Photoluminescent Nanoparticles Kill Cancer

Researchers discover novel nanoparticle that when triggered by X-rays can treat tumor tissue

2 min read
Photoluminescent Nanoparticles Kill Cancer
This figure from the paper shows the X-ray destruction of human breast cancer cells using Cu-Cy particles. The images show the live cancer cells stained green and the dead cells stained red
Images: University of Texas at Arlington

In a case of serendipity, researchers at the University of Texas at Arlington started out trying to develop new security-related radiation detection and stumbled upon a potential breakthrough in cancer treatment.

In the research, which will be published in the August edition of the Journal of Biomedical Nanotechnology (“A New