1. Relative enhancer-promoter positioning tunes the kinetics of enhancer-mediated transcriptional activity

Emilia Leyes-Porello, Boymi Lim

Gene expression, a tightly regulated process crucial for proper development and health in all living organisms, begins with transcription directed by the interaction between enhancer and promoter regulatory sequences.  In multicellular eukaryotes, the linear distance between these regulatory elements can span tens to hundreds of kilobases, yet their spatial proximity is believed essential for transcription initiation. The impact of enhancer-promoter (E-P) distance and genomic placement on transcriptional dynamics and regulation of key cellular functions remains poorly understood. This study investigates the regulatory mechanisms underlying E-P interactions and their effects on transcriptional activity using Drosophila melanogaster as a model organism. We designed reporter constructs that systematically modulate E-P positioning parameters at distances ranging from 0 to 10 kb. Employing the MS2/MCP live-imaging system, we visualized and quantified real-time transcriptional activity profiles as a function of these parameters. Our findings reveal that increasing E-P distance delays the activation of post-mitotic transcription and decreases mean mRNA production per nucleus. Notably, placing the enhancer downstream of the promoter significantly represses transcriptional output beyond the trend observed with increasing E-P distance. While downstream enhancer positioning does not differentially affect post-mitotic transcriptional activation timing, it significantly reduces the duration of the active transcriptional state compared to upstream positioning. Taken together, these results suggest that increasing E-P distance expands the search space for these elements to find each other, delaying transcription initiation. However, once active, the linear distance does not appear to affect transcriptional state stability. Conversely, enhancer positioning (upstream vs. downstream) does not influence transcription initiation but significantly impacts the stability of the active state. These findings provide new insights into the complex interplay between enhancer-promoter positioning and transcriptional regulation, highlighting the importance of both linear distance and relative genomic placement in shaping gene expression dynamics in eukaryotic organisms.

2. Deciphering Multimerization Strategies for Controlling Liquid-Liquid Phase Separation with Coiled Coils in IDR-Based Membraneless Organelles

Zhihui Su, Daniel Hammer, Matt Good 

In Eukaryotic cells, proteins can undergo natural self assembly and phase separate to form membraneless organelles such as nucleoli, Cajal bodies, P-bodies, and stress granules. Proteins with intrinsically disordered domains (IDRs) can proficiently undergo liquid-liquid phase separation (LLPS) to form condensates that regulate many biological functions. Due to their potential for subcellular compartmentalization and channel-less cargo recruitment and release, membraneless organelles made from LLPS can be excellent bio-building blocks and hubs for cellular communication. In bio-engineered cells and protocells, membraneless organelles offer a brand new alternative platform for cellular functions and expand strategies to facilitate enzymatic communications. Numerous weak interactions between the IDR polypeptides work together to overcome the entropic energy and interfacial free energy costs to create a phase boundary. Higher ordered targeted multimerization of the IDR polypeptides provides fine tuned control for critical concentration and condensate volume. Previously, we demonstrated noncovalent strategies to dimerize two individual IDRs, the LAF-1 RGG domains, to form condensation using cognate coiled coil motifs. Here we develop a high order noncovalent protein IDR multimerization system to generate synthetic membraneless organelles with controllable condensate size and critical concentration. First, we show the optimal cognate coiled coil motif binding configuration for RGG domain dimerization and characterize the dimerization orthogonality through the entire NICP set. Second, we introduce higher ordered IDR multimerization by employing more repeats of coiled coil motifs on both the N or C terminus of the RGG domain. Furthermore, we observe increasing the cognate coiled coil repeats on both termini of the RGG domain suppress phase separation and sequentially decrease the critical temperature. This comprehensive study demonstrated a sophisticated and dynamic RGG coiled coil synthetic system offering a tunable approach and generalizable platform for controlling coacervation valency, and has broad applications such as cargo recruitment and cellular enzymatic control in both bio-engineered cells and protocells.

3. Biomechanics of Upstream Migration in KG1a Cells

Dong-hun Lee, Daniel Hammer

Cell motility is fundamental to immune responses, and understanding it is crucial for advancing cutting-edge therapies like CAR-T, which face challenges in effectively trafficking into tumor sites. Investigating the mechanics behind cell migration, particularly upstream migration under flow, could help refine therapeutic strategies. This study aims to quantify the loci and magnitudes of traction stresses in KG1a cells during upstream migration using Traction Force  Microscopy (TFM) to elucidate the forces driving this movement. KG1a cells were seeded on polyacrylamide gels functionalized with ICAM-1 Fc chimera, to support adhesion. After a 30-minute incubation period, cells were exposed to controlled shear flow. Fluorescence microscopy was used to capture the displacement of fluorescent beads embedded within the gel. LIBTRC software, developed by Micah Dembo and colleagues, was then used to process these images and map the magnitudes of traction stresses. Preliminary findings show that stationary cells exert minimal traction stresses, while actively migrating cells exert significantly higher traction forces. These forces are primarily localized at the uropod, or rear of the cell, highlighting its essential role in driving upstream migration. The results demonstrate that TFM can effectively map the mechanical forces involved in upstream migration, providing greater insights into cell motility. Applying this approach to primary cells could further enhance our understanding of cell migration and support the development of more effective cell-based therapies.

4. On the engulfment of antifreeze protein by ice 

Yusheng Cai, Amish Patel

Antifreeze proteins (AFPs) are remarkable biomolecules that suppress ice formation at trace concentrations. To inhibit ice growth, AFPs must not only bind to ice crystals, but also resist engulfment by ice. The highest supercooling, dT*, for which AFPs are able to resist engulfment is widely believed to scale as the inverse of the separation, L, between bound AFPs, whereas its dependence on the molecular characteristics of the AFP remains poorly understood. By using specialized molecular simulations and interfacial thermodynamics, here, we show that in contrast with conventional wisdom, dT* scales as L− 2 and not as L− 1. We further show that dT* is proportional to AFP size and that diverse naturally occurring AFPs are optimal at resisting engulfment by ice. By facilitating the development of AFP structure–function relationships, we hope that our findings will pave the way for the rational design of AFPs.

5. Critical Analysis of Hydrogen Storage in MXenes

Yamilée Morency, Aleksandra Vojvodic

Hydrogen storage materials are essential for the rapidly expanding hydrogen economy. Recent research has highlighted Ti-based two-dimensional MXenes (specifically Ti2CTx and Ti3C2Tx, where Tx represents surface terminating functional groups) as promising candidates capable of storing more than 8 wt. % of hydrogen. However, there remains a limited understanding at the atomic scale of how and where hydrogen is stored in these materials. In this work, we provide a comprehensive analysis of MXenes’ potential for hydrogen storage and propose a framework for evaluating their storage capabilities. We systematically investigate both molecular and atomic hydrogen uptake in stoichiometric and non-stoichiometric Ti2CTx MXenes with various surface terminations (bare, O, or F). Using a combination of density functional theory (DFT) calculations, experimental hydrogen uptake measurements, and layer-by-layer depth profiling via secondary ion mass spectroscopy (SIMS), we reveal the locations and capacities of intra- and inter-layer hydrogen storage in Ti2CTx. Our findings show that intra-layer hydrogen storage, facilitated by defects and vacancies, is crucial, yielding 1.5 wt. %, while inter-layer storage has a defined upper limit of 0.4 wt. %, achievable only under liquid hydrogen conditions.

6. pH-dependent Interaction between Anionic Silica Nanoparticle and Rare Earth Element (REE) for Selective REE Separation

Ivy Dai, Kathleen Stebe, Daeyeon Lee

Rare earth elements (REEs) are essential for clean energy technologies including batteries for electrical vehicles, wind turbines and LED screens. Silica nanoparticles (SiO2NPs), composed of silicon dioxide, which is the most abundant component in earth’s crust, have gained significant attention in separation processes due to their unique properties such as large surface area and biocompatibility. Therefore, it is of great interest to develop methods using SiO2 NPs for REE recovery and separation to meet the growing demands of a rapidly evolving green economy. This work aims to understand the interactions between REEs and SiO2NPs at different pH conditions. We find that both hydrolysis of REEs and the surface chemistry of SiO2NPs play important roles in their interactions. We explore the interactions of SiO2NPs with REEs at different pH using inductively coupled plasma-optical emission spectroscopy (ICP-OES), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), and zeta potential. We find that SiO2NPs-REE interactions fall into three categories. At low pH, the SiO2NPs have scant charge, and REE- SiO2NP interaction is negligible. At intermediate pH, REEs interact with SiO2NPs via electrostatic interactions. Finally, at high pH, where REEs are fully hydrolyzed into hydroxide precipitates, the two species enter hydrolysis-mediated interaction regime and interact through hydroxyl groups which are present on both REE hydroxide and on the SiO2NPs surfaces. Given that hydrolysis onset for differing REEs is pH dependent, these REE-SiO2NPs  interactions could provide new strategies to selectively adsorb REEs on SiO2NPs and release them in REE recovery and separation processes.

7. The Impact of Direct Hexagonal Mesophase Geometry and Hydration on Ion Motion

Christopher Johnson, Chinedum Osuji

Ion exchange polymer membranes are crucial components in energy generation and separations processes. Investigating the fundamental nature of ion motion within the nanoscale environments in such membranes is critical to developing next generation high selectivity membranes. Highly ordered nanoporous materials present a unique opportunity to elucidate the structure-property correlations that dictate ion transport and selectivity, including the role of morphology and local chemical environment. In this study, we examine highly ordered nanoporous membranes derived from direct hexagonal (HI) lyotropic mesophases and investigate the role of pore size and hydration on the motion of select anions. The mesophase is formed by self-assembly of a positively charged crosslinkable surfactant in water. We vary the pore size, ion identity and the water content systematically by changing the mesophase composition and the relative humidity under which ion transport is studied. From electrochemical impedance spectroscopy measurements, we find that activation energies for ion motion are independent of pore size, implying similar modes of motion, but dependent upon both ion identity and hydration. We also find that there is little dependence of conductivity on pore size when hydration is greater than four waters per charge site, but a much stronger dependence is observed at lower hydration. Ion-specific effects show that deviation from bulk hydration behavior and strength of charge site interactions drive very large differences in conductivity between ions. Tests of long-term ionic conductivity and diffusivity, membrane tensile properties, and solvent resiliency show promise for the use of these materials as desalination membranes. 

