A swarm of tiny machines, speeding in concert through the bloodstream to repair an organ or deliver a drug to its target area, microrobots working together to construct a nanotechnological component—although it sounds like science fiction, it is a thoroughly realistic future scenario.
Amazing progress has already been made in the production of autonomous nano- and micromotors, but the little machines have continued to lack in team spirit. To complete challenging tasks, the individual machines must communicate and cooperate with each other.
Researchers led by Ayusman Sen at Pennsylvania State University (USA) have now introduced silver chloride microparticles that can “swarm” together, almost like living single-celled organisms. As reported in the journal Angewandte Chemie, irradiation with UV light causes the particles to give off “signal substances” that “attract” other particles.
Living cells and organisms are able to exchange information with each other to accomplish tasks as a team. Single-celled slime molds, for example, living in unfavorable conditions thus release a special substance. Neighboring slime molds follow the gradient of this signal substance and aggregate in the form of a multi-celled fruiting body. The silver chloride particles used by Sen’s team, which are about 1µm in size, behave in a similar fashion when irradiated with UV light. Silver chloride decomposes under UV light, releasing ions that act as both a propulsion mechanism and signal substance.
This phenomenon is based on diffusiophoresis, the movement of particles along an electrolyte gradient. The silver chloride particles “swim” toward a higher ion concentration. Because of irregularities in the surfaces of the particles and non-uniform irradiation, the degradation of the particles is asymmetric. Different quantities of ions are released in different places on the surface, which results in a local ion gradient around the particles. The particle thus produces its own ion gradient, which propels it at speeds up to 100 µm/s (self-diffusiophoresis). Neighboring sliver chloride particles follow the ion gradient of the solution and “swim” to regions of higher particle density. After several minutes, this results in small, stable “swarms” of particles. Photochemically inactive silicon dioxide particles also react to the ion signal, aggregating around the silver chloride particles.
This system can be used as a nonbiological model for communication between cells. Most importantly though, it represents a new design principle for “intelligent” synthetic nano- or micromachines that can work together as a team.
Author: Ayusman Sen, The Pennsylvania State University, University Park (USA), http://research.chem.psu.edu/axsgroup/dr_sen.html
Title: Schooling Behavior of Light-Powered Autonomous Micromotors in Water
Angewandte Chemie International Edition 2009, 48, No. 18, 3308–3312, doi: 10.1002/anie.200804704
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy