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A New Approach to Injectable Microgels for Controlled Drug Release
Recent research from the University of Michigan unveils a novel and simplified method for creating injectable microgels that permit the controlled release of various medications. This advancement helps enhance the scalability and accessibility of microgel production.
Microgels are small hydrogel particles, ranging in size from 1 to 100 micrometers, composed of natural or synthetic polymers with high water content. These microgels can encapsulate smaller drug particles, facilitating precisely controlled release rates, a process known as programmable delivery. By adjusting properties such as particle size, swelling characteristics, and molecular cross-linking, scientists can tailor the release profile of the drugs embedded within these gels.
“Microgel suspensions combine the solidity necessary for targeted drug delivery with the fluidity associated with liquids, making them exceptionally suited for injection,” explained Albert Liu, an assistant professor in chemical engineering at U-M and the study’s corresponding author, which is available in Chem & Bio Engineering.
Using a single injection that releases multiple drugs at different intervals can significantly reduce the invasiveness of medical procedures. For example, in specific cancer treatments, one microgel injection could deliver immediate medication to target tumor cells, a longer-lasting drug to hinder blood vessel growth, and a delayed-action drug to manage side effects or tumor responses.
Historically, microgel production relied on the intricate formation of covalent bonds, which provided precise timing for drug release but necessitated specialized equipment and chemicals, limiting accessibility for many research laboratories and industries.
The research team developed a more straightforward method of fabricating injectable microgels by utilizing ionic bonds, which are less stable than covalent bonds but easier to manipulate. “We are confident that this represents one of the simplest synthesis methods for microgels, offering excellent reproducibility,” stated Sungwan Park, a doctoral student in chemical engineering at U-M and co-author of the study.
The innovative process begins by combining alginate, a carbohydrate derived from brown algae, with calcium to form the microgel. Subsequent treatment in ionic baths involving substitutes like magnesium or sodium replaces the stronger calcium-alginate bond with one that is easier to break. By fine-tuning parameters such as ion bath duration and concentration, researchers can precisely control the ratios of calcium and magnesium or sodium in the microgels, affecting the overall matrix size and, consequently, the drug release rate. By mixing different ionic-exchanged microgels, various pre-programmed release profiles can be achieved in a single formulation.
Advanced microscopy techniques played a key role in characterizing the physical attributes of microgels that influence drug release, such as surface texture, ion distribution uniformity, and swelling patterns. “The range of variations is vast, and we see potential for further optimization, including testing additional factors like alginate concentration or centrifuge spin speed,” remarked Jihpeng Sun, a doctoral student and co-lead author.
To validate their findings, the researchers encapsulated brightly colored test drugs in the microgels, allowing for easy observation of drug release patterns. The study illustrated how manipulating ion-exchange processes and drug combinations can result in tailored drug release profiles.
“We aim for the simplicity of this method to enable anyone interested in controlled drug delivery to implement this approach, free from the need for costly equipment or extensive troubleshooting,” added Liu.
Additionally, high school student Fiona Nikolla from the Gene L. Klida Academy for International Studies in Sterling Heights, Michigan, contributed to this significant research.
More Information:
Rong Ma et al, Programmable Cargo Release from Jet-Printed Microgel Particles via an In Situ Ionic Exchange Method, Chem & Bio Engineering (2025). DOI: 10.1021/cbe.5c00017
Citation: A simpler way to make microgels for programmable drug release (2025, April 28) retrieved 28 April 2025 from Phys.org
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phys.org