8. Modulating the Contact Angle between Nonpolar Polymers and SiO2 Nanoparticles

Anirban Majumder, Daeyeon Lee

Polymer–nanoparticle interactions play an important role in determining the morphology and properties of polymer nanocomposites and controlling the polymeric reactions involving heterogeneous catalysts. Here, we modulate the interactions between nonpolar polymers and nanoparticles by modifying the nanoparticle surface chemistry and quantify the interaction strength through direct contact angle measurements. We investigate the interactions of three nonpolar polymers, polystyrene, polyethylene, and polycyclooctene, with silica nanoparticles whose surface chemistry has been modified by atomic layer deposition of titania and calcium carbonate and by alkyl silanization. Significant differences in polymer–nanoparticle interactions are observed, which can be attributed to differences in the polarizability of the polymers and oxide surface composition. Compared to fully hydrogenated polycyclooctene, polycyclooctene is shown to have stronger interactions with most metal oxides; however, this trend is reversed following alkyl silanization of the silica nanoparticles, which makes the surface of the particles less polar. These differences in interactions can be leveraged to make polymer nanocomposites with unique properties and enable the selective conversion of polymers without the need for separations.

9. Enhancing Solvent Resistance of Polymers by Confinement in Nanoparticle Packings

Trevor Devine, Daeyeon Lee, Robert Riggleman

One of the critical drawbacks of polymer-based products is their poor solvent resistance, as polymers tend to swell, deform and dissolve catastrophically when exposed to good solvents. In this work, we show that infiltrating polymers in the interstices of dense packings of nanoparticles can dramatically enhance their solvent resistance. We are inspired by previous research showing that a tightly bound layer of polymer can form on the solid surface and remain intact even after exposure to good solvents. We investigate whether such seemingly irreversible polymer-surface adsorption affects the solvent resistance of polystyrene (PS) and poly(2-vinyl pyridine) (P2VP) confined within the interstitial pores of a dense SiO2 nanoparticle (NP) packing. We vary the solvent quality, confinement ratio, and polymer-nanoparticle interactions to probe the regime of solvent resistance in these polymer-infiltrated nanoparticle films (PINFs). Polymer-NP interaction strength is weakened through alkyl silanization of the nanoparticle surface.  Our results indicate that polymer-infiltrated nanoparticle films can exhibit remarkable solvent resistance, depending on interstitial pore size, solvent quality, and relative solvent-nanoparticle-polymer interactions. PINFs with the smallest nanoparticles, and thus the smallest pore size, have the strongest solvation resistance. PS-PINFs are less effective at resisting polar solvents, while P2VP-PINFs provide greater protection. Weakening the attractive polymer-nanoparticle interactions by alteration of the nanoparticle surface greatly reduces the solvation resistance. We hypothesize that when pore size is adequately smaller than the adsorbed layer thickness, the solvent is unable to remove polymer chains from the composite. These results present an exciting new technique to provide superior solvent resistance to polymeric materials for enhanced performance and novel applications. 

10. Generation of bubbles within capsules via osmosis-induced-cavitation

CK Yeh, Daeyeon Lee

Inducing buoyancy in capsules would facilitate their separation from undesirable products. While methods like flow cytometry or dielectrophoresis can be used to separate capsules from droplets, they require specialized equipment and skilled operators. To remedy this issue, we created a method that generates bubbles into the core of the capsule for subsequent separation. Although capsules that contain bubbles have been reported, the methods for their fabrication make it difficult to control the size of the bubble and capsule. In this work, we demonstrate the ability to make uniform capsules that contain uniform bubbles via osmosis-induced-cavitation. The method involves taking capsules that have a relatively low concentration of salt inside their core and placing them into a high salt solution, posing a high negative pressure on the water inside the capsule. Under this pressure, the dissolved air can expand into a gas bubble and grow until the inside and outside salt concentration balance. Furthermore, we have been able to show that once these bubbles are grown under the high salt concentration, their size can be modulated by placing the capsules back into lower salt concentrations. Osmosis-induced-cavitation presents a way to introduce bubbles within capsules and modulate their size to allow for separation of capsules.

11. Control of Microfluidics

Owen Land, Warren Seider, Daeyeon Lee

The establishment of precise microscale environments through the formation of microfluidic bubbles and droplets is crucial for advancements in fields such as pharmaceuticals, chemical synthesis, and DNA sequencing. Achieving precise control over the size, shape, and functionality of these entities is essential for their effectiveness over emulsions produced using bulk fabrication methods. Despite efforts to maintain constant external variables such as flow rates and pressures, unpredictable factors can disrupt microfluidic processes, jeopardizing the uniformity of resulting emulsions. In this study, we introduce a two-step soft-sensor approach incorporating a convolutional neural network (CNN) and an image recognition algorithm for feature extraction of the size and aspect ratio of anisotropic hydrogel rods used in tissue repair studies. This method facilitates the detection of flow regimes and enables assessment of emulsion size and aspect ratio, and when integrated with a proportional-integral-derivative (PID) controller, the soft sensor demonstrates effective setpoint tracking of the size and aspect ratio of the hydrogel rods. Through the utilization of the soft-sensor and AI-driven feedback control, our research presents a widely applicable methodology for precise and automated microfluidic control across diverse applications.

12. Predicting the Excess Free Energy of Liquid Mixtures by Biasing Phase Separation in Molecular Dynamics Simulations

Alexander Johnson, Daeyeon Lee, Amish J. Patel

Knowledge of phase behavior is key for designing many chemical systems with examples ranging from reaction engineering and separation processes on the macroscopic scale, to multiphase material design and peptide engineering on the microscopic scale. Quantification of phase behavior is achieved by measuring a liquid mixture’s excess free energy: a coarse-grained descriptor that attempts to capture how the mixture’s many molecular-level interactions deviate from ideality. While molecular-level tools such as molecular dynamics simulations appear well-posed to perform such measurements, special methods are required to probe free energies in simulations. As a result, this work develops an enhanced sampling technique that biases liquid mixtures through different extents of liquid-liquid phase separation (LLPS). By measuring the bias potential strength required to transition a mixture from being homogeneous to phase-separated (or vice versa), excess free energies are obtained by making connection to the thermodynamic theory of LLPS. This biasing method has been successfully demonstrated on model systems of Lennard-Jones fluids and molecular mixtures including acrylamide + water and N-isopropylacrylamide + water monomer solutions. Overall, this work provides a robust methodology for understanding phase behavior in liquid mixtures, with implications for advancing knowledge of LLPS in a variety of chemical contexts including coacervating peptide design and LLPS in the presence of solid surfaces.

13. Understanding polymeric gas separation membranes using molecular simulation

Sam Layding, Entao Yang, Luis Pinto, Zach Wilson, Junyi Liu, Pluton Pullumbi, Rob Riggleman

The use of highly specialized membranes for gas separations processes presents a valuable opportunity for a global shift away from traditional thermally driven, carbon-intensive methods. The vast design space for polymers makes it desirable to explore new materials in silico before synthesizing them to conserve valuable resources. Using a combination of quantum mechanical density functional theory, classical molecular dynamics, and grand canonical Monte Carlo methods, we explore gas permeance behaviors of several materials including ladder polymers, polyimides, and polysulfones using fully atomistic simulations. From the solution-diffusion method we use Grand Canonical Monte Carlo to deduce the solubility of gas molecules with hybrid MD/MC to explore structural changes induced by the solute. Classical molecular dynamics to evaluate gas diffusion coefficients as a function of gas loading. Finally, we note how the use of detailed simulations with atomistic force fields combined with an iterative feedback loop provides an opportunity for the accelerated development of soft materials in important engineering applications.

1. Surface anchoring of LC

Yusheng Cai, Amish Patel

Liquid crystal (LC) molecules, such as 5CB, form nematic phase that has long-range orientational order while retaining translational symmetry. However, surfaces break the symmetry by imposing anchoring conditions that differ from the bulk orientation. The resulting conflict creates low-order and high-energy regions known as topological defects. Defects can drive the self-assembly of nanoparticles by directing them towards defect cores, which reduces the free energy in the system. The ability of LC to di rect self-assembly enables applications such as bottom-up synthesis of optical materials. The self-assembly behavior depends heavily on the surface anchoring conditions which can be modulated by changing surface properties like surface chemistry and roughness. In this study, we use molecular dynamics simulations and enhanced sampling tools to investigate the interactions between 5CB molecules and self-assembled monolayer (SAM) surfaces with diverse end-group chemistries. Our results indicate that non-polar surfaces induce planar alignment of 5CB, while polar surfaces cause the CN head of  5CB to tilt towards the surface to enhance electrostatic interaction, resulting in a tilted configuration.  Furthermore, polar surfaces with dipole pointing along surface normal induce homeotropic anchoring,  where the CN head group is oriented perpendicular to the surface to maximize electrostatic interaction.  Our findings shed light on the underlying atomistic mechanisms that govern surface anchoring on SAM surfaces, offering insights into how to manipulate surface anchoring which can contribute to the rational design of nanoscale self-assembly in LC template.

