Developing better fabrication techniques for pH-responsive microcapsules

June 09, 2020

Researchers have developed a new method to create microcapsules, which are tiny droplets surrounded by a solid shell. The technique can be used to make microcapsules that respond to changes in pH, which are useful for applications such as anti-corrosion coatings.

The study "Fabrication of pH-responsive monodisperse microcapsules using interfacial tension of immiscible phases" was published in the journal Soft Matter.

"There are a number of ways that have been used to make microcapsules," said Nancy Sottos, a Maybelle Leland Swanlund Chair and head of the Department of Materials Science and Engineering at the University of Illinois at Urbana-Champaign. "However, those methods are tedious, slow, and they clog the devices. Additionally, the capsules are not the same size."

The new technique, developed by members of the Autonomous Materials Systems Group at the Beckman Institute for Advanced Science and Technology, involves using emulsion templates to make the microcapsules. "It's like making a salad dressing. You slowly mix in the oil to the water. The faster you mix, the smaller the droplets. Then you form a shell wall around the emulsion droplets." said Sottos, who is the AMS Group leader.

The researchers used a needle that contains capillary tubes inside it. The liquid core of the microcapsule enters through a central tube and the shell material comes through an outer tube. The needle vibrates uniformly across the surface of water. When the needle crosses the surface, the droplets are detached from the capillary tubes, forming uniformly sized emulsion droplets for microcapsules.

"This technique gives you control over the shell thickness, the core volume, and the overall size of the capsule," said Dhawal Thakare, a graduate student in the AMS Group. "Our technique is simple and can be assembled very easily in a lab environment."

Using this technique, the researchers have made pH-responsive capsules that can break open when there is a pH change in the environment. "Drug delivery often uses pH changes to release the capsule contents. We were interested in using them to encapsulate anti-corrosive agents," Sottos said. "When the pH changes, the microcapsules open up and release the anti-corrosive agents."

"Although the technique gives you precise control over the microcapsules, it is hard to make capsules that are very small. Another disadvantage is that you are introducing fluids through capillaries. As the viscosity of the fluid increases, the pressure increases, and there are higher chances of not attaining an unobstructed flow," Thakare said.

The researchers are interested in expanding the range of materials that they can encapsulate and improve the technique so that they can make smaller microcapsules.
The study was funded by the BP International Centre for Advanced Materials.

The researchers on the paper also include Grayson Schaer, an undergraduate researcher in the AMS Group, and Mostafa Yourdkhani, a former postdoctoral researcher in the AMS Group.

Editor's Note: The study "Fabrication of pH-responsive monodisperse microcapsules using interfacial tension of immiscible phases" can be found at 10.1039/D0SM00301H.

Beckman Institute for Advanced Science and Technology

Related Engineering Articles from Brightsurf:

Re-engineering antibodies for COVID-19
Catholic University of America researcher uses 'in silico' analysis to fast-track passive immunity

Next frontier in bacterial engineering
A new technique overcomes a serious hurdle in the field of bacterial design and engineering.

COVID-19 and the role of tissue engineering
Tissue engineering has a unique set of tools and technologies for developing preventive strategies, diagnostics, and treatments that can play an important role during the ongoing COVID-19 pandemic.

Engineering the meniscus
Damage to the meniscus is common, but there remains an unmet need for improved restorative therapies that can overcome poor healing in the avascular regions.

Artificially engineering the intestine
Short bowel syndrome is a debilitating condition with few treatment options, and these treatments have limited efficacy.

Reverse engineering the fireworks of life
An interdisciplinary team of Princeton researchers has successfully reverse engineered the components and sequence of events that lead to microtubule branching.

New method for engineering metabolic pathways
Two approaches provide a faster way to create enzymes and analyze their reactions, leading to the design of more complex molecules.

Engineering for high-speed devices
A research team from the University of Delaware has developed cutting-edge technology for photonics devices that could enable faster communications between phones and computers.

Breakthrough in blood vessel engineering
Growing functional blood vessel networks is no easy task. Previously, other groups have made networks that span millimeters in size.

Next-gen batteries possible with new engineering approach
Dramatically longer-lasting, faster-charging and safer lithium metal batteries may be possible, according to Penn State research, recently published in Nature Energy.

Read More: Engineering News and Engineering Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to