- Published on 16 October 2018
Physicists develop a model to explain how deforming a helix could generate additional locomotion for some microorganisms and mini-robots
Many microorganisms rely on helices to move. For example, some bacteria rotate a helical tail, called a flagellar filament, for thrust and deform these tails during rotation. In addition, some types of bacteria, named Spirochaetes, rely on the deformation of a helical body for their motion. To better understand such locomotion mechanisms, scientists have created mathematical models of mini-robots with helical structures, referred to as swimmers. In a recent study published in EPJ E, Lyndon Koens from the University of Cambridge, UK, and colleagues, identify the factors enhancing the agility of deforming helix swimmers.
EPJ E Highlight - How lactoferrin clamps down on free roaming iron ions to stop nefarious effects on cells
- Published on 20 September 2018
New study elucidates structure of the protein lactoferrin as it undergoes transition from an open to a closed structure to decrease the level of free iron ions in the body
What prevents our cells from being overexposed to iron ions roaming freely in the body is a protein called lactoferrin, known for its ability to bind tightly to such ions. These free ions are essential for a number of biological processes. If found in excessive quantities, however, they could cause damage to proteins and DNA in the body, sometimes even leading to cell death. This is because free iron ions lead to an increase of the concentration of reactive substances with oxidising power roaming freely in the body. This has driven scientists to develop a better understanding of how lactoferrin's structural change helps to clamp down on free iron ions. In a new study published in EPJ E, Lilia Anghel from the Institute of Chemistry in Chisinau, Republic of Moldova, and research collaborators study the changes in the structure of lactoferrin as it binds to iron ions, using combined experimental and molecular dynamics simulations.
- Published on 18 September 2018
New study demonstrates adsorption of chemotherapy drugs onto active carbon delivery capsule can be enhanced with aluminium atom inclusions
The efficacy of chemotherapy treatment depends on how effectively it reaches cancerous cells. Increasing targeted delivery could mean decreasing side effects. Scientists are enhancing methods of selectively transmitting active chemotherapy agents and reducing their toxicity by encapsulating chemo drugs into active carbon used as the targeted delivery device. In a new study published in EPJ E, Gabriel Román, from the National University of the South, in Bahia Blanca, Argentina, and colleagues have demonstrated that adding minute amounts of aluminium atoms onto activated carbon atoms helps increase the adsorption onto the delivery carbon capsule of a standard chemotherapy drug, called 5-Fluorouracil (5-FU). This drug is typically used for stomach, colorectal, neck and head cancer treatments. This model could lead to more effective and convenient cancer treatments with fewer side effects by encapsulating the chemo drug into the active carbon, so that it can be taken orally.
EPJE Colloquium – Theories that help us understand self-assembling soft matter with strong interacting groups
- Published on 12 September 2018
Amphiphilic molecules contain both hydrophilic and lipophilic moieties. When in solution they produce structures coming from cooperative interactions of many functional units acting in synergy. Most self-assembling soft matter systems involve strong specific interactions of functional units leading to qualitatively new structures of highly soluble micellar or fibrillar aggregates. In this EPJ E Colloquium, Nyrkova and Semenov focus on the systems with the incorporated into unimer molecules and discuss the effects of packing frustrations and unimer chirality as well as the origins of spontaneous morphological chirality in the case of achiral unimers. They describe several theoretical approaches (overcoming the limitations of weak interaction models) including the concepts of super-strong segregation, geometrical mismatch and orientational frustration. They also review some recently developed phenomenological theories of surfactant membranes and multiscale hierarchical approaches based on all-atomic modeling of packing structures of amphiphilic molecules with strongly interacting groups.
- Published on 31 August 2018
In this EPJ E Topical Review, Armando Maestro and colleagues unravel the physico-chemical bases underlying the attachment of particles to fluid interfaces. Their focus is on the relaxation mechanisms involved in the equilibration of particle-laden interfaces.
