Disappearing Silk-Based Optical Medical Patches

Texas Engineering professor Tiger H. Tao and his team of researchers have developed the first silk-based optical medical devices that serve as antibacterial patches and can be programmed to deliver drugs over time before they disappear into the body. The researchers describe how their biocompatible, biodegradable patches release antibiotics in a paper published on Feb. 13 in Advanced Materials.

While biocompatible drug-delivery devices aren’t new, the team’s device is different because it is made from biodegradable silk that can be placed on top of the skin or inside the body for drug stabilization and drug release while simultaneously providing optical feedback of the drug delivery. There’s a growing demand for these types of implantable devices that stay functional within medically useful time frames but then completely disappear via resorption by the body without the need of a second surgery to remove the devices.

Tao and his team developed a diffractive optical element device, typically made of glass or synthetic polymers, out of silk. To create the patch, they imprinted the silk with a pattern and inserted antibiotics into the silk layers. They then demonstrated in an animal model how water vapor activates the release of the antibiotics and it degrades inside the model. The patch can be programmed to degrade within a few minutes to a few months. Researchers can see the drug release in real time by simply flashing a laser pointer on the patch and seeing the pattern decay.

“The key is in how the biofluid interacts with the material and ‘washes away’ the structure and releases the embedded drug,” Tao said. “We were able to monitor drug release by looking at the deterioration of the optical pattern.”

The University of Texas at Austin researchers proved that optical devices can be used to deliver drugs, conceal data and act as biosensors, measuring hydration level and other physiological responses. This work sheds light on a new class of transient optical devices — with specific functionalities — that can physically degrade in the body or disappear in the environment at prescribed times and controlled rates. The team is continuing to study the medical uses of their silk-based optical devices and have plans to conduct further animal trials.

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