Skip to soundbites »

Invited speakers

Lauren Zarzar (Penn State University) (14:05 - 14:35)
Active droplets that swim, chase, and organize
Chemotactic interactions are ubiquitous in nature and can lead to nonreciprocal and complex emergent behavior in multibody systems. However, developing synthetic, inanimate embodiments of a chemomechanical framework for generating nonreciprocal and collective interactions of tunable strength and directionality has been challenging. Emulsions, which are mixtures of immiscible liquids characterized by chemical inhomogeneity and non-equilibrium states, are unique materials in which to study how spatially controlled gradients affect chemical “communication” leading to organized assembly and motion. We present a source-sink framework for rationalizing and predicting micelle-mediated interactions between droplets of different chemistries and explore the ramifications for chemically programmable active fluids. We show how chemotactic signaling between microscale oil droplets of different chemistries in micellar surfactant solutions can result in predator-prey-like nonreciprocal chasing interactions. We also explore the principles guiding the propulsion of Janus oil droplets that are undergoing micelle-mediated solubilization, discussing how the introduction of multiple liquid-liquid interfaces in a droplet governs swimming dynamics. A key conclusion is that for droplets containing both a mobile (solubilizing) and non-mobile oil, the degree of partitioning of the mobile oil across the Janus droplets’ oil-oil interface contributes significantly to the droplet speed and swimming direction. Droplet dynamics can further be affected by interfacially-active materials, such as polymers, capsules, and particles. Our findings demonstrate how chemically-minimal emulsion systems can be designed with controllable chemotactic interactions to generate emergent self-organization and collective behaviors reminiscent of biological systems.
Sara Jabbari Farouji (UvA) (15:20 - 15:45)
Emergent Collective Dynamics in Active Matter with Long-range Interactions
Collectives of autonomous systems such as bacteria, self-propelled colloids worms and birds exhibit emergent collective phenomena, which cannot be understood by extrapolating the behavior of individual constituents. Efforts to unravel the physical principles governing collective dynamics of autonomous systems across all scales have led to the emergence of the field of active matter which is rapidly becoming a key paradigm of out-of-equilibrium soft matter. A central question is if we can understand the emergent collective properties in terms of interplay between self-propulsion and interparticle interactions. Recent activities in our group focus on understanding the role of long-range hydrodynamic, magnetic and chemotactic interactions on the collective dynamics of self-propelled systems. For each case, we will briefly discuss the novel and counterintuitive collective features, which arise because of interplay between long-range interactions and self-propulsion.
Louise Jawerth (UL) (15:45 - 16:10)
Protein condensates as aging Maxwell fluids
There are biological proteins that can phase separate out of solution to form protein-dense droplets similar to how oil will de-mix from water. These so-called protein condensates have been identified in an extremely large range of important biological processes. Increasingly, we find that the exact material nature of the liquid-like condensates (such as their viscosities) is important for proper function in vivo. Interestingly, protein condensates exhibit a range of material properties and behaviors not exhibited by synthetic materials. In this talk, I will discuss our recent discovery of an aging behavior in these materials in which they age from being liquid-like to solid-like. We use a combination of passive and active microrheology along with other tools to characterize this process. We find the protein condensates behave as Maxwell fluids with characteristic relaxation time scales that increase as the condensates age (Jawerth, Science 2020). I will discuss how this aging is both similar and distinct from aging seen in glasses. Finally, I will briefly discuss the myriad material properties that protein condensates exhibit and how this is an exciting, important direction for soft condensed matter generally.
Siddharth Deshpande (WUR) (16:40 - 17:05)
A tale of two droplets
In this talk, I will tell you about two stories that have recently emerged from my lab, each involving a different kind of droplet.

The first story is about a novel and easy way to make biocompatible containers for synthetic cells. Engineering synthetic cells has a broad appeal, from understanding living cells to designing novel biomaterials for therapeutics and hybrid interfaces. We use phase-separated liquid droplets and coat it with actin cytoskeleton, an intracellular protein polymer. Under the right chemical conditions, the droplets are transformed into cell-sized porous containers, which we call actinosomes. We show the functionality of actinosomes by using them as bioreactors capable of protein synthesis. Actinosomes are a handy addition to the synthetic cell platform, with appealing properties like ease-of-production, inherent encapsulation capacity, and an active surface to trigger signalling cascades and form multicellular assemblies, with potential in medical and biotechnological applications.

The second story uses liquid crystal droplets as microsensors capable of sensing amphiphiles. We utilize chiral nematic liquid crystal micro-droplets, which show strongly reflected structural colour, as sensing platforms for surface active agents. We systematically quantify the optical response of closely related biological amphiphiles and find unique optical signatures for each species. We show lab-on-achip capability of our method by drying droplets in high-density two-dimensional arrays and simply hydrating the chip to detect dissolved analytes. Finally, we show proof-of-principle in vivo biosensing in the intestinal tracts of live zebrafish larvae, demonstrating CLC droplets show a clear and differential optical response between healthy and inflamed tissues. Our unique approach has great potential in developing on-site detection platforms and detecting biological amphiphiles in living organisms.

1. K.A. Ganar, L. Leijten, and S. Deshpande. Actinosomes; condensate-templated proteinaceous containers for engineering synthetic cells, bioRxiv, 2021. doi
2. L.W. Honaker, C. Chen, F.M.H. Dautzenberg, S. Brugman, and S. Deshpande. Designing biological micro-sensors with chiral nematic liquid crystal droplets, bioRxiv, 2021. biorxiv.org


The first 10 soundbites are planned in the first session (Demirörs - Ibis) and the remaining 14 (Brouwer - Parnell) take place in the second session.

Ahmet Demirörs from ETH Zurich:
Amphibious Transport of Fluids and Solids by Soft Magnetic Carpets
Alberto Pérez de Alba Ortíz from Utrecht University:
Inverse design of free-energy landscapes for colloidal self-assembly
Alexander Barnaveli from UU:
To be decided
Andrea Giuntoli from Zernike Institute, University of Groningen:
Predicting materials properties in 1 picosecond
David Dykstra from University of Amsterdam:
Oligomodal Mechanical Metamaterials
Dimitrios Krommydas from Institute Lorentz, Leiden university:
Backlow effects in p-atic liquid crystals
Fabrizio Camerin from Utrecht University:
Depletion-induced crystallization of anisotropic colloids
Farnoosh Joulaeian from Institute for Advanced Studies in Basic Sciences:
Studying the dynamics of Chlamydomonas under polarized light illuminations
Jayant Pande from BarIlan University, Israel:
Beyond R0; an analytical expression for the true chance of invasion of an invasive strain
Fatma IBIS from TU Delft:
Nucleation kinetics of calcium oxalate monohydrate as a function of pH, magnesium, and osteopontin concentration quantified with droplet microfluidics
Kelly Brouwer from Utrecht University:
BINARY SUPRAPARTICLES; Self-assembly of nanoparticles for heterogeneous catalysis
Ludwig Hoffmann from Leiden U:
Deformation Dynamics of Active Shells; Polar v Nematic
Luisa Orozco from University of Liège:
What if Archimedes had done his tests in granular fluidized beds?
Marjolein de Jager from Utrecht University:
Crystal nucleation of hard-core Yukawa particles
Martijn van Galen from Wageningen University:
Catching up on Nature; Designing a Synthetic Catch Bond
Mohammad Shoaib from University of Toronto:
To be decided
Patrizio Raffa from University of Groningen:
Research at RaffaLab on amphiphilic polymers
Roy Hoitink from Soft Condensed Matter and Biophysics, Utrecht University:
Towards real-space analysis of supraparticles with five-fold symmetry
Salma Ismaili from Utrecht University:
A theory for the twist-splay-bend nematic phase of banana-shaped colloidal particles
Vincent Debets from Eindhoven University of Technology:
Cage Length Controls the Non-Monotonic Dynamics of Active Glassy Matter
Willem Gispen from Utrecht University:
Crystal nucleation kinetic phase diagram of charged colloids
Yibo Chen from Physics of Fluids, University of Twente:
Buoyancy-driven attraction of diffusiophoretic particles
Zohreh Farmani from Wageningen University and Research:
High contrast MRI of soft materials to study shear band evolution
Steven Parnell from TU Delft:
Small Angle Neutron Scattering in Delft