The new synthesis method gives researchers an extraordinary degree of control over the shape and chemical properties of the microparticles, which range in size from about 1 millionth of a meter to a millimeter.
"We have precise control over shape and an ability to create patterned chemical regions, that is rather unprecedented," said Assistant Professor Patrick Doyle of chemical engineering, one of the authors of a report appearing in the online edition of Nature Materials on April 9.
Doyle says he hopes other researchers will adopt his team’s new technique of continuous flow lithography (CFL), which allows for faster, easier production of microparticles of diverse shape, size and chemical composition.
CFL builds on the well-known technique of photolithography but its novelty lies in the fact that it is performed in a laminar (not turbulent) flowing stream as opposed to the traditionally used stationary film. Wherever pulses of ultraviolet light strike the flowing stream of small building blocks, or oligomers, a reaction is set off that forms a solid polymeric particle in a process known as photopolymerization.
The method makes use of microfluidics - tiny fluid-filled channels with cross-sections typically smaller than a strand of hair. Until now, microfluidic methods have been limited to producing spheres, discs or cylinders. However, with CFL, the particles can be configured into just about any projected 2D shape the researchers want by using a transparency mask to define the shape of a beam of ultraviolet light and focusing it with a microscope. As liquid flows through a microfluidic device, where the synthesis occurs, the shape is repeatedly imprinted onto the oligomer stream, at a rate of about 100,000 particles per hour with the current simple design.
"From an engineering point of view, converting a batch process (photolithography) to a continuous process may have significant advantage when we consider scaling up the technique," said graduate student Dhananjay Dendukuri, lead author on the paper.
The researchers can also create particles with different chemical properties in different locations - for example, a rod that is hydrophilic (water-loving) at one end and hydrophobic (water-fearing) at the other. Such particles are examples of so-called Janus particles, after the Roman god with a double-faced head, and may find use in e-paper technologies or as new building blocks for self-assembled structures.
The new method also makes it easier to create "barcoded" particles, which have an array of chemical properties in different locations. Instead of adding "stripes," or chemical properties, one at a time, the new technique allows them all to be added at once, said Doyle.
Potential medical applications for such particles include drug delivery and performing diagnostic tests, such as testing blood for the presence of certain antibodies or other proteins. Graduate student Daniel Pregibon, one of the authors, said he is interested in creating ring-shaped particles, or "cell cages," that would trap cells for high throughput single cell studies.
Other authors on the paper are Alan Hatton, Ralph Landau Professor of Chemical Engineering Practice, and senior physics major Jesse Collins.
The research was supported by a National Science Foundation grant.
Elizabeth A. Thomson | MIT News Office
Making fuel out of thick air
08.12.2017 | DOE/Argonne National Laboratory
‘Spying’ on the hidden geometry of complex networks through machine intelligence
08.12.2017 | Technische Universität Dresden
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."
Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...
08.12.2017 | Event News
07.12.2017 | Event News
05.12.2017 | Event News
08.12.2017 | Life Sciences
08.12.2017 | Information Technology
08.12.2017 | Information Technology