2. The Impact of Direct Hexagonal Mesophase Geometry and Hydration on Ion Motion

Christopher Johnson, Chinedum Osuji

Ion exchange polymer membranes are crucial components in energy generation and separations processes. Investigating the fundamental nature of ion motion within the nanoscale environments in such membranes is critical to developing next generation high selectivity membranes. Highly ordered nanoporous materials present a unique opportunity to elucidate the structure-property correlations that dictate ion transport and selectivity, including the role of morphology and local chemical environment. In this study, we examine highly ordered nanoporous membranes derived from direct hexagonal (HI) lyotropic mesophases and investigate the role of pore size and hydration on the motion of select anions. The mesophase is formed by self-assembly of a positively charged crosslinkable surfactant in water. We vary the pore size, ion identity and the water content systematically by changing the mesophase composition and the relative humidity under which ion transport is studied. From electrochemical impedance spectroscopy measurements, we find that activation energies for ion motion are independent of pore size, implying similar modes of motion, but dependent upon both ion identity and hydration. We also find that there is little dependence of conductivity on pore size when hydration is greater than four waters per charge site, but a much stronger dependence is observed at lower hydration. Ion-specific effects show that deviation from bulk hydration behavior and strength of charge site interactions drive very large differences in conductivity between ions. Tests of long-term ionic conductivity and diffusivity, membrane tensile properties, and solvent resiliency show promise for the use of these materials as desalination membranes. 

3. Crystallization Behavior of Linear EVOH Analogs from Hydroxylation of Polycyclooctene

Eli Fastow, Anne Radzanowski, E. Bryan Coughlin, Karen I. Winey

Poly(ethylene-co-vinyl alcohol) (EVOH) is a commodity polymer used in multilayer films and valuable for its mechanical, adhesive, and oxygen permeability properties. Commercial EVOH is typically synthesized by free radical polymerization, producing a branched chain and random distribution of co-monomers. Both mechanical properties and permeability typically improve as crystallinity increases, though branching suppresses crystallization. We report the crystallization behavior of linear analogs to EVOH at a range of hydroxyl concentration prepared by partial functionalization then hydrogenation of polycyclooctene. As functionalization increases, the crystallization kinetics and total crystallinity decrease. The crystal structure transitions from orthorhombic at low functionalization (< 17 mol% of ethylene units) to a mixture of orthorhombic and hexagonal at moderate functionalization (17 – 21 mol%), then eventually hexagonal at functionalization exceeding 21 mol%. Notably, we find linear EVOH analogs exhibit nearly double the total crystallinity and crystallization kinetics ten times faster than branched commercial EVOH at the same hydroxyl content.

4. Modulating the Contact Angle between Nonpolar Polymers and SiO2 Nanoparticles

Anirban Majumder, Daeyeon Lee

Polymer–nanoparticle interactions play an important role in determining the morphology and properties of polymer nanocomposites and controlling the polymeric reactions involving heterogeneous catalysts. Here, we modulate the interactions between nonpolar polymers and nanoparticles by modifying the nanoparticle surface chemistry and quantify the interaction strength through direct contact angle measurements. We investigate the interactions of three nonpolar polymers, polystyrene, polyethylene, and polycyclooctene, with silica nanoparticles whose surface chemistry has been modified by atomic layer deposition of titania and calcium carbonate and by alkyl silanization. Significant differences in polymer–nanoparticle interactions are observed, which can be attributed to differences in the polarizability of the polymers and oxide surface composition. Compared to fully hydrogenated polycyclooctene, polycyclooctene is shown to have stronger interactions with most metal oxides; however, this trend is reversed following alkyl silanization of the silica nanoparticles, which makes the surface of the particles less polar. These differences in interactions can be leveraged to make polymer nanocomposites with unique properties and enable the selective conversion of polymers without the need for separations.

5. Coupling Critical Mineral Recovery to Carbon Storage: Separations Engineering of Precipitating Metal Hydroxides

Shelvey Swett, Katherine Vaz Gomes, Hélène Pilorgé, Jennifer Wilcox

Climate change is undeniably an urgent global problem. Experts agree, to minimize the worst effects, we must approach complete decarbonization by 2050. Critical minerals are essential for global decarbonization, particularly to industries like electric vehicles (Li, Co, Mn, Ni), electrification (Cu), and solar PV (Al, Cu). With increasing demand for these elements in the energy transition, we are challenged to obtain them in a manner that is just, technically and economically viable, and minimizes carbon emissions and harmful environmental impacts. Scaling the separation processes to meet the demands of these booming industries while maintaining these tenets presents an added challenge. We also face the challenge of the energy demands of classical and effective separations. Methods like distillation and solvent extraction have higher energy and reagent demand compared to processes like membrane separation and crystallization. This demand can increase as we seek outputs of higher purity commanded by critical metal markets. Magnesium and calcium silicate minerals found in mining waste are a scalable source of alkaline earth metals (Mg, Ca)—which form durable carbonate products when reacted with CO2—and critical minerals (Fe, Co, Mn, Ni) for energy transition industries. We approach the separation of these elements though an indirect carbonation pathway. Both critical metals and alkaline elements are extracted through acid dissolution at temperature. The leachate output moves to a 3-stage chemical precipitation process, targeting the selective separation of solid metal hydroxides based on their intrinsic pH-dependent solubilities. We aim to optimize the separation throughput and purity of both critical metals and alkaline earth metals with process design informed by techno-economic modeling. The current engineered process achieves 89% separation of a 90% pure Mg(OH)2 solid product. At scale, with 100% conversion of Mg(OH)2 to MgCO3, this process could store 0.33 tCO2 per tonne tailings and provide a competitive pathway for low-carbon metal production. These results will inform a strategic roadmap for use of other mineral feedstocks in economy-wide decarbonization efforts. Specifically, this work will foster a clearer understanding of the chemical and physical properties of the mine tailing feeds and economic metal recoverability. 

6. 3D printing of bicontinuous nanoparticle-stabilized emulsion gels 

Philip R. Iaccarino, Damilola Lawal, Jordan R. Raney, Daeyeon Lee, Kathleen J. Stebe 

Bijels are particle-stabilized structures consisting of a network of two bicontinuous phases,  typically formed by kinetically arresting spinodal decomposition through interfacial jamming of particles along the interface of the two phases. Previously, our groups have developed solvent transfer-induced phase separation (STrIPS) and vaporization-induced phase separation (VIPS)  methods for bijel fabrication; in these approaches, phase separation is induced by the removal of cosolvent from a homogeneous ternary solution of oil-water-cosolvent. These co-solvent removal techniques have been used to make bijel structures such as particles, fibers, and membranes. In this work, we present 3D printing of bijels via direct ink writing (DIW). 3D printing of bijels using the conventional precursors is challenging because they lack rheological requirements to support  DIW 3D printing. To overcome this challenge, bijel precursors are modified to possess enhanced rheology to promote layering of materials and shape retention, while simultaneously allowing for the development of bicontinuous morphology. These 3D printable bijel “inks” are prepared using a mixture of commercially available hydrophilic and hydrophobic fumed silicas, which promote gelation in the bijel precursor. This gelation induces yield stress and shear-thinning rheology into the precursor to support 3D printing. The thixotropic behavior of fumed silica also allows for particle restructuring after extrusion, facilitating bijel formation via VIPS solvent evaporation. We demonstrate 3D printing capabilities by fabricating bijels with varying design complexity with morphologies on centimeter-sized length scales. Further, the bicontinuous microstructure of 3D  printed bijels is explored through confocal and scanning electron microscopies, where submicron sized domains are generated. This technique allows for production of hierarchical, surfactant-free,  biphasic structures with customizable morphologies; these materials are of particular interest for applications in energy storage, bio-scaffolding, catalytic reactors, and biomedical devices. 

7. Transport in blood clot microenvironments: the integration of bio-imaging, machine learning, and physics driven simulation to model molecular diffusion within hemostatic thrombi formed in-vivo

Catherine House, Talid Sinno

When formed in vivo, murine hemostatic thrombi exhibit a heterogeneous architecture comprised of distinct regions of densely and sparsely packed platelets. In this study, we aim to utilize high-resolution electron microscopy alongside machine learning and physics-based simulations to investigate how such clot microstructure impacts chemical signal propagation. We used Serial Block Face – Scanning Electron Microscopy (SBF-SEM) to image select volumes of hemostatic masses formed in a mouse jugular vein, producing large stacks of 2D images. Images were segmented using a machine learning software (Cellpose) augmented by few manually segmented images. The segmented images were then utilized as a computational domain for Lattice Kinetic Monte-Carlo (LKMC) simulations. This process constitutes a computational pipeline that combines purely data-derived biological domains with physics-driven simulations to estimate how molecular movement is hindered in a hemostatic platelet mass. Using our pipeline, we estimated that the hindered diffusion rates of a globular albumin-sized protein range from 2% to 40% of the unhindered rate, with denser packing regions lending to lower molecular diffusivity. These data suggest that coagulation reactions rates, thrombin generation and activity, as well as platelet releasates activity may be drastically impacted by the internal geometry of a hemostatic thrombus.

8. Gold Nanoparticle Size-Selective Adsorption in a Covalently Bonded Weak Polyelectrolyte Brush

Katie Sun, Ye Chan Kim, Russell J. Composto, and Karen I. Winey

The adsorption of spherical citrate-coated gold nanoparticles (AuNPs) into poly(2-vinylpyridine) (P2VP) brushes was investigated using quartz crystal microbalance with dissipation (QCM-D). This study examined the impacts of environmental pH and brush molecular weight (10 and 53 kg/mol) on AuNP adsorption kinetics and areal number densities. We synthesized and characterized the P2VP brushes, grafted-to a poly(glycidyl methacrylate) (PGMA) priming layer, on both silicon wafers and QCM-D sensors. Adsorption experiments explored the pH-dependent adsorption behavior of 10- and 20-nm diameter AuNPs. The QCM-D data show that higher molecular weight brushes enhanced AuNP uptake. At pH = 4.0, the swollen brushes promote greater adsorption compared to the collapsed brush state at pH = 6.2. This study establishes the pH-mediated size-selectivity of these P2VP brushes, with smaller 10-nm AuNPs showing preferential adsorption at higher pH. These findings provide insights into the impacts of brush molecular weight and environmental conditions on nanoparticle adsorption, with implications for designing smart surfaces for sensing and filtration applications.

