#microgels

Building Back Better

You slip, trip or fall and crack...your bone breaks. The bigger the break, the longer it takes to heal, as bone and blood vessels rebuild. Sometimes a bone graft is needed for complete recovery. However, current engineered bone grafts promote bone formation alone. Researchers now present a scaffold that promotes bone and blood vessel formation – microgels containing proteins that mimic the matrix in which bone cells sit. When human mesenchymal stem cells (MSCs) were added to microgels containing chitosan, gelatin and hydroxyapatite, they attached and matured into bone cells. Next, MSCs were added to microgels containing only gelatin. Fluorescence microscopy revealed MSCs attached (pictured, left), stretched out (right) and matured into networks of endothelial cells, which line blood vessels. Combining the two microgels encouraged and enhanced bone and blood vessel formation. This lays the foundation for creating scaffolds that promote both new bone and blood vessels to heal fractures.

Written by Lux Fatimathas

Image from work by Matthew D. Patrick and Jeremy F. Keys, and colleagues

Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Scientific Reports, September 2022

Uncovering microgel mysteries

Researchers at Shinshu University successfully recorded previously unexplained behavior of hydrogel microspheres (microgels) using a newly customized tool: temperature-controlled high-speed atomic force microscopy (TC HS AFM). This machine, which is the only one in the world, was assembled by Dr. Takayuki Uchihashi of Nagoya University to investigate proteins. It was applied for the first time to the study of microgels by the team at Daisuke Suzuki Laboratory, Graduate School of Textile Science & Technology and RISM (Research Initiative for Supra-Materials) of Shinshu University. The study lead by first year doctoral candidate, Yuichiro Nishizawa, succeeded in observing the structure of the microgels which had been difficult due to limitations of previous equipment.

The structure of microgels has been studied extensively using scattering and imaging techniques including electron microscopy, fluorescence microscopy, atomic force microscopy, and super-resolution microscopy. The thermoresponsive properties of the core-shell structures had been well documented using such techniques. Using TC HS AFM, they were able to observe and record the particles in detail, non-thermoresponsive inhomogeneous decanano-scale spherical domains, which had been hypothesized by Dr. Kenji Urayama of the Kyoto Institute of Technology.

Microgel composite could overcome fibrin blockade to accelerate healing

In regenerative medicine, the ideal repair material would offer properties that seem impossibly contradictory. It must be rigid and robust enough to be manipulated surgically, yet soft and porous enough to allow healing cells to pass through it to launch repair and regeneration processes.

Now, researchers have taken an important step toward creating such a material by combining water-filled particles known as microgels with robust polymer networks made of natural fibrin. In a remarkable dynamic process, the microgels self-assemble into three-dimensional tunnel-like structures that could allow repair cells to migrate through the polymer network to begin the healing process.

The research, resulting from collaboration between biomedical engineers, materials scientists and physicists, could give surgeons a new tool for repairing major injuries and lead to development of a battlefield bandage that soldiers might use to control bleeding – while allowing healing to begin more quickly. Supported by the National Institutes of Health, the Department of Defense and the National Science Foundation, the research was reported January 19 in the journal Proceedings of the National Academy of Sciences.

Droplet-Based Microgels: Attractive Materials for Drug Delivery Systems by Sammer-ul Hassan* in Crimson Publishers: Peer Reviewed Material Science Journals 

Microgels are materials that have the properties to swell and shrink when exposed to external stimuli, i.e. temperature and pH. Therefore, they are instrumental in the field of drug delivery, but their production is complicated. Different strategies have been used to produce microgels from which emulsion polymerization and microfluidic techniques are commonly used. Lab-on-a-chip devices are handy and alternative tools to produce microgels because they provide control on the size, shape and reproducible production of microgels. This review will highlight the ways how to initiate polymerization inside droplets and convert them into microgels using lab-on-a-chip devices.

For more Open access journals in Crimson Publishers please click on below link https://crimsonpublishersresearch.com/

It takes more than peer pressure to make large microgels fit in

When an assembly of microgel particles includes one particle that's significantly larger than the rest, that oversized particle spontaneously shrinks to match the size of its smaller neighbors. This self-healing nature of the system allows the microparticles to form defect-free colloidal crystals, an unusual property not seen in systems made up of "hard" particles.

In 2009, Andrew Lyon, then a professor of chemistry at the Georgia Institute of Technology, observed this dynamic resizing in a microgel system he had created, but the mechanism behind the self-healing process remained uncertain. Now, researchers believe they've finally solved the mystery, and what they've learned could also have implications for biological systems made up of soft organic particles not unlike the polymer microgels.

Using small-angle X-ray and neutron scattering techniques, the researchers carefully studied the structures formed by dense concentrations of the microparticles. They also used tiny piezoelectric pressure transducers to measure osmotic pressure changes in the system. Their conclusion: In dense assemblies of microparticles, counter ions bound to the microgels by electrostatic attraction come to be shared by multiple particles, increasing the osmotic pressure which then works to shrink the oversized particle.