AM
Room 1011, EB1
Dr. Lokendra Pal
North Carolina State University

Environmental concerns and end-of-life disposal challenges are among the grand challenges for 21st-century society. An examination of renewable resources such as cellulose and its offspring, nanocellulose, offers potential avenues for the mitigation of these issues. Nanocellulose materials are a green platform and have the potential to dramatically impact many commercial markets including barrier coatings and printed electronics due to their high surface area, crystallinity, mechanical strength, transparency, solvent resistance, and tunable chemistry. The application of photonic curing and 3D printing techniques have also created additional interest and possibilities. This presentation will cover recent trends and developments in nanocellulose-based coatings and composites for barrier, and other advanced applications.  For example, cellulose nanofibers have been studied for their excellent oxygen and gas barrier properties. Indeed, they are very sensitive to water and moisture due to hydrophilicity and their amorphous structures, respectively. On the other hand, cellulose nanocrystals (CNC) demonstrate a higher potential to give rise to a barrier coating for fluids, and are less sensitive to moisture. However, due to their high brittleness, coatings and/or films made of CNCs are prone to a greater degree of fractures. Our study exploits the unique properties of CNF and CNC to enhance barrier characteristics and other performance attributes of new generations of packaging products.

April 9, 2018
10:30 AM
Room 1011, EB1
Dr. David Norman
Eastman Chemical Company

Your graduate school experience has taught you to learn new science and engineering fields, identify and solve complex technical problems, and navigate the rigors of the peer review community; but what other skills are required to advance your future industrial career?  The answer is not straightforward. This seminar will therefore provide advice to students on how to understand, improve and apply their strengths to the evolving needs of industry, and insight on career opportunities that a specialty chemical company such as Eastman might offer. Key to understanding and improving your strengths is continual self-analysis of your technical, interpersonal, and leadership gaps, coupled with a desire to give and receive candid coaching and feedback. Knowing when and how to apply your strengths to industrial challenges requires purposeful, yet versatile, thought processes combined with an ability to be passionately objective about your work. Most important, however, is your ability to be an adaptable team member that intuitively understands when to be a facilitator, advocate, opponent, or leader.

April 16, 2018
10:30 AM
Room 1011, EB1
Dr. Hank Ashbaugh
Tulane University

Cavitands are supra-molecular bowl shaped molecules composed of a hydrophobic pocket ringed by acidic groups that make them water soluble. These biomimetic molecules actively bind hydrophobic species in aqueous solution, finding applications in gas separations, delivery vehicles, yoctoliter reactors, etc. The stoichiometry of cavitand hosts bound to hydrophobic guests and the structures formed has been experimentally found to depend sensitively on the size of the hydrophobic guests and the chemistry of the cavitand. In an effort to piece apart the molecular rationale for the assembly of cavitands with hydrophobic guests, we present here a simulation study of the complexes formed between alkanes of varying length and cavtiands that differ simply by degree of methylation. To begin we examine the hydrophobic driving forces for association between a single cavitand and alkane and its relationship to the wetting of the cavitand’s hydrophobic pocket. Next we examine the impact of guest confinement within a dimeric cavitand capsule on the succession of alkane conformational motifs observed with increasing chain length. In the final part of the talk we examine for a methylated cavitand how the length of the encapsulated alkanes impacts the structure of the complex formed from dimeric, to tetrameric, to hexameric cavitand complexes.

April 23, 2018
10:30 AM
Room 1011, EB1
Dr. Vijay John
Tulane University

Our recent work is based on the hydrophobic modification of biopolymers to provide building blocks for supramolecular architectures. The attachment of long chain alkyl groups to the polymer backbone allows the polymer to stick to hydrophobic surfaces and to “hook” onto lipid bilayers. The hydrophobic effect exhibited by such systems can be used to design new functional nanostructures. For example, the use of such polymers to capture and tether liposomes leads to surfaces with densely packed liposomal layers that exhibit very low coefficients of friction in sliding lubrication, representative of articular joints.

We also extend this concept to a system of hydrophobically modified polypeptoids (HMPs) which are amphiphilic pseudo-peptidic macromolecules with hydrophobic groups attached randomly along the polypeptoid backbone. We show that these biocompatible polymers connect across lipid bilayers and thus form layered structures on liposomes. The transition from a single bilayer to multiple bilayer structures is characterized by small angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM).  Of specific interest is the observation that small bilayer rafts reattach to fresh unilamellar liposomes and self-assemble to form new two-bilayered liposomes reminiscent of two-bilayered organelles such as the nucleus in eukaryotic cells. These  observations have significance to designing new nanoscale drug delivery carriers. Initial results on the in-vitro delivery of a highly hydrophobic chemotherapeutic agent, sorafenib, to hepatocellular carcinoma cells will be described.

April 30, 2018
10:30 AM
Room 1011, EB1
McCabe Lecture
Dr. Kathleen Stebe
University of Pennsylvania

We have been developing new strategies, based on geometry, to direct the assembly of colloids in soft matter. By confining soft matter in vessels with well-defined shapes and boundary conditions, we define global energy landscapes. Colloids deform this soft matter; their deformations cost energy. Since these deformations decay over distances similar to the colloids’ diameter, they create an energy field around each colloid that depends on the global energy landscape. As a result, colloids move as if they were in an external applied field.  Examples include colloids at fluid interfaces, colloids adhered to lipid bilayer vesicles and colloids in nematic liquid crystals. In each example, paths, sites for preferred assembly, and structures are defined by the curvature of interfaces and boundaries. New observations in living systems are presented. These assembly strategies give control over system microstructure, and provide new approaches for diverse fields including materials design and control of micro-robots.