9. A molecular understanding of the fracture process of model end-linked polymer networks

Han Zhang, Robert Riggleman

A molecular understanding of the fracture process of model end-linked polymer networks  

The fracture of end-linked polymer networks and gels strongly affects the performance of these versatile and widely used materials, and a molecular-level understanding of the fracture energy is important to the design of new materials. The Lake-Thomas theory serves as a framework to understand and quantify the energy dissipation due to the chain scission in these materials based on an idealized picture of fracture in networks. Recent extensions of the Lake-Thomas theory have incorporated the effect of topological defects, such as loop defects, and in some examples enabled accurate prediction of the fracture energy. In this poster, I will describe how we use coarse-grained molecular dynamics simulations and network analysis techniques to provide a molecular view of the energy dissipated during chain scission in polymer networks. In addition to the energy of the broken strand, we also consider the amount of energy released by the networks connected to the broken chain. Network analysis techniques are used to further understand how the inhomogeneous nature of network structure affects energy and stress transmission in polymer networks.  Network analysis also provides a surprisingly effective approach to identifying potential failure locations in our model. Our results can be used to further refine the description of the processes at play during the failure of polymer networks. 

10. Ionic Conductivity in Solvent-Swollen Polymer Electrolyte Thin Films

Benjamin T. Ferko, Benjamin Ketter, Zhongyang Wang, Paul F. Nealey, Karen I. Winey

Polymer electrolytes, having favorable mechanical properties and good stability, are ideal candidates for overcoming the flammability hazards associated with the liquid electrolytes used in commercialized lithium-ion batteries. Previously, bulk samples of multiblock copolymers consisting of alkyl blocks of a fixed length (x) strictly alternating with polar blocks containing lithium sulfonate groups (PESxLi) form layered morphologies at room temperature. Selectively swelling the polar domains of these multiblock copolymers with DMSO increased the ionic conductivity by 10^4 while maintaining the layered morphology in the bulk. To reduce the role of morphological defects (i.e. grain boundaries) on the conductivity measurements, this study fabricates well-aligned thin films by spin coating and uses interdigitated electrodes to measure Li conductivity. Thin films of PESxLi spontaneously form layered morphologies aligned parallel to the substrate, such that the interdigitated electrodes measure the in-plane conductivity. We report on our progress towards measuring the conductivity of solvent swollen, aligned layers of PESxLi thin films. Custom fabricated solvent chambers permit both grazing incidence X-ray scattering and electrochemical impedance spectroscopy measurements under controlled solvent vapor environments at temperature. These experiments facilitate direct comparisons to all atom molecular dynamics simulations and promise to improve the understanding of how solvent impacts ionic conductivity in nanostructured single-ion conducting polymers. 

*Support was provided by NSF DMR (1904767). The authors acknowledge use of the Dual Source and Environmental X-ray Scattering facility operated by the Laboratory for Research on the Structure of Matter at the University of Pennsylvania supported by NSF through (DMR-2309043).

11. Harnessing Interaction Heterogeneity as a Control Parameter for Colloidal Self-Assembly

Po-Ting Wu, John Crocker, Talid Sinno

Nano- to microscale colloidal particles exhibiting short-ranged attractions are important constituents in a broad range of materials, including foods, cosmetics, paints, and pigments. An example of a short-ranged attractive colloidal system is one in which nano- or microparticles are functionalized with complementary single-stranded DNA oligomers that create reversible energetic interparticle ‘bonds’ with precisely controllable strengths. Despite the many successful demonstrations of novel crystals and disordered structures formed with DNA-based colloids, some persistent issues have prevailed, particularly for larger particle sizes. This bias is readily apparent when comparing the relatively rich library of structures that has been achieved with DNA-grafted nanoparticles (e.g., smaller than 100 nm) to that for micron scale particles. In fact, micron scale DNA-grafted particles often fail to nucleate crystals or form different structures than expected. Assembly difficulties at the micron scale have been attributed to one or more factors, including low DNA grafting density, slow binding kinetics, patchy grafting, or a very narrow temperature window for nucleation. Here, we study a previously unappreciated feature of DNA-grafted particles—heterogeneity in the interaction strengths between particle pairs. For DNA-grafted particles, this may be a consequence of each colloid having a different number of DNA strands on its surface resulting from natural stochasticity in the grafting process. We have previously shown that interaction heterogeneity can favorably modify the nucleation of crystallites by ‘spreading out’ the nucleation process and inhibiting gelation. In the present study, we first examine the thermodynamic impact of interaction heterogeneity (IH) by constructing fluid-crystal bulk phase diagrams for systems exhibiting different extents of ‘natural’ IH, i.e., that which is expected to arise unintentionally from the particle fabrication process. Overall, we find that the presence of natural IH leads to the stabilization of the fluid phase, while the crystal phase tends to be enriched in ‘stronger’ colloids, i.e., those exhibiting larger binding energies. Using a highly idealized model of IH in which only two types of particles are present—strong and weak—we study further the possibility of using intentionally designed IH to modulate nucleation and crystallization of colloids. Our findings suggest that IH can be exploited to modulate colloidal self-assembly.

12. Phase Behavior in Ion-Containing Block-Copolymers with Sterically Demanding Pendant Groups

Margaret Brown, Karen I. Winey

The double gyroid morphology (DG) is a triply periodic bicontinuous morphology observed in some self-assembling polymer systems, associated with improved performance such as enhanced mechanical properties and conductivities. We have previously observed this morphology in a strictly alternating block copolymer comprised of a short sodium-sulfonated polar block and a linear alkyl block of 12-23 carbons (PESxNa). These materials crystallize into layers at room temperature and transition to the DG morphology above their melting point, suggesting that the crystallization of the alkyl blocks prevents the DG from forming at lower temperatures. In this work, new multiblock copolymers (PESxNa-R) were synthesized to disrupt crystallinity by either  (1) adding an isopropyl group to the center of each alkyl block or (2) replacing 20% of the linear alkyl blocks with branched alkyls. In simple diblock copolymers the volume fraction of the two blocks and to a lesser extent  temperature determine the self-assembled morphology. In PESxNa, the DG was previously  observed above Tm when the volume fraction of the polar block was 0.27 to 0.41. Although the  new PESxNa-R copolymers are in the same range (0.29-0.39), X-ray scattering experiments  show that while both backbone modifications reduce or eliminate crystallinity, a layered or  hexagonal morphology forms rather than the expected DG. We interpret this result by  considering the amount of chain stretching required to form the DG using the medial packing  model created by the Prof. Greg Grason’s group. From the volume fraction and lattice parameter,  this model computes the thicknesses of the major and minor domains that we compare to the  fully extended lengths of our multiblock copolymers. Compared to PESxNa, PESxNa-R significantly increases the degree of chain stretching required to form the DG. This highlights the importance of chain stretching on the stability of the DG in multiblock copolymers with short blocks.

13. Micro robotic manipulation of oil-paramagnetic nanoparticle suspensions 

Oluwafemi Ligan, Dr Kathleen Stebe

Iron oxide nanoparticles (IONP) assemblies have a great potential in applications that exploit their  ability to form functional structures that can deliver cargo. The relative safety of magnetic fields  and their ability to penetrate biological tissues make these assemblies particularly attractive for  biomedicine. Our groups have developed micro robotic systems based on IONP assemblies to kill,  degrade and remove deleterious biofilms with remarkable efficiency. Here, we study IONP that  are initially free in aqueous solution that interact with oil drops. The IONP are manipulated using 3D-Helmholtz coils. The coils generate a magnetic field designed to set up a field that rotates about  an axis parallel to the surface. The IONP interacts with the droplets and the field to form a series  of structures with distinct symmetries. We find that these structures move effectively by a ‘walking’ motion that minimizes drag with bounding surfaces. We summarize the range of  structures and their motions and present a rationale for their formation based upon interactions  with the external field and adhesion to the droplet surface. Future work will exploit these structures  as microrobots to carry, transport and deliver hydrophobic antibacterial and antifungal essential  oils to treat a biofilm infection

14. Adsorption and selectivity of lanthanide-binding peptides at the air-water interface quantified by confocal laser scanning microscopy

Stephen A. Crane, Jason G. Marmorstein, E. James Petersson, Kathleen J. Stebe, and Ivan J. Dmochowski

Rare earth elements (REEs) are crucial to modern technologies. These elements are notoriously difficult to separate from each other owing to the similar diameters of the REE cations and the fact that they are typically present in the +3-oxidation state. Currently, REE separation is largely carried out in liquid-liquid extraction processes that are energetically and environmentally burdensome. We seek to develop a green and efficient REE separation process that exploits peptide surfactants (PEPS) that selectively bind REEs in a binding loop motif and sequester them in the air-water interfaces of foam via a froth flotation process. In our prior work, we have shown that bulk and interfacial selectivity for REEs binding to PEPS differ significantly. MD simulation shows that the binding loop conformation changes subtly with different REEs. We hypothesize that these REE-induced structural changes confer differences in surface activity among the REE:PEPS complexes. To probe this concept, we incorporate the unnatural amino acid, acridon-2-ylalanine (Acd), into PEPS and image air-water interface of PEPS solutions using confocal laser scanning microscopy (CLSM). By measuring the spatial intensity distribution of Acd fluorescence, we quantify the surface concentration of PEPS and REE:PEPS complexes. Additionally, the Acd fluorophore can sensitize the luminescence of Eu3+ captured by PEPS via FRET, thereby diminishing the Acd fluorescence intensity. Other REEs, when present in the binding loop, do not reduce Acd emission as significantly, which allows ratiometric measurements of REE versus Eu3+ selectivity in the bulk and at the interface. With these tools, we measure the dynamics of adsorption of different REE:PEPS complexes and complement these measurements with parallel dynamic surface tension studies. We find that light REE:PEPS complexes adsorb to the air-water interface with faster kinetics than heavy REE:PEPS complexes. This difference in adsorption kinetics is consistent with the discrepancy between bulk and interfacial selectivity and can provide a basis for selective REE capture. 

