A team of researchers from Waseda University (Tokyo, Japan), the National Defense Medical College (Tokorozawa, Japan), and the Japan Science and Technology Agency (Saitama, Japan) has developed a bioadhesive, wirelessly powered light-emitting device that could better treat cancer in delicate organs.
Conventional photodynamic therapy (PDT) induces cancer cell death by using photosensitizing agents, which localize in tumors and activate with exposure to a specific wavelength of light. In recent years, a low-dose and long-term PDT method known as metronomic photodynamic therapy (mPDT) has shown promise in treating cancer in internal organs. With mPDT, however, the light intensity is extremely low (1/1000 of the conventional method) so that the antitumor effect cannot be obtained if the light source shifts even slightly away from the tumor, making the illumination insufficient.
"To address this issue, we have developed a wirelessly powered optoelectronic device that stably fixes itself onto the inner surface of an animal tissue like a sticker with bioadhesive and elastic nanosheets, enabling a continuous, local light delivery to the tumor," says Toshinori Fujie, associate professor of biomedical engineering at Waseda University. The nanosheets are modified with protein-inspired polymer polydopamine, which can stabilize the device onto a wet animal tissue for more than two weeks without surgical suturing or medical glue. The light-emitting diode (LED) chips in the device are wirelessly powered by near-field-communication technology.
A schematic of the newly developed bioadhesive, wirelessly powered implant is shown. (Image courtesy of Dr. Toshinori Fujie, Waseda University)
To test its effectiveness, tumor-bearing mice implanted with the device were injected with a photosensitizing agent (photofrin) and exposed to red and green light, approximately 1000-fold intensity lower than conventional PDT approaches, for 10 consecutive days. The experiment showed that the tumor growth was significantly reduced overall. Especially under green light, the tumor in some mice was completely eradicated.
"This device may facilitate treatment for hard-to-detect microtumors and deeply located lesions that are hard to reach with standard phototherapy, without having to worry about the risk of damaging healthy tissues by overheating," Fujie explains. "Furthermore, because the device does not require surgical suturing, it is suitable for treating cancer near major nerves and blood vessels, as well as for organs that are fragile, that change their shape, or that actively move, such as the brain, liver, and pancreas."
If clinically applied, the device could be beneficial for cancer patients who seek minimally invasive treatment, helping them live longer and improve their quality of life.
Full details of the work appear in the journal Nature Biomedical Engineering.