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Biomedical devices

Biomedical devices

Light-triggered implantable device provides programmable drug delivery

06 Apr 2023 Isabelle Dumé
Light-triggered implantable technology
Drug delivery device: the self-powered implant releases medication when triggered by external pulses of light. (Courtesy: Y Zhang)

A new self-powered drug delivery device has been developed by researchers at Northwestern University in the US. The device can be implanted in the body and triggered to release the medication it is carrying using externally applied light pulses of different wavelengths. The technology, which is the first of its kind, is also absorbable by the body, thus avoiding the need for surgical removal when no longer required.

Implantable drug delivery systems, made from polymer matrices and porous scaffolds, are used to treat conditions ranging from chronic pain to cancer and diabetes, and work by slowly releasing drugs. The amount of drug released cannot, however, be controlled by the patient or doctor, nor can these devices be switched off remotely. Devices that can be controlled for programmable drug release do exist, but they require power supplies and electronics, and surgical extraction after a period of use.

The new device, developed by a team led by John Rogers, Yamin Zhang and Colin Franz, contains three separate drug reservoirs, each controlled by a phototransistor and an optical filter. Three light-emitting diodes (LEDs) of different wavelengths are placed on the skin near to where the device is implanted. These allow the user to trigger a short circuit in an electrochemical cell structure that includes a metal gate valve as its anode. This short circuit induces electrochemical corrosion, which eliminates the gate and opens up the underlying reservoir to release a dose of drug from any one or combination of the reservoirs into surrounding tissue.

Noticeable pain relief

To test their system, Zhang, Franz and colleagues filled the drug reservoirs with lidocaine, a common nerve-pain-blocking medication. They then implanted the device into the right sciatic nerve of rats and placed the LEDs on the skin. Not only did they observe noticeable pain relief in the rodents when drug release was triggered, they were also able to tune the device to provide different degrees of pain relief depending on the LED colour-light sequencing.

According to the researchers, the technology represents a breakthrough that addresses the shortfalls of current drug delivery systems and could provide an effective and safe alternative to systemically delivered pain medications. And while this proof-of-concept test only used three LEDS, this number could potentially be increased to up to 30 different LED wavelengths, offering many more programmes for pain relief, they say.

“We have demonstrated this platform as a system for programmed release of pain-relieving drugs on an as-needed basis,” Rogers tells Physics World. “The same technology could also be used for precise hormone and cancer treatments.”

The Northwestern team is now busy reviewing various additional aspects of biocompatibility and safety prior to seeking US Food and Drug Administration (FDA) clearance for human clinical trials.

The study is detailed in the Proceedings of the National Academy of Sciences.

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