15. Orthogonal and multiplexable genetic perturbations with an engineered prime editor and a diverse RNA array

Tyler Daniel, Xue Gao

Molecular tools that can precisely modify DNA and control gene expression are crucial for advancing biological research and treating genetic diseases. In this study, we introduce mvGPT (Minimal Versatile Genetic Perturbation Technology), a flexible and compact toolkit capable of simultaneously editing, activating, and silencing different genes in human cells. The mvGPT platform uses an optimized Prime Editor for precise gene editing, a DNA polymerase recruitment system for gene activation, and a small interfering RNA to silence endogenous genes, enabling easily programmable and multiplexed genetic perturbations. We showcase the potential of this technology by simultaneously correcting a pathogenic mutation in the ATP7B gene associated with Wilson’s disease, activating PDX1 to potentially treat Type 1 diabetes, and silencing TTR to manage clinical symptoms of transthyretin amyloidosis. Additionally, we demonstrate that mvGPT is compatible with multiple modern delivery systems including plasmid delivery, AAV, and lentiviral integration, highlighting its potential for future medical applications.

16. Predicting the Excess Free Energy of Liquid Mixtures by Biasing Phase Separation in Molecular Dynamics Simulations

Alexander Johnson, Daeyeon Lee, Amish J. Patel

Knowledge of phase behavior is key for designing many chemical systems with examples ranging from reaction engineering and separation processes on the macroscopic scale, to multiphase material design and peptide engineering on the microscopic scale. Quantification of phase behavior is achieved by measuring a liquid mixture’s excess free energy: a coarse-grained descriptor that attempts to capture how the mixture’s many molecular-level interactions deviate from ideality. While molecular-level tools such as molecular dynamics simulations appear well-posed to perform such measurements, special methods are required to probe free energies in simulations. As a result, this work develops an enhanced sampling technique that biases liquid mixtures through different extents of liquid-liquid phase separation (LLPS). By measuring the bias potential strength required to transition a mixture from being homogeneous to phase-separated (or vice versa), excess free energies are obtained by making connection to the thermodynamic theory of LLPS. This biasing method has been successfully demonstrated on model systems of Lennard-Jones fluids and molecular mixtures including acrylamide + water and N-isopropylacrylamide + water monomer solutions. Overall, this work provides a robust methodology for understanding phase behavior in liquid mixtures, with implications for advancing knowledge of LLPS in a variety of chemical contexts including coacervating peptide design and LLPS in the presence of solid surfaces.

17. Harnessing Geothermal Energy for Carbon Dioxide Removal: An Integrated Direct Air Capture and Indirect Carbonation Process

Shrey Patel, Maxwell Pisciotta, Jennifer Wilcox

In this study, we propose a renewable carbon dioxide removal (CDR) process that integrates  Direct Air Capture (DAC) and Indirect Carbonation (IDC), both powered by geothermal energy. The process is designed to capture and permanently store 0.25 million tonnes of CO2  annually, utilizing geothermal brine to meet the heat requirements of DAC while also generating electricity through an Organic Rankine Cycle (ORC). This dual use of geothermal energy significantly improves its carbon abatement potential compared to its traditional application for green electricity generation, where energy conversion efficiency is typically low  (~12%). The integration of DAC with IDC offers a full carbon removal pathway. In the IDC step, we utilize mine tailing waste from ultramafic rock mines (like magnesium-rich Twin Sisters Olivine) to sequester the captured CO2 as magnesium carbonate, providing a sustainable and permanent storage solution with potential industrial applications. ASPEN Plus simulations were used to model the process and optimize the heat utilization and electricity production.  Additionally, a sensitivity analysis was conducted to understand how changes in the energy requirements of DAC+IDC affect the production of geothermal electricity and thus, the dependence on external electricity (sourced from on-site Solar facility) and the total land requirements. This study highlights the potential for regions with abundant and accessible geothermal resources to implement a sustainable carbon removal solution. By using renewable geothermal energy to power both DAC and IDC, we provide a scalable option for reducing atmospheric  CO2 levels. Although the CO2 abatement potential is improved, large-scale deployment of such technology depends significantly on factors like creation of a robust supply chain ecosystem, energy security, community acceptance, and socio-economic incentives. This work could serve as a guide for industries and nations looking to develop complete carbon removal infrastructure utilizing low-carbon heat and electricity resources.

18. Understanding polymeric gas separation membranes using molecular simulation

Sam Layding, Entao Yang, Luis Pinto, Zach Wilson, Junyi Liu, Pluton Pullumbi, Rob Riggleman

The use of highly specialized membranes for gas separations processes presents a valuable opportunity for a global shift away from traditional thermally driven, carbon-intensive methods. The vast design space for polymers makes it desirable to explore new materials in silico before synthesizing them to conserve valuable resources. Using a combination of quantum mechanical density functional theory, classical molecular dynamics, and grand canonical Monte Carlo methods, we explore gas permeance behaviors of several materials including ladder polymers, polyimides, and polysulfones using fully atomistic simulations. From the solution-diffusion method we use Grand Canonical Monte Carlo to deduce the solubility of gas molecules with hybrid MD/MC to explore structural changes induced by the solute. Classical molecular dynamics to evaluate gas diffusion coefficients as a function of gas loading. Finally, we note how the use of detailed simulations with atomistic force fields combined with an iterative feedback loop provides an opportunity for the accelerated development of soft materials in important engineering applications.

19. Deciphering Multimerization Strategies for Controlling Liquid-Liquid Phase Separation with Coiled Coils in IDR-Based Membraneless Organelles

Zhihui Su, Danial A. Hammer, Matt Good

In Eukaryotic cells, proteins can undergo natural self assembly and phase separate to form membraneless organelles such as nucleoli, Cajal bodies, P-bodies, and stress granules. Proteins with intrinsically disordered domains (IDRs) can proficiently undergo liquid-liquid phase separation (LLPS) to form condensates that regulate many biological functions. Due to their potential for subcellular compartmentalization and channel-less cargo recruitment and release, membraneless organelles made from LLPS can be excellent bio-building blocks and hubs for cellular communication. In bio-engineered cells and protocells, membraneless organelles offer a brand new alternative platform for cellular functions and expand strategies to facilitate enzymatic communications. Numerous weak interactions between the IDR polypeptides work together to overcome the entropic energy and interfacial free energy costs to create a phase boundary. Higher ordered targeted multimerization of the IDR polypeptides provides fine tuned control for critical concentration and condensate volume. Previously, we demonstrated noncovalent strategies to dimerize two individual IDRs, the LAF-1 RGG domains, to form condensation using cognate coiled coil motifs. Here we develop a high order noncovalent protein IDR multimerization system to generate synthetic membraneless organelles with controllable condensate size and critical concentration. First, we show the optimal cognate coiled coil motif binding configuration for RGG domain dimerization and characterize the dimerization orthogonality through the entire NICP set. Second, we introduce higher ordered IDR multimerization by employing more repeats of coiled coil motifs on both the N or C terminus of the RGG domain. Furthermore, we observe increasing the cognate coiled coil repeats on both termini of the RGG domain suppress phase separation and sequentially decrease the critical temperature. This comprehensive study demonstrated a sophisticated and dynamic RGG coiled coil synthetic system offering a tunable approach and generalizable platform for controlling coacervation valency, and has broad applications such as cargo recruitment and cellular enzymatic control in both bio-engineered cells and protocells.

20. Autonomous Motion of Enzymatically Driven Janus and non-Janus Micromotors

Amanda Hopkins, Daniel Hammer, Daeyeon Lee

Cellular motion is a dynamic process that plays a critical role in immunology, tissue assembly,  and physiological homeostasis. Cell-like motility of artificial cells, or protocells, has the potential to enhance biologist’s understanding of complex cellular processes and to develop new technologies related to drug delivery, biochemical sensing, and cell-to-cell signaling.  Understanding the fundamental requirements for protocell motion would provide insights into cellular motion and lead to the development of new technologies for building responsive protocells that could sense and respond to environmental stimuli. In this work, we use the notion that enzymes, when converting substrates to products, can exert forces. Our group recently used this idea to illustrate the enzyme-driven motion of cell-sized, urease-functionalized poly(lactic-co-glycolic acid) (PLGA) microcapsules. These capsules were intentionally developed with a  non-uniform enzyme distribution on their shell; enzyme asymmetry has been hypothesized to be the driving force for enhanced motion. In our current work, we have made asymmetric Janus microparticles using microfluidic assembly to test whether asymmetric particles can display enhanced motion. We fabricated Janus microparticles using a mixed polymer system, blending  the polymers PLGA and polycaprolactone (PCL). These two polymers partially phase separate during dewetting. Protein conjugation via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) targets carboxylic acid functional groups which are only present on one lobe of the Janus particle, creating an inherent asymmetry in both shape and enzyme functionalization. This asymmetry can propel Janus particles functionalized with urease. Active motion of these particles provides direct measurements of the relationship between direction of motion and the axis of asymmetry of the Janus particles. We are exploring the relationship between capsule size,  capsule asymmetry, enzyme density and enzyme type and the avidity of capsule motion. 

21. Functionalizing Polymerizable Surfactant Mesophases for Organic Solvent Separations

Jack Granite, Chinedum Osuji

Membrane technologies such as nanofiltration hold promise to achieve highly selective separations, reducing energy costs in some cases by a factor of 2–3. Recent developments in nanostructured materials derived from self-assembled systems, such as polymerizable surfactant mesophases (PSMs), have shown great potential for separating large molecules from aqueous media with state-of-the-art permeability and size selectivity because of their monodisperse pore sizes. Currently, PSMs lack tunability in their chemical selectivity, which is crucial for bulk organic solvent separations. My work seeks to develop functionalized PSMs using modular surfactants to independently tune size selectivity, chemical selectivity, and permeability. I have utilized new reagents in Menshutkin reactions to synthesize quaternary ammonium surfactants featuring head groups of increased hydrophobicity and steric hindrance (methyl, ethyl, isopropyl) and am investigating new reaction pathways to create hydrophilic head groups. Small-angle x-ray scattering and polarized optical microscopy indicate that these (or blends of these) new surfactants exhibit hexagonally packed cylindrical and cubic phases, indicating the potential for PSMs to exhibit combined size and chemical selectivity in organic solvent nanofiltration.

