#microparticles

Researchers use low-cost 3D printer to develop new method for creating microspheres

Researchers use powerful microchannel droplet generation equipment to create uniform polymer microsphere materials, which have high economic values. These microspheres are spherical microparticles that can be used in many applications including medical devices, biotechnology, the construction industry, veterinary science, and environmental studies.

A team of researchers has developed a novel method for building high throughput microchannel droplet generation equipment, which greatly reduces the numbers of integrating droplet generators inside, and can be easily realized via commercial low-cost 3D-print fabrication.

Their findings are published in the journal Particuology on October 22.

The team built a prototype device with only four parallel droplet generators using a low-cost 3D print method. The prototype device worked with the same capacity as a conventional microchannel device containing hundreds of parallel droplet generators. In addition to developing the advanced microchannel droplet generation equipment, the team also developed a two-step emulsion template polymerization procedure that turns the droplets into solid particles.

Achilles Heal

Perhaps if this research had come just a few millennia earlier, Achilles’ heel wouldn’t have been such a vulnerability. Researchers working to improve recovery for people with tendon and ligament injuries are increasingly interested in synthetic hydrogels – injectable material that can encourage regrowth. There have also been recent strides in techniques that use microparticles to deliver dissolvable factors to the right spot. Now a study has combined these approaches to create a hydrogel system with fibres (pink) and microgels (green) carrying dissolvable factors. Starter cells for regrowth (blue/yellow) were recruited along the fibres, their development helped by both the physical landscape and the delivery of soluble cues in a lab model (pictured) and in ruptured mouse Achilles tendons. If the injection of a hydrogel including fibres and microparticles can boost the body’s ability to repair, recovery time after all too common tendon and ligament injuries could be greatly reduced.

Written by Anthony Lewis

Image from work by Robert N. Kent III and colleagues

Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA

Image originally published with a Creative Commons Attribution – NonCommercial – NoDerivs (CC BY-NC-ND 4.0)

Published in Advanced Functional Materials, September 2022

Microparticles show ability to turn in reverse, paving the way for microfluidic devices

Like middle school students, microparticles are not the world's most graceful dancers. For many of them, it's one step forward, one step back.

In a new study from the U.S. Department of Energy's (DOE) Argonne National Laboratory, researchers have identified how a self-organized vortex of rotating microparticles in a fluid will reverse direction when an electric stimulus is interrupted and then reapplied with the same orientation, providing fundamental insights into mechanisms behind the sudden switch in rotation. The research offers potential inspiration for pumps in microsized channels, called microfluidic pumps, that allow the controlled flow of liquids. Such pumps allow precise fluid delivery for biomedical, chemical and electronics applications.

These vortices of microparticles, which are engineered particles less than a millimeter in diameter, show evidence of what scientists call "emergent behavior"—a kind of self-organization and collective motion. In their native state, the particles are distributed randomly, but when scientists apply an electric field, they begin to synchronize their motion and rotate together either clockwise or counterclockwise.

'Harvesting' microparticles from a liquid jet

Microspheres, microlenses and microfibers can now be produced by irradiating a fluid jet with ultraviolet light. The result is that locally, a polymer of a desired shape is formed. This process, called in-air photopolymerization, enables manufacturing of a wide range of bio-inspired microparticles. The technique is faster than existing techniques and delivers particles of very constant quality. Researchers at the University of Twente present their work in Advanced Materials of 4 December.

Bio-inspired materials are in high demand, including microparticles that stimulate blood circulation or improve vaccine delivery, patches with microneedles that painlessly inject microfibers attaching themselves to your body, and microlenses mimicking insect eyes. These require well-defined building blocks that can be assembled in vast quantities. Still, existing manufacturing processes are labor intensive, too slow, difficult to tailor or result in excess size deviation. Creating the particles can be done using lab-on-a-chip technology, which is accurate but slow, or using chemical etching techniques requiring several processing steps. In their study, the researchers show that it is possible to produce the desired particles from an ongoing liquid stream at up to 4000 particles per second.

Synthetic Microswimmers: Inanimate Microparticles Display Complex Behavior

TU Dresden Freigeist fellow Dr Juliane Simmchen is investigating with her multidisciplinary junior research group the motion of synthetic microswimmers in liquids. Her goal is to enable these inanimate microparticles to move in a certain direction of their own accord and thus, in future, to be used in sensor technology or biological cleaning. “Actually, it’s a bit like playing computer games in the laboratory,” the chemist describes her extraordinary research work in an interview with the Volkswagen Foundation.

The Simmchen group is working with the so-called “Janus particles.” These consist of a body of titanium dioxide with two differently coated sides: one side with a catalytically active layer of nickel and gold, the other side remains untreated. Titanium dioxide is used as a whitening agent, for example in wall paint, but it also reacts with light. As a result, Janus particles are photocatalytic, which means that as soon as light hits them, chemical reactions occur that set off a movement.

New Study Finds Even More Microplastics in Your Body

The more experts learn about microplastics and their impact on human bodies, the worse it seems to get. Just this week researchers at the Medical University of Vienna published a new study in the journal Exposure and Health that summarizes all the current knowledge about micro- and nanoplastic particles (MNPs), and how they end up in our gut. Spoiler alert — it’s almost 100,000 particles per year…