Particle-laden interfaces play a key role in many systems that are used in industrial and technological applications, such as the stabilization of foams, emulsions, or thin films, flotation processes, encapsulation, pharmaceutical formulations, food technology and catalysis.
- Published on 22 August 2018
The drying of complex solutions, such as colloidal dispersions, is a phenomenon of great interest, both scientific and technical, ranging from functional coatings, food science, cosmetology, medical diagnostics and forensics to geophysics and art. This EPJ E Colloquium discusses a wide variety of problems related to the drying of colloidal systems, from the stabilization of dairy products to cracking phenomena that occur at the surface of planets or on an oil painting. The diversity of these processes lies in the great variability in size and/or time scales and makes it very hard to understand and analyse the mechanisms at play. The results presented in this review attest to the reliability of experimental modelling in the laboratory, a clever way to use the drying of complex fluids to reproduce and study original mechanisms.
- Published on 20 August 2018
Natural switching of DNA and RNA polarisation opens possibilities to develop novel biosensors and high-capacity data storage
DNA and RNA are naturally polarised molecules containing electric dipole moments due to the presence of a significant number of charged atoms at neutral pH. Scientists believe that these molecules have an in-built polarity that can be reoriented or reversed fully or in part under an electric field—a property referred to as bioferroelectricity. However, the mechanism of these properties remains unclear. In a new study published in EPJ E, See-Chuan Yam from the University of Malaya, Kuala Lumpur, Malaysia, and colleagues show that all the DNA and RNA building blocks, or nucleobases, exhibit a non-zero polarisation in the presence of polar atoms or molecules such as amidogen and carbonyl. They have two stable states, indicating that DNA and RNA basically have memory properties, just like a ferroelectric or ferromagnetic material. This is relevant for finding better ways of storing data in DNA and RNA because they have a high capacity for storage and offer a stable storage medium. Such physical properties may play an important role in biological processes and functions. Specifically, these properties could also be extremely useful for possible applications as a biosensor to detect DNA damage and mutation.
- Published on 26 June 2018
New study of how positive and negative electrical charge disorder at the ends of polymers acts like a green or red light for proteins to pass through biological membranes
Nature’s way of allowing proteins across its gates, through porous biological membranes, depends, among others, on their electrical charge. For a protein to cross this type of membrane, it needs to be stimulated by an electrical field. A new study focuses on a particular kind of proteins that have multiple functions - dubbed Intrinsically Disordered Proteins - because the electric charge disorder on their surface makes it possible for them to take multiple shapes. In the work, recently published in EPJ E, Albert Johner from the Charles Sadron Institute (part of the CNRS) in Strasbourg, France and Jean-Francois Joanny from Paris reveal how the mixed electrical charge at the ends of the proteins influences biological membrane crossing. This has potential implications for our understanding of how proteins travel across the body, and of disease mechanisms.
- Published on 30 May 2018
Patchy particles is the name given to a large class of systems of mesoscopic particles characterized by a repulsive core and a discrete number of short-range and highly directional interaction sites. Numerical simulations have contributed significantly to our understanding of the behaviour of patchy particles, but, although simple in principle, advanced simulation techniques are often required to sample the low temperatures and long time-scales associated with their self-assembly behaviour.
In this EPJ E colloquium paper, Rovigatti et al. review the most popular simulation techniques that have been used to study patchy particles, with a special focus on Monte Carlo methods.
- Published on 23 May 2018
A new study shows how to couple highly accurate and simplified models of the same system to extract thermodynamics information using simulations
Computer simulations are used to understand the properties of soft matter - such as liquids, polymers and biomolecules like DNA - which are too complicated to be described by equations. They are often too expensive to simulate in full, given the intensive computational power required. Instead, a helpful strategy is to couple an accurate model - applied in the areas of the system that require greater attention - with a simpler, idealised model. In a recent paper published in EPJ E, Maziar Heidari, from the Max Planck Institute for Polymer Research, Mainz, Germany and colleagues make the accurate model in high-resolution coincide seamlessly with an exactly solvable representation at lower resolution.