22. Oxidative catalytic conversion of linear alkanes over titanium silicate toward chemical upcycling of plastic waste

Seyeon Park, John Vohs, Raymond Gorte, and Daeyeon Lee

We systematically investigated the oxidative transformation of linear alkanes ranging from n C8H18 to n-C36H74 into ketones and alcohols using titanium silicate-1 catalysts, aiming to understand how to functionalize larger polyolefins. Reactions were conducted in a biphasic medium of organic alkanes and aqueous H2O2, with the addition of catalysts. Our findings indicate that reaction rates are significantly influenced by alkane chain lengths and solvent properties.  Notably, rates exponentially decreased with longer alkanes due to decreased solubility into aqueous phase. Methyl ethyl ketone significantly enhanced oxidation rates by at least a factor of  20 compared to acetonitrile as a solvent. Further investigation using solvents with varying octanol water partition coefficients revealed that alkane partitioning in the water-rich phase is pivotal for enhancing oxidation rates. 1H NMR spectroscopy elucidated that the primary oxidation products are ketones, with some alcohols also being formed. Quantitative analyses of the spectra indicated a preferential reaction at the 2 positions in the alkanes, while central carbons were also involved in the reaction. Altogether, this investigation provides insights into how to utilize this catalytic approach to transform polyolefins into oxidized products.

23. Critical Analysis of Hydrogen Storage in MXenes

Yamilée Morency, Aleksandra Vojvodic

Hydrogen storage materials are essential for the rapidly expanding hydrogen economy. Recent research has highlighted Ti-based two-dimensional MXenes (specifically Ti2CTx and Ti3C2Tx, where Tx represents surface terminating functional groups) as promising candidates capable of storing more than 8 wt. % of hydrogen. However, there remains a limited understanding at the atomic scale of how and where hydrogen is stored in these materials. In this work, we provide a comprehensive analysis of MXenes’ potential for hydrogen storage and propose a framework for evaluating their storage capabilities. We systematically investigate both molecular and atomic hydrogen uptake in stoichiometric and non-stoichiometric Ti2CTx MXenes with various surface terminations (bare, O, or F). Using a combination of density functional theory (DFT) calculations, experimental hydrogen uptake measurements, and layer-by-layer depth profiling via secondary ion mass spectroscopy (SIMS), we reveal the locations and capacities of intra- and inter-layer hydrogen storage in Ti2CTx. Our findings show that intra-layer hydrogen storage, facilitated by defects and vacancies, is crucial, yielding 1.5 wt. %, while inter-layer storage has a defined upper limit of 0.4 wt. %, achievable only under liquid hydrogen conditions.

24. Encapsulation of Bioactive Compounds in Oil-in-water Microcapsules

Ekta Jagtiani, Chinendum Osuji

Oil-in-water emulsions are one of the most studied type of dispersions and several applications in food, pharmaceuticals, cosmetics has a common objective of successful encapsulation. Cellulose nanofibers (CNFs) have appeared as potential candidates to stabilize emulsions for their special characteristics, including high aspect ratio and surface area, mechanical strength permitting effective adsorption at the oil-water interface. Among the bioactive compounds used for encapsulation, carvacrol seems to be promising as it is a bioactive compound widely studied for its potential applications in pharmaceutical, nutraceutical and food industries offering numerous health benefits. The stability of such emulsions is largely determined by the oil-to-water ratio, CNF concentration, pH and ionic strength which affect microcapsule size distribution, creaming tendency and stability of overall emulsion. The influence of these factors is interconnected and understanding their interaction is critical while formulating emulsions that are stable at different environmental conditions with desired encapsulation efficiency being the goal. The present study systematically examines the influence of these parameters on CNF-stabilized oil-in-water emulsions properties for encapsulating carvacrol to highlight insights relevant for designing more efficient and stable emulsions for industrial applications.

25. Enhanced mineral carbonation on surface functionalized MgO derived from mine tailings

Yingjie Shi, Aleksandra Vojvodic

The rising demands of industrialization highlight the need for efficient, scalable Carbon  Capture and Storage (CCS) methods. Mineral carbonation of MgO shows promise due to its high CO2 adsorption capacity, but its slow reaction kinetics remain a significant challenge.  This study investigates the structural and chemical changes in MgO carbonation, sourced from various mine tailings, using electron microscopy. Results reveal that treating MgO with polar solvents significantly enhances carbonation, with particle size and Si-based additives further accelerating the process. Density functional theory (DFT) calculations provide insight into surface functionalization as a result of solvent treatment and its mechanistic effect on the origin of the enhanced carbonation of polar solvent-treated MgO, revealing a stronger interaction between CO2 and the treated MgO (100) surface as compared to the non-polar solvent treated surfaces. These discoveries showcase an alternative approach for enhancing MgO carbonation, thereby offering a potential method for sequestering atmospheric CO2 more effectively using mine waste rich in MgO.

26. Ion-specific Effects on the Rheology of Cellulose Nanofibrils (CNFs)

Ravisara (Ning) Wattana, Chinedum Osuji

Cellulose nanofibrils (CNFs), with their high aspect ratio and surface modification ability,  are effective rheology modifiers in aqueous and offer a sustainable alternative for formulating complex fluids due to their abundant origin. This work investigates the rheological behavior of CNF suspensions and gels in the presence of salts, focusing on ion-specific effects that have yet to be extensively studied with CNFs. Additive-free CNF  suspensions exhibit viscoelasticity and shear-thinning behavior, with a transition occurring at 0.5 wt.%, which distinguishes the boundary between dilute and semidilute regimes. In these regimes, the storage modulus and specific viscosity follow power-law relationships with CNF concentration, with exponents of ~1 and ~5, respectively. The addition of salts significantly enhances the elasticity of the suspensions, with the storage modulus demonstrating a power-law dependence on ion hydration enthalpy, a pattern similar to the Hofmeister Series (HS). The Cole-Cole plots show a single-time relaxation process influenced by specific ion effects. Meanwhile, intrinsic viscosity decreases as salt concentration increases, indirectly aligning with the HS. This reduction in viscosity suggests that CNF conformations, including their flexibility and shape, are affected by the hydrogen-bonding network of water, which is modified by different ion species. These ion-specific interactions highlight the influence of salts on the rheological properties and their implication on molecular conformations of CNFs in the suspension, offering a better understanding of how ionic environments impact CNF behaviors. The findings contribute to the broader knowledge of CNF and salt interactions, providing insights that could help guide the precise engineering of CNF-based materials for various applications where the control of suspension properties is critical.

27. –Abstract Withdrawn–

Hoang Dinh, Daeyeon Lee, Kathleen Stebe

28. Generation of bubbles within capsules via osmosis-induced-cavitation for capsule separation

CK Yeh, Daeyeon Lee

Inducing buoyancy in capsules would facilitate their separation from undesirable products. While methods like flow cytometry or dielectrophoresis can be used to separate capsules from droplets, they require specialized equipment and skilled operators. To remedy this issue, we created a method that generates bubbles into the core of the capsule for subsequent separation. Although capsules that contain bubbles have been reported, the methods for their fabrication make it difficult to control the size of the bubble and capsule. In this work, we demonstrate the ability to make uniform capsules that contain uniform bubbles via osmosis-induced-cavitation. The method involves taking capsules that have a relatively low concentration of salt inside their core and placing them into a high salt solution, posing a high negative pressure on the water inside the capsule. Under this pressure, the dissolved air can expand into a gas bubble and grow until the inside and outside salt concentration balance. Furthermore, we have been able to show that once these bubbles are grown under the high salt concentration, their size can be modulated by placing the capsules back into lower salt concentrations. Osmosis-induced-cavitation presents a way to introduce bubbles within capsules and modulate their size to allow for separation of capsules.

29. Comparison of batch reactor and flow reactor for hydrogenolysis reaction of long-chain alkane

Zhuoming Feng, John M. Vohs, Raymond J. Gorte

The hydrogenolysis of long-chain alkanes was studied under differential conditions over Ru/SiO2 catalysts using a continuous flow reactor and batch reactor. We noticed that the reaction rates are different in these two reactors. The conversion in the batch reactor is larger than the flow reactor when we use the same temperature and keep the WHSV the same in these two cases. The product distribution and relatively low conversion indicate some limitations in the flow reactor. We are trying to determine the reason for these two reactors’ conversion and product distribution differences. 

References

[1]   Siwon Lee; John M. Vohs, Raymond J. Gorte, Chemical Engineering Journal., Vol (2023) 456. 

30. Selective Interactions between Polymers and Porous Solids for Polymer Upcycling: Solventless Polymer Separation and Tunable Gas Solubility

Kaiwen Wang, Daeyeon Lee

This research investigates the selective and tunable interactions between polymers and porous solids to enhance polymer upcycling, with two main branches. The first branch focuses on polymer separation and selective catalysis by tuning the surface properties of porous solids to selectively interact with specific polymers in a blend. By allowing only one polymer to penetrate the pores, we achieve solvent-free polymer separation and selective catalysis. We model this process using thin films (hundreds of nm) through capillary rise infiltration and characterize the results using ellipsometry and FTIR. Additionally, we are working to scale these findings in bulk systems (tens of mm) to extend their application in larger-scale processes. The second branch focuses on studying gas solubility in bulk polymers and the effects of polymer confinement on gas diffusion and barrier properties. We use a custom-built quartz crystal microbalance (QCM) apparatus to measure the mass changes in thin films exposed to various gases, allowing us to calculate solubility and diffusion rates under different pressures. The confined polymer films are produced through capillary rise infiltration (CaRI), providing insights into how confinement affects gas solubility and diffusion during catalytic processes. Together, these two branches aim to improve the efficiency of polymer recycling by enabling selective polymer separation and advancing the understanding of polymer-gas interactions in confined environments. This research has the potential to contribute to the development of new, sustainable polymer upcycling technologies, making polymer recycling more feasible and profitable. 

