Influence of the glycocalyx on the size and mechanical properties of plasma membrane-derived vesicles.

Recent studies have reported that the overexpression of MUC1 glycoproteins on cell surfaces changes the morphology of cell plasma membranes and increases the blebbing of vesicles from them, supporting the hypothesis that entropic forces exerted by MUC1 change the spontaneous curvature of cell membranes. However, how MUC1 is incorporated into and influences the size and biophysical properties of plasma-membrane-blebbed vesicles is not understood. Here we report single-vesicle-level characterization of giant plasma membrane vesicles (GPMVs) derived from cells overexpressing MUC1, revealing a 40× variation in MUC1 density between GPMVs from a single preparation and a strong correlation between GPMV size and MUC1 density.

Design of Chemoresponsive Liquid Crystals Using Metal-Coordinating Polymer Surfaces.

Liquid crystals (LCs), when interfaced with chemically functionalized surfaces, can amplify a range of chemical and physical transformations into optical outputs. While metal cation-binding sites on surfaces have been shown to provide a basis for the design of chemoresponsive LCs, the cations have been found to dissociate from the surfaces and dissolve slowly into LCs, resulting in time-dependent changes in the properties of LC-solid interfaces (which impacts the reliability of devices incorporating such surfaces). Here, we explore the use of surfaces comprising metal-coordinating polymers to minimize the dissolution of metal cations into LCs and characterize the impact of the interfacial environment created by the coordinating polymer on the ordering and time-dependent properties of LCs.

Single-step synthesis of shaped polymeric particles using initiated chemical vapor deposition in liquid crystals.

We elucidate a previously unknown synthesis pathway that leads to polymeric nanospheres, orientation-controlled microgels, or microspheroids via single-step polymerization of divinylbenzene (DVB) using initiated chemical vapor deposition (iCVD) in liquid crystals (LC). iCVD supplies vapor-phase reactants continuously, avoiding the critical limitation of reactant-induced disruption of LC structure that has plagued past LC-templated polymerization processes. LC is leveraged as a real-time display of the polymerization conditions and particle emergence, captured using an in situ long-focal range microscope.

Electronically configurable microscopic metasheet robots.

Shape morphing is vital to locomotion in microscopic organisms but has been challenging to achieve in sub-millimetre robots. By overcoming obstacles associated with miniaturization, we demonstrate microscopic electronically configurable morphing metasheet robots. These metabots expand locally using a kirigami structure spanning five decades in length, from 10 nm electrochemically actuated hinges to 100 μm splaying panels making up the ~1 mm robot.

Command of three-dimensional solitary waves via photopatterning.

Multidimensional solitons are prevalent in numerous research fields. In orientationally ordered soft matter system, three-dimensional director solitons exemplify the localized distortion of molecular orientation. However, their precise manipulation remains challenging due to unpredictable and uncontrolled generation.

Generation and Propagation of Flexoelectricity-Induced Solitons in Nematic Liquid Crystals.

Solitons in nematic liquid crystals facilitate the rapid transport and sensing in microfluidic systems. Little is known about the elementary conditions needed to create solitons in nematic materials. In this study, we apply a combination of theory, computational simulations, and experiments to examine the formation and propagation of solitary waves, or "solitons", in nematic liquid crystals under the influence of an alternating current (AC) electric field.

Self-Timed and Spatially Targeted Delivery of Chemical Cargo by Motile Liquid Crystal.

A key challenge underlying the design of miniature machines is encoding materials with time- and space-specific functional behaviors that require little human intervention. Dissipative processes that drive materials beyond equilibrium and evolve continuously with time and location represent one promising strategy to achieve such complex functions. This work reports how internal nonequilibrium states of liquid crystal (LC) emulsion droplets undergoing chemotaxis can be used to time the delivery of a chemical agent to a targeted location.

Actuating Liquid Crystals Rapidly and Reversibly by Using Chemical Catalysis.

Microtubules and catalytic motor proteins underlie the microscale actuation of living materials, and they have been used in reconstituted systems to harness chemical energy to drive new states of organization of soft matter (e.g., liquid crystals (LCs)).

Minimal Model of Solitons in Nematic Liquid Crystals.

Solitons in liquid crystals have generated considerable interest. Several hypotheses of varying complexity have been advanced to explain how they arise, but consensus has not emerged yet about the underlying forces responsible for their formation or their structure. In this work, we present a minimal model for solitons in achiral nematic liquid crystals, which reveals the key requirements needed to generate them in the absence of added charges.

Elucidating Molecular-Scale Principles Governing the Anchoring of Liquid Crystal Mixtures on Solid Surfaces.

