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NEWS
Nanoscale “Glass” Bottles Devised For Targeted Drug Delivery
August 29, 2019

Tiny silica bottles filled with medicine and a special temperature-sensitive material could be used for drug delivery to kill malignant cells only in certain parts of the body, according to a study published recently by researchers at the Georgia Institute of Technology.


This scanning electron microscopy image shows the nanocapsules once formed after the removal of the gold nanoparticles and polystyrene beads, leaving behind an opening that can be used to fill the capsules with a payload. Credit: Jichuan Qiu

According to information, the research team devised a way to create silica-based hollow spheres around 200 nanometers in size, each with one small hole in the surface that could enable the spheres to encapsulate a wide range of payloads to be released later at certain temperatures only.

In the study, “Encapsulation of a Phase-Change Material in Nanocapsules with a Well-Defined Hole in the Wall for the Controlled Release of Drugs,” which was published in the journal Angewandte Chemie International Edition, the researchers describe packing the spheres with a mixture of fatty acids, a near-infrared dye, and an anticancer drug. The fatty acids remain solid at human body temperature but melt a few degrees above. When an infrared laser is absorbed by the dye, the fatty acids will be quickly melted to release the therapeutic drug.

“This new method could allow infusion therapies to target specific parts of the body and potentially negating certain side effects because the medicine is released only where there’s an elevated temperature,” said Younan Xia, professor and Brock Family Chair in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “The rest of the drug remains encapsulated by the solid fatty acids inside the bottles, which are biocompatible and biodegradable.”

The researchers also showed that the size of the hole could be changed, enabling nanocapsules that release their payloads at different rates.

To make the silica-based bottles, the research team started by fabricating spheres out of polystyrene with a small gold nanoparticle embedded in its surface. The spheres are then coated with a silica-based material everywhere except where the gold nanoparticle is embedded. Once the gold and polystyrene are removed, only a hollow silica sphere with a small opening remains. To adjust the size of the opening, the researchers simply changed the size of the gold nanoparticle.

The process to load the bottles with their payload involves soaking the spheres in a solution containing the mixture, removing the trapped air, then washing away the excess material and payload with water. The resulting nanocapsules contain an even mixture of the temperature-sensitive material, the therapeutic drug, and the dye.

This research was grant supported by the National Science Foundation through the National Nanotechnology Coordinated Infrastructure. The work was also supported by the China Scholarship Council through a graduate student fellowship.


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