Wireless PDT Implantable Device for Targeted Cancer Therapy

A wireless technique to deliver light into the deep regions of the body has been developed by a research group at the National University of Singapore. This wireless delivery of light is to activate light-sensitive drugs for photo dynamic therapy (PDT) which is a targeted cancer treatment.

While PDT is an effective light-induced cancer treatment, it is often limited to surface cancers because of the low penetration of light through biological tissue. This wireless approach of light delivery enables PDT to be used on the wider range of the body with fine control.

This technology could potentially enable PDT to be used to treat a brain cancer and liver cancer.

Wireless PDT Implantable Device for Targeted Cancer Therapy

“This wireless approach of light delivery for treating cancers with PDT will give significant advantages. Powered wirelessly, the tiny implantable device to shine new light over long time scales in a programmable and repeatable way. This could potentially enable the treatments to be tailored by the clinician over the course of treatment”, Asst Prof Ho stated.

Understanding photodynamic therapy:

PDT is a treatment method that uses a light-sensitive drug called a photosensitizer that is activated by a specific wavelength of light, to produce a form of oxygen that kills nearby cells. This gives a precision approach to cancer therapy that overcomes many of the whole-body side effects of classical drugs such as chemotherapy.

Notwithstanding directly killing cancer cells, PDT shrinks or destroys tumors by damaging blood vessels in the tumor, preventing the cancer cells from receiving necessary nutrients. PDT may also trigger the immune system to attack the tumor cells.

Notwithstanding, PDT has so far been limited to the treatment of surface cancers. Traditional light sources such as light-emitting diodes (LEDs) or lasers might be used, but the low penetration of light through tissue limits the depth to less than a centimeter.

For the inner lining of some organs, such as the esophagus, an endoscope a thin, lighted tube used to look at tissues inside the body can be used to insert a fiber optic cable, but other regions can’t be accessed by this way easily. PDT can be used for organs such as the brain or liver, the organ must be exposed by surgery before.

Wireless light switch:

The research group’s novel approach of enabling PDT to be used for the inner organs of the body is achieved by inserting a tiny wireless device at the objective site, extending the spatial and temporal precision of PDT deep within the body.

The miniaturized device, which weighs 30 mg and is 15 mm3 in size, can be easily implanted and uses a wireless powering system for light delivery. Once the device has been implanted at the objective site, a specialized radio-frequency system wirelessly powers the device and monitors the light-dosing rate.

The group demonstrated the therapeutic efficacy of this approach by activating photosensitizers through thick tissues more than three centimeters inaccessible by direct illumination and by delivering multiple controlled doses of light to suppress tumor growth.

Prof Zhang said, “This novel approach enables ongoing treatment to prevent re-occurrence of cancer, without additional surgery. The application of the technology can also be extended to many other other light-based treatments such as photothermal therapy, that face the common problem of limited penetration depth. We hope to bring these capabilities from bench to beside to give new opportunities to shine a light on human diseases”.

The group is presently working on developing nano systems for targeted delivery of photosensitizers. They are also coming up with minimally invasive techniques for implanting the wireless devices at the objective site and looking into integrating sensors to the device to monitor the treatment response in real-time.

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