Researchers from several U.S. universities this week announced a new diabetes treatment method that uses a "smart sponge" as a drug delivery device. The injectable sponge-like material surrounds an insulin core, expanding and contracting in response to blood sugar levels to regulate the amount of insulin released. The researchers also believe the technique could be used as a targeted cancer cell drug delivery device. A study of the device and how it works has been published in the journal ACS Nano.
"We wanted to mimic the function of healthy beta-cells, which produce insulin and control its release in a healthy body," said Zhen Gu, lead author of the research and an assistant professor at North Carolina State University. "But what we've found also holds promise for smart drug delivery targeting cancer or other diseases."
The tiny (250 micrometer) sponges are made out of a substance found in shrimp and crab shells called chitosan. Using the material, researchers created a spherical matrix containing small segments of glucose oxidase or catalase enzymes. As blood sugar rises, glucose causes a chemical reaction that positively charges the sponge, causing the strands of the chitosan matrix to spread apart and allow more of the insulin core to flow into the bloodstream. As glucose levels in the bloodstream begin to drop, the matrix begins to lose its positive charge and shrinks, trapping the insulin inside.
The system was effective for regulating blood sugar in mice for up to two days. A more recent version, however, regulated blood sugar for up 10 days.
"We can also adjust the size of the overall 'sponge' matrix as needed, as small as 100 nanometers," said Gu. "And the chitosan itself can be absorbed by the body, so there are no long term health effects."
(Image courtesy Zhen Gu)