Computational chemistry calculations are broadly useful for guiding the atom-scale design of hard-soft material interfaces including how molecular interactions of single-component liquid crystals (LCs) at inorganic surfaces lead to preferred orientations of the LC far from the surface. The majority of LCs, however, are not single-component phases but comprise of mixtures, such as a mixture of mesogens, added to provide additional functions such as responsiveness to the presence of targeted organic compounds (for chemical sensing). In such LC mixtures, little is understood about the near-surface composition and organization of molecules and how that organization propagates into the far-field LC orientation.

Jetting and Droplet Formation Driven by Interfacial Electrohydrodynamic Effects Mediated by Solitons in Liquid Crystals.

Solitons are highly confined, propagating waves that arise from nonlinear feedback in natural (e.g., shallow and confined waters) and engineered systems (e.

Self-Assembly of Peptide-Conjugated Forklike Mesogens at Aqueous/Liquid Crystalline Interfaces: Molecular Design for Ordering Transition Induced by Specific Binding of Biomolecules.

Self-assembly of functional liquid crystals provides a powerful approach to the development of stimuli-responsive materials and interfaces. Here, we have designed and synthesized bioconjugated amphiphilic dendritic mesogens containing arginine-glycine-aspartic acid (RGD) peptide sequence to develop new biofunctional aqueous/liquid crystalline interfaces. We have found that the RGD peptide-conjugated forklike mesogens induce the homeotropic alignment of liquid crystals at the aqueous interfaces, leading to distinct optical changes caused by the specific binding of the target proteins.

Energy landscapes on polymerized liquid crystal interfaces.

We measure and model monolayers of concentrated diffusing colloidal probes interacting with polymerized liquid crystal (PLC) planar surfaces. At topological defects in local nematic director profiles at PLC surfaces, we observe time-averaged two-dimensional particle density profiles of diffusing colloidal probes that closely correlate with spatial variations in PLC optical properties. An inverse Monte Carlo analysis of particle concentration profiles yields two-dimensional PLC interfacial energy landscapes on the -scale, which is the inherent scale of many interfacial phenomena (, self-assembly, adsorption, diffusion).

Gas-phase microactuation using kinetically controlled surface states of ultrathin catalytic sheets.

Biological systems convert chemical energy into mechanical work by using protein catalysts that assume kinetically controlled conformational states. Synthetic chemomechanical systems using chemical catalysis have been reported, but they are slow, require high temperatures to operate, or indirectly perform work by harnessing reaction products in liquids (e.g.

Liquid Crystals as Multifunctional Interfaces for Trapping and Characterizing Colloidal Microplastics.

Identifying and removing microplastics (MPs) from the environment is a global challenge. This study explores how the colloidal fraction of MPs assemble into distinct 2D patterns at aqueous interfaces of liquid crystal (LC) films with the goal of developing surface-sensitive methods for identifying MPs. Polyethylene (PE) and polystyrene (PS) microparticles are measured to exhibit distinct aggregation patterns, with addition of anionic surfactant amplifying differences in PS/PE aggregation patterns: PS changes from a linear chain-like morphology to a singly dispersed state with increasing surfactant concentration whereas PE forms dense clusters at all surfactant concentrations.

Non-equilibrium ordering of liquid crystalline (LC) films driven by external gradients in surfactant concentration.

Hypothesis: Gradients in the concentration of amphiphiles play an important role in many non-equilibrium processes involving complex fluids. Here we explore if non-equilibrium interfacial behaviors of thermotropic (oily) liquid crystals (LCs) can amplify microscopic gradients in surfactant concentration into macroscopic optical signals.

Experiments: We use a milli-fluidic system to generate gradients in aqueous sodium dodecyl sulfate (SDS) concentration and optically quantify the dynamic ordering of micrometer-thick nematic LC films that contact the gradients.

Optical Fingerprinting of Dynamic Interfacial Reaction Pathways Using Liquid Crystals.

Reactions at interfaces between fluid phases are widely used to synthesize small molecules, polymers, and nanoparticles. monitoring of the underlying dynamic reaction pathways remains challenging. Liquid crystals (LCs) have been used to detect simple chemical transformations at interfaces in situations where interface-bound reactants and products trigger distinct equilibrium orientations of LCs.

Interactions of SARS-CoV-2 and MERS-CoV fusion peptides measured using single-molecule force methods.