31. Non-monotonic Impact of Random Copolymer Composition on the Kinetics of Capillary Rise Infiltration

Taeyoung Heo, Robert A Riggleman, Daeyeon Lee

Capillary rise infiltration (CaRI) has recently emerged as a versatile technique for fabricating highly filled polymer nanocomposite films with extremely high nanoparticle fractions. Most previous studies on CaRI have focused homopolymers to investigate the influence of confinement on infiltration kinetics and the mechanical properties of resulting composite films. In this study, we investigate the CaRI involving random copolymer infiltrating random packings of silica nanoparticles using in situ ellipsometry. To examine the effect of varying degrees of polymer-silica surface interactions, we use poly(styrene-co-2-vinylpyridine) (S-co-2VP) random copolymers with different ratio of the two monomers: strongly interacting, 2VP and weakly interacting, S. We observe that these random copolymers exhibit significantly slower infiltration rates compared to PS and P2VP homopolymers of the same molecular weight. We believe that the conformation of surface-bound polymers including tails and loops and the enhanced entanglements of chains near the surface may be responsible for the observed trends.

32. Liquid Crystals in Spatially Varying Magnetic Fields with Antagonistic Anchoring

Yvonne Zagzag, Zhe Liu, Chinedum Osuji, Randall Kamien

In the presence of a magnetic field, an LC director can be distorted from a ground state set by a combination of LC elasticity and surface anchoring at any relevant interfaces. Uniform magnetic fields are often used to produce simple LC distortions on demand, but producing more spatially complex distortions is practically challenging. We develop a strategy for the spatially resolved control of the LC director by leveraging field patterns induced by ferromagnetic materials. Patterned magnetic fields are generated from high permeability ferromagnetic microstructures embedded into nematic liquid crystals (NLCs) to manipulate the LC director’s orientation. Each ferromagnetic microstructure produces a unique spatially varying magnetic field. In turn, tuning magnetic field strength in competition with NLC elasticity can pattern a range of spatially complex director configurations. Simulations relate the spatial variation induced in a magnetic field by a ferromagnetic geometry and the resultant director. Our predictive models can inform the inverse design of ferromagnetic microstructures to generate bespoke director patterns. We also link changes in the magnetic field to the migration of elastically driven periodic extinctions in birefringence near the edges of ferromagnetic structures.

33. Antifouling Characteristics of Nanofiltration Membranes Derived from Self-Assembled Mesophases 

Alex Hwang, Chinedum Osuji 

Nanofiltration membranes with uniform and tunable pore sizes are highly sought after as effective materials for wastewater treatment. Macromolecular organics and oily species are prevalent in wastewater streams and are challenging drivers of fouling that lead to decreased membrane performance. Efforts to reduce fouling therefore remain of interest in the development of new nanofiltration membranes. We report that nanostructured thin film composite membranes fabricated from a self-assembled polymerizable surfactant [2-(acryloyloxy)ethyl]dimethyl tetradecyl ammonium bromide (AETDAB) demonstrate excellent fouling resistant to protein solutions and oil-water emulsions. Lyotropic liquid crystal mesophases were cast atop a support membrane, forming cylinders hexagonally-packed cylinders arrayed in the plane of the membrane. The evenly spaced cylinders create channels with diameter of ~1nm that represent the transport limiting dimension for the system. The composite membranes showed outstanding antifouling characteristics, retaining ~95% of permeance over a 72-hour period while completely rejecting the model organic foulant, Bovine Serum Albumin (BSA). The membrane also demonstrated similarly strong fouling resistivity during the filtration of oil-water emulsion, retaining ~95% of permeance. The antifouling characteristic highlights the membrane’s potential to be used for challenging nanofiltration applications, while retaining its performance over long periods of time. 

34. Identifying and Characterizing Protein Surface Hydrophilicity for Non-Fouling Surface Design

Lilia Escobedo, Nick Rego, Amish Patel, Daeyeon Lee

Biofouling, the undesired formation of biofilms, can contaminate a wide variety of surfaces that operate in aqueous environments, such as medical device implants and water filtration membranes. One way to combat this issue is to increase a surface’s hydration to prevent proteins from adsorbing onto the surface, which is the first step in biofilm formation. These “non-fouling” surfaces are often made with homogenous coatings of polar and/or zwitterionic moieties, but eventually succumb to fouling over time. However, recent approaches that coat the surface with amphiphilic moieties suggest that incorporating heterogeneity into the surface design enhances surface hydration. To better understand the role of heterogeneity in non-fouling surface design we seek inspiration from proteins, whose surfaces have evolved to resist non-specific aggregation and fouling by other proteins in the crowded cellular environment. By identifying and characterizing the most hydrophilic regions on protein surfaces, we aim to uncover the chemical patterns responsible for protein-protein selectivity and provide a basis for the creation of non-fouling surfaces. Using specialized molecular dynamics simulations, we have characterized the atomic-level hydrophilicity of a protein surface directly based on water affinity. Using this characterization, we have determined that while hydrophilic and hydrophobic surface atoms contain both polar and nonpolar atoms, charged moieties are predominantly hydrophilic. In fact, we have developed a classification algorithm that can distinguish between hydrophilic and hydrophobic atoms based on proximity to these atoms, suggesting that these atoms behave like hydrophilic centers that influence the hydrophilicity of surrounding atoms. Our results indicate that protein surface hydrophilicity is not only context-dependent but also must be interpreted at the atomic level. From this analysis, we have developed design rules for the composition and chemical patterning of protein-inspired hydrophilic surfaces.  

1. Tuning Nanoparticle Adsorption via Molecular Weight of Polymer Brushes

Katie Sun, Ye Chan Kim, Russell J. Composto, and Karen I. Winey

Stimuli-responsive polyelectrolyte brushes are a promising tool for adsorption-based separation technologies, as environmental changes can modulate the selectivity of the adsorption of molecules and nanoparticles (NPs). Understanding the role of brush architecture is key to optimizing brush performance.1 Low-grafting density brushes are particularly useful for post-fabrication modification, such as for conjugation platforms2 or biosensors.3 In contrast, high grafting density brushes can function as entropic barriers that either prevent4-5 or promote adsorption, making them ideal for applications like anti-fouling coatings or membrane filtration. In this lightning talk, I will explore how varying environmental pH and brush molecular weight (10 and 53 kg/mol) influences the kinetics and selectivity of spherical citrate-coated gold nanoparticle (AuNP) adsorption. I monitored the adsorption of 10- and 20-nm citrate-coated AuNP solutions, with trends elaborated upon in my poster. These findings provide new insights into how nanoscale structural modifications in polymer brushes affect their stimuli-responsive adsorption properties, with implications for designing more efficient separation technologies.

References:

(1) Coad, B. R., et al. ACS Applied Materials & Interfaces 2012, 4.5, 2811-2823.

(2) Schüwer, N.; Geue, T.; Hinestrosa, J. P.; Klok, H.A. Macromolecules 2011, 44, 6868– 6874

(3) Ma, H. W.; He, J. A.; Liu, X.; Gan, J. H.; Jin, G.; Zhou, J. H. ACS Appl. Mater. Interfaces 2010, 2, 3223– 3230

(4) Raynor, J. E.; Capadona, J. R.; Collard, D. M.; Petrie, T. A.; Garcia, A. J. Biointerphases 2009, 4, FA3– FA16

(5)  Lai, B. F. L.; Creagh, A. L.; Janzen, J.; Haynes, C. A.; Brooks, D. E.; Kizhakkedathu, J. N. Biomaterials 2010, 31, 6710– 6718

2. Engineering split Cas13bt3 for inducible RNA editing

Devin Golla, Sherry Gao

Since their discovery, CRISPR-Cas13 ribonucleases have been extensively studied for their ability to programmably target and cleave RNA, a property which will play a key role in the development of precision therapeutics that can modulate gene expression.  The recent emergence of Cas13bt3, a compact Cas13 nuclease which can be delivered using a single AAV vector, represents a promising new platform for precise RNA editing.  However, Cas13bt3’s catalytic domains also engage in non-specific collateral RNA  cleavage, potentially causing damage to the transcriptome and precluding its application in therapeutic contexts. Our current work aims to construct a viable ‘split’ Cas13bt3, in which two separate domains are designed to re-assemble into a functional nuclease upon induction by rapamycin, which can then selectively knockout the expression of target genes. We hypothesize that our choice of an optimal split site near the catalytic domain will both maximize the inducible on-target efficiency of our re-assembled construct, and minimize the amount of collateral cleavage by disrupting the interfaces where nonspecific RNA binding is likely to occur. Currently, we are validating a set of chosen split sites in these Cas13bt3 constructs, and have demonstrated that several split sites enable successful re-assembly and on-target cleavage of an EGFP reporter mRNA, with lower collateral cleavage of a co-expressed mCherry reporter mRNA than the intact Cas13bt3. Going forward, we hope to demonstrate our most promising split  Cas13bt3’s ability to inducibly and selectively cleave endogenous gene targets in human cell lines, and are interested in demonstrating our system’s application to a disease model where a short-term correction of the expression level of a selected RNA  could provide a potential therapeutic benefit.

3. Harnessing Geothermal Energy for Carbon Dioxide Removal: An Integrated Direct Air Capture and Indirect Carbonation Process

Shrey Patel, Maxwell Pisciotta, Jennifer Wilcox

In this study, we propose a renewable carbon dioxide removal (CDR) process that integrates  Direct Air Capture (DAC) and Indirect Carbonation (IDC), both powered by geothermal energy. The process is designed to capture and permanently store 0.25 million tonnes of CO2  annually, utilizing geothermal brine to meet the heat requirements of DAC while also generating electricity through an Organic Rankine Cycle (ORC). This dual use of geothermal energy significantly improves its carbon abatement potential compared to its traditional application for green electricity generation, where energy conversion efficiency is typically low  (~12%). The integration of DAC with IDC offers a full carbon removal pathway. In the IDC step, we utilize mine tailing waste from ultramafic rock mines (like magnesium-rich Twin Sisters Olivine) to sequester the captured CO2 as magnesium carbonate, providing a sustainable and permanent storage solution with potential industrial applications. ASPEN Plus simulations were used to model the process and optimize the heat utilization and electricity production.  Additionally, a sensitivity analysis was conducted to understand how changes in the energy requirements of DAC+IDC affect the production of geothermal electricity and thus, the dependence on external electricity (sourced from on-site Solar facility) and the total land requirements. This study highlights the potential for regions with abundant and accessible geothermal resources to implement a sustainable carbon removal solution. By using renewable geothermal energy to power both DAC and IDC, we provide a scalable option for reducing atmospheric  CO2 levels. Although the CO2 abatement potential is improved, large-scale deployment of such technology depends significantly on factors like creation of a robust supply chain ecosystem, energy security, community acceptance, and socio-economic incentives. This work could serve as a guide for industries and nations looking to develop complete carbon removal infrastructure utilizing low-carbon heat and electricity resources.

4. Deciphering Multimerization Strategies for Controlling Liquid-Liquid Phase Separation with Coiled Coils in IDR-Based Membraneless Organelles

Zhihui Su, Daniel Hammer, Matt Good

In Eukaryotic cells, proteins can undergo natural self assembly and phase separate to form membraneless organelles such as nucleoli, Cajal bodies, P-bodies, and stress granules. Proteins with intrinsically disordered domains (IDRs) can proficiently undergo liquid-liquid phase separation (LLPS) to form condensates that regulate many biological functions. Due to their potential for subcellular compartmentalization and channel-less cargo recruitment and release, membraneless organelles made from LLPS can be excellent bio-building blocks and hubs for cellular communication. In bio-engineered cells and protocells, membraneless organelles offer a brand new alternative platform for cellular functions and expand strategies to facilitate enzymatic communications. Numerous weak interactions between the IDR polypeptides work together to overcome the entropic energy and interfacial free energy costs to create a phase boundary. Higher ordered targeted multimerization of the IDR polypeptides provides fine tuned control for critical concentration and condensate volume. Previously, we demonstrated noncovalent strategies to dimerize two individual IDRs, the LAF-1 RGG domains, to form condensation using cognate coiled coil motifs. Here we develop a high order noncovalent protein IDR multimerization system to generate synthetic membraneless organelles with controllable condensate size and critical concentration. First, we show the optimal cognate coiled coil motif binding configuration for RGG domain dimerization and characterize the dimerization orthogonality through the entire NICP set. Second, we introduce higher ordered IDR multimerization by employing more repeats of coiled coil motifs on both the N or C terminus of the RGG domain. Furthermore, we observe increasing the cognate coiled coil repeats on both termini of the RGG domain suppress phase separation and sequentially decrease the critical temperature. This comprehensive study demonstrated a sophisticated and dynamic RGG coiled coil synthetic system offering a tunable approach and generalizable platform for controlling coacervation valency, and has broad applications such as cargo recruitment and cellular enzymatic control in both bio-engineered cells and protocells.

5. Functionalizing Polymerizable Surfactant Mesophases for Organic Solvent Separations

Jack Granite, Chinedum Osuji

Membrane technologies such as nanofiltration hold promise to achieve highly selective separations, reducing energy costs in some cases by a factor of 2–3. Recent developments in nanostructured materials derived from self-assembled systems, such as polymerizable surfactant mesophases (PSMs), have shown great potential for separating large molecules from aqueous media with state-of-the-art permeability and size selectivity because of their monodisperse pore sizes. Currently, PSMs lack tunability in their chemical selectivity, which is crucial for bulk organic solvent separations. My work seeks to develop functionalized PSMs using modular surfactants to independently tune size selectivity, chemical selectivity, and permeability. I have utilized new reagents in Menshutkin reactions to synthesize quaternary ammonium surfactants featuring head groups of increased hydrophobicity and steric hindrance (methyl, ethyl, isopropyl) and am investigating new reaction pathways to create hydrophilic head groups. Small-angle x-ray scattering and polarized optical microscopy indicate that these (or blends of these) new surfactants exhibit hexagonally packed cylindrical and cubic phases, indicating the potential for PSMs to exhibit combined size and chemical selectivity in organic solvent nanofiltration.

6. Encapsulation of Bioactive Compounds in Oil-in-water Microcapsules 

Ekta Jagtiani, Chinedum Osuji

Oil-in-water emulsions are one of the most studied type of dispersions and several applications in food, pharmaceuticals, cosmetics has a common objective of successful encapsulation. Cellulose nanofibers (CNFs) have appeared as potential candidates to stabilize emulsions for their special characteristics, including high aspect ratio and surface area, mechanical strength permitting effective adsorption at the oil-water interface. Among the bioactive compounds used for encapsulation, carvacrol seems to be promising as it is a bioactive compound widely studied for its potential applications in pharmaceutical, nutraceutical and food industries offering numerous health benefits. The stability of such emulsions is largely determined by the oil-to-water ratio, CNF concentration, pH and ionic strength which affect microcapsule size distribution, creaming tendency and stability of overall emulsion. The influence of these factors is interconnected and understanding their interaction is critical while formulating emulsions that are stable at different environmental conditions with desired encapsulation efficiency being the goal. The present study systematically examines the influence of these parameters on CNF-stabilized oil-in-water emulsions properties for encapsulating carvacrol to highlight insights relevant for designing more efficient and stable emulsions for industrial applications.

7. –Abstract Withdrawn–

Hoang Dinh, Daeyeon Lee, Kathleen Stebe

8. Liquid Crystals in Spatially Varying Magnetic Fields with Antagonistic Anchoring

Yvonne Zagzag, Zhe Liu, Chinedum Osuji, Randall Kamien

In the presence of a magnetic field, an LC director can be distorted from a ground state set by a combination of LC elasticity and surface anchoring at any relevant interfaces. Uniform magnetic fields are often used to produce simple LC distortions on demand, but producing more spatially complex distortions is practically challenging. We develop a strategy for the spatially resolved control of the LC director by leveraging field patterns induced by ferromagnetic materials. Patterned magnetic fields are generated from high permeability ferromagnetic microstructures embedded into nematic liquid crystals (NLCs) to manipulate the LC director’s orientation. Each ferromagnetic microstructure produces a unique spatially varying magnetic field. In turn, tuning magnetic field strength in competition with NLC elasticity can pattern a range of spatially complex director configurations. Simulations relate the spatial variation induced in a magnetic field by a ferromagnetic geometry and the resultant director. Our predictive models can inform the inverse design of ferromagnetic microstructures to generate bespoke director patterns. We also link changes in the magnetic field to the migration of elastically driven periodic extinctions in birefringence near the edges of ferromagnetic structures.

9. Lyotropic Liquid Crystal Membranes in Desalination and Water Harvesting

Ahmad Ali, Chinedum Osuji

Water scarcity is a growing global challenge, affecting millions of people and threatening ecosystems, but innovative solutions such as desalination and water harvesting offer promising methods to alleviate this crisis by efficiently converting seawater and atmospheric moisture into potable water. Current desalination membranes face a tradeoff between selectivity and permeability, and mass-producing defect free membranes remains challenging. In the context of water harvesting, current technology lacks advancements in optimizing membrane materials for high-efficiency moisture capture, as well as long-term performance evaluations under varying environmental conditions. I propose a novel approach that circumvents these challenges by utilizing self-assembled hexagonally packed lyotropic liquid crystal mesophase membranes. I will explore the fundamental science governing the impact of pore size and chemistry on desalination and water harvesting performance. Membrane nanostructure and pore size are identified using a combination of Polarized Optical Microscope (POM) and Small Angle Xray Scattering (SAXS). Water harvesting performance is analyzed using sorption analyzer. Understanding the fundamental science governing water harvesting and desalination will allow for the utility of lyotropic liquid crystal mesophase as next generation materials. 

10. Identifying and Characterizing Protein Surface Hydrophilicity for Non-Fouling Surface Design

Lilia Escobedo, Nick Rego, Amish Patel, Daeyeon Lee

Biofouling, the undesired formation of biofilms, can contaminate a wide variety of surfaces that operate in aqueous environments, such as medical device implants and water filtration membranes. One way to combat this issue is to increase a surface’s hydration to prevent proteins from adsorbing onto the surface, which is the first step in biofilm formation. These “non-fouling” surfaces are often made with homogenous coatings of polar and/or zwitterionic moieties, but eventually succumb to fouling over time. However, recent approaches that coat the surface with amphiphilic moieties suggest that incorporating heterogeneity into the surface design enhances surface hydration. To better understand the role of heterogeneity in non-fouling surface design we seek inspiration from proteins, whose surfaces have evolved to resist non-specific aggregation and fouling by other proteins in the crowded cellular environment. By identifying and characterizing the most hydrophilic regions on protein surfaces, we aim to uncover the chemical patterns responsible for protein-protein selectivity and provide a basis for the creation of non-fouling surfaces. Using specialized molecular dynamics simulations, we have characterized the atomic-level hydrophilicity of a protein surface directly based on water affinity. Using this characterization, we have determined that while hydrophilic and hydrophobic surface atoms contain both polar and nonpolar atoms, charged moieties are predominantly hydrophilic. In fact, we have developed a classification algorithm that can distinguish between hydrophilic and hydrophobic atoms based on proximity to these atoms, suggesting that these atoms behave like hydrophilic centers that influence the hydrophilicity of surrounding atoms. Our results indicate that protein surface hydrophilicity is not only context-dependent but also must be interpreted at the atomic level. From this analysis, we have developed design rules for the composition and chemical patterning of protein-inspired hydrophilic surfaces.