Good news! Amazing stuff!
"Using these particles, which resemble tiny coffee cups sealed with a lid, researchers could design vaccines that would need to be given just once, and would then “self-boost” at a specified point in the future. The particles can remain under the skin until the vaccine is released and then break down, just like resorbable sutures. ...
This approach could also be used to deliver a range of other therapeutics, including cancer drugs, hormone therapy, and biologic drugs, the researchers say. ...
This approach could also be used to deliver a range of other therapeutics, including cancer drugs, hormone therapy, and biologic drugs, the researchers say. ...
The researchers first described their new microfabrication technique for making these hollow microparticles in a 2017 Science paper. The particles are made from PLGA, a biocompatible polymer ...
To create cup-shaped particles, the researchers create arrays of silicon molds that are used to shape the PLGA cups and lids. Once the array of polymer cups has been formed, the researchers employed a custom-built, automated dispensing system to fill each cup with a drug or vaccine. After the cups are filled, the lids are aligned and lowered onto each cup, and the system is heated slightly until the cup and lid fuse together, sealing the drug inside.
This technique, called SEAL (StampEd Assembly of polymer Layers) ...
Their studies of the release mechanism revealed that the PLGA polymers that make up the particles are gradually cleaved by water, and when enough of these polymers have broken down, the lid becomes very porous. Very soon after these pores appear, the lid breaks apart, spilling out the contents. ...
To their surprise, the researchers found that particle size and shape had little effect on drug release kinetics. ... Instead, the PLGA particles release their payload at different times based on differences in the composition of the polymer and the chemical groups attached the ends of the polymers.
“If you want the particle to release after six months for a certain application, we use the corresponding polymer, or if we want it to release after two days, we use another polymer,” ..."
From the abstract:
"Next-generation therapeutics require advanced drug delivery platforms with precise control over morphology and release kinetics. A recently developed microfabrication technique enables fabrication of a new class of injectable microparticles with a hollow core-shell structure that displays pulsatile release kinetics, providing such capabilities. Here, we study this technology and the resulting core-shell microstructures. We demonstrated that pulsatile release is governed by a sudden increase in porosity of the polymeric matrix, leading to the formation of a porous path connecting the core to the environment. Moreover, the release kinetics within the range studied remained primarily independent of the particle geometry but highly dependent on its composition. A qualitative technique was developed to study the pattern of pH evolution in the particles. A computational model successfully modeled deformations, indicating sudden expansion of the particle before onset of release. Results of this study contribute to the understanding and design of advanced drug delivery systems."
Experimental and computational understanding of pulsatile release mechanism from biodegradable core-shell microparticles (open access)
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