We address the challenge of understanding how hydrophobic interactions are encoded by fusion peptide (FP) sequences within coronavirus (CoV) spike proteins. Within the FPs of severe acute respiratory syndrome CoV 2 and Middle East respiratory syndrome CoV (MERS-CoV), a largely conserved peptide sequence called FP1 (SFIEDLLFNK and SAIEDLLFDK in SARS-2 and MERS, respectively) has been proposed to play a key role in encoding hydrophobic interactions that drive viral-host cell membrane fusion. Although a non-polar triad (Leu-Leu-Phe (LLF)) is common to both FP1 sequences, and thought to dominate the encoding of hydrophobic interactions, FP1 from SARS-2 and MERS differ in two residues (Phe 2 versus Ala 2 and Asn 9 versus Asp 9, respectively).

Using Nanoscopic Solvent Defects for the Spatial and Temporal Manipulation of Single Assemblies of Molecules.

Here we report the use of defects in ordered solvents to form, manipulate, and characterize individual molecular assemblies of either small-molecule amphiphiles or polymers. The approach exploits nanoscopic control of the structure of nematic solvents (achieved by the introduction of topological defects) to trigger the formation of molecular assemblies and the subsequent manipulation of defects using electric fields. We show that molecular assemblies formed in solvent defects slow defect motion in the presence of an electric field and that time-of-flight measurements correlate with assembly size, suggesting methods for the characterization of single assemblies of molecules.

Two-Dimensional Mechanics of Atomically Thin Solids on Water.

Movement of a three-dimensional solid at an air-water interface is strongly influenced by the extrinsic interactions between the solid and the water. The finite thickness and volume of a moving solid causes capillary interactions and water-induced drag. In this Letter, we report the fabrication and dynamical imaging of freely floating MoS solids on water, which minimizes such extrinsic effects.

Ordering Transitions of Liquid Crystals Triggered by Metal Oxide-catalyzed Reactions of Sulfur Oxide Species.

Liquid crystals (LCs), when supported on reactive surfaces, undergo changes in ordering that can propagate over distances of micrometers, thus providing a general and facile mechanism to amplify atomic-scale transformations on surfaces into the optical scale. While reactions on organic and metal substrates have been coupled to LC-ordering transitions, metal oxide substrates, which offer unique catalytic activities for reactions involving atmospherically important chemical species such as oxidized sulfur species, have not been explored. Here, we investigate this opportunity by designing LCs that contain 4'-cyanobiphenyl-4-carboxylic acid (CBCA) and respond to surface reactions triggered by parts-per-billion concentrations of SO gas on anatase (101) substrates.

Sensing Gas Mixtures by Analyzing the Spatiotemporal Optical Responses of Liquid Crystals Using 3D Convolutional Neural Networks.

We report how analysis of the spatial and temporal optical responses of liquid crystal (LC) films to targeted gases, when performed using a machine learning methodology, can advance the sensing of gas mixtures and provide important insights into the physical processes that underlie the sensor response. We develop the methodology using O and Cl mixtures (representative of an important class of analytes) and LCs supported on metal perchlorate-decorated surfaces as a model system. Although O and Cl both diffuse through LC films and undergo redox reactions with the supporting metal perchlorate surfaces to generate similar initial and final optical states of the LCs, we show that a three-dimensional convolutional neural network can extract feature information that is encoded in the spatiotemporal color patterns of the LCs to detect the presence of both O and Cl species in mixtures and to quantify their concentrations.

Formation of versus Recruitment to RNA-Rich Condensates: Controlling Effects Exerted by Peptide Side Chain Identity.

Liquid-liquid phase separation (LLPS), the spontaneous formation of contiguous liquid phases with distinct compositions, has been long known in chemical systems and more recently recognized as a ubiquitous feature of cell biology. We describe a system involving biologically relevant components, synthetic peptides, and total yeast RNA, that has enabled us to explore factors that underlie phase separation. Coulombic complementarity between a cationic peptide and anionic RNA is necessary but not sufficient for formation of a condensed phase in our system.

Programming Solitons in Liquid Crystals Using Surface Chemistry.

AC electric fields cause three-dimensional orientational fluctuations (solitons) to form and rapidly propagate in confined films of liquid crystals (LCs), offering the basis of a new class of active soft matter (e.g., for accelerating mixing and transport processes in microscale chemical systems).

Stimuli-Responsive Liquid Crystal Printheads for Spatial and Temporal Control of Polymerization.

Polymerization reactions triggered by stimuli play a pivotal role in materials science, with applications ranging from lithography to biomedicine to adaptive materials. However, the development of chemically triggered, stimuli-responsive systems that can confer spatial and temporal control on polymerization remains a challenge. Herein, chemical-stimuli-induced polymerization based on a liquid crystal (LC) printhead is presented.