Conveners
Soft Matter Canada 2018 | Matière molle Canada 2018
- Andrew Rutenberg (Dalhousie University)
Description
A satellite meeting to the CAP Congress that will consist of a full day of events including talks and networking time, with a focus on supporting the network of Canadian physicists working in soft matter, which includes people working with polymers, colloids, and bio-inspired systems.
Traditionally, the wetting of a solid surface by the drop of an emulsion has been thought to be mediated by the formation of a liquid bridge that connects the drop and the surface. In the current work, we experimentally show the spreading of a drop on a surface follows a different, new mechanism. Experiments were conducted for liquid-liquid systems, wherein drops of higher density (glycerol)...
In a crowded space, a long chain molecule can be phase-separated into a condensed state, redistributing the surrounding crowders. Here we discuss how crowding influences the spatial organization of a ring polymer, consisting of two “arms," in a cylindrical space. In a parameter space of biological relevance, the distributions of monomers and crowders follow a simple relationship: the sum of...
The internal structure of porous materials and membranes plays a critical role in their mechanical and biochemical properties, especially if they are targeted for cell growth in tissue healing and regeneration applications. Collagenous membranes are a class of proteinaceous materials that has been targeted for cell scaffolding studies because collagen is a structural protein found in many...
MacSANS is a new small angle neutron scattering (SANS) beamline currently under construction at the McMaster Nuclear Reactor, a 5 MW research reactor based at McMaster University in Hamilton, Ontario. This beamline is designed to study a broad range of nanostructured materials, including biological membranes, polymers, superconductors, and novel magnets. In particular, MacSANS will allow...
We study the structure of novel polymers for proton and anion exchange membranes through a combination of experiment and simulations. X-ray and neutron scattering experiments reveal microphase separation and intermolecular order, and interpretation is validated by molecular dynamics (MD) simulations. These studies help us understand the conductivity and swelling of the materials, and inform...
Living cells are composed of a complex mixture of macromolecules. To regulate their activity, cells partition these molecules into specialized compartments called organelles. Typically, membranes form a selective barrier between organelles and the cytoplasm, allowing each compartment to maintain a distinct biochemical composition that is tailored to its function. However, cells also contain a...
Ideally, we would like to have first-principles simulations capable of quantitatively accurate predictions for any block copolymer system. Usually, our choice of model involves balancing the complexity needed to faithfully represent an actual experimental system and the simplicity required to make the simulation tractable. Fortunately, block copolymer phase behavior is believed to become...
Biomaterial fabrics have numerous biomedical applications ranging from drug delivery to tissue engineering. A variety of approaches are available for generating biomaterial fibers from various precursor polymer solutions. Approaches such as wet-spinning, electrospinning, and extrusion have been exploited in the past to generate extremely long fibers ranging in diameter from tens of nanometers...
Collagen is the protein building block of most mammalian tissues such as tendon, arteries, skin and bone. In its triple helical form, collagen assembles into fibrils with tensile properties comparable to the strongest man-made polymer materials. Structural characterization of collagen fibrils using X-ray scattering and electron microscopy led to a picture where long triple helices form a...
The extracellular matrix (ECM), a complex network of proteins including collagen (COL) and fibronectin (FN) couples a cell with its environment and directly regulates the cell’s fate via physical and biochemical signals. Although the ECM was often considered a static structure providing cohesion and mechanical integrity to tissues, it has recently been shown that (i) the nano-structure, (ii)...
Amphiphilic secondary structures are ubiquitous in native proteins, where they serve a wide variety of functions from specific binding ligands to structural elements in supramolecular assemblies. This talk describes the use of amphiphilic coiled-coil motifs in modular protein polymers as a strategy to achieve electrochemical gelation capabilities. Our de novo electrogelation protein is a...
Hydrophobins are low molecular weight (5-20 kDa) self-assembling proteins secreted by fungi that accumulate at hydrophobic-hydrophilic interfaces and are extremely surface-active. Hydrophobins can also undergo a structural rearrangement and oligomerize to form rodlets, which are an insoluble functional amyloid that coats fungal spores to act as a water repellent, facilitate dispersal into the...
Monte Carlo simulations are used to study the conformational properties of a folded semiflexible polymer confined to a long channel. We measure the variation in the conformational free energy with respect to the end-to-end distance of the polymer, and from these functions we extract the free energy of the hairpin fold as well as the entropic force arising from interactions between the portions...
Natural and engineered proteins have recently been discovered with a unique ability to reversibly switch between entirely different 3-dimensional structures, with accompanying major changes in their secondary structure contents, hydrophobic sidechain packing and overall shape. The major conformational changes in these shape-shifting proteins are triggered by, for example, ligand binding,...
Water is the most important solvent in biological systems. Yet majority of its properties are poorly reproduced by the most commonly used models. An ideal water model needs to accurately capture both structure and dynamics over a wide range of thermodynamic conditions.
To create such a model we attempted both coarse grained1 and atomistic parametrizations. Our experience shows the...
Introduction: The three-dimensional (3D) culture of neural cells in extracellular matrix (ECM) gels holds promise for modeling neurodegenerative diseases. However, air-liquid interfacial tension and evaporation can result in inconsistent 3D cultures at low volumes. Thick-layer hydrogels can counter these factors, but large diffusion distances, high cost, and incompatibility with standard...
The production of functional skin equivalents derived from human cells holds promise for reconstruction of severe wounds and for modeling various skin pathologies. Although epidermal cells have the capacity to self-organize and form stratified structures in culture, it is often difficult to integrate these structures with dermal components. In recent years, cellular bioprinting has emerged as...
The collagen fibrils are the main building block of connective tissues in mammals where they fulfill both structural and mechanical roles. The structure of a fibril is based on collagen molecules that self-assemble into micro-fibrils and sub-fibrils stabilized by hydrogen bonds and covalent crosslinks. The non-integer staggering of collagen molecules results in a characteristic D-band pattern...
Many biologically motivated problems naturally call for the investigation and comparison of molecular variants, such as determining the mechanisms of specificity in biomolecular interactions or the mechanisms of molecular evolution. We consider a generalized ensemble algorithm for coarse-grained simulations of biomolecules which allows the thermodynamic behavior of two or more sequences to be...
We explore a variety of thermodynamically stable molecular configurations of collagen fibrils. Using a liquid crystal model of radial fibril structure with a double-twist director field, we show that two dimensionless parameters, the ratio of saddle-splay to twist elastic constants $ k_{24}/K_{22}$ and the ratio of surface tension to chiral strength $\tilde{\gamma} \equiv \gamma/(K_{22}q)$,...
