Heat-controlled implant delivers insulin on demand

The field of drug delivery is literally heating up with the development of a new polymer implant that releases insulin in response to changes in temperature. L. Andrew Lyon and his colleagues at the Georgia Institute of Technology in Atlanta designed the new material out of microscopic, water-saturated spheres that are heat sensitive. The researchers loaded these hydrogel particles with insulin and assembled them into a multilayered film.

Dunked into a 40°C bath, the film collapsed and the particles inside contracted and expelled part of their insulin cargo. When the researchers placed the shriveled film in a cooler bath, at 25°C, the particles swelled back up and stopped releasing insulin. Described in the September Biomacromolecules, the material was stable enough to survive repeated cycling through hot and cold phases every day for a month.

The researchers are also working on tuning the hydrogel particles to release insulin at a temperature slightly above body temperature, which is 37°C. Such films might someday be placed on a chip with microscopic heating elements and implanted in patients with diabetes, Lyon says. A timer embedded in the chip could then turn on the heaters and release insulin at specific times of the day, or patients could use a remote control device to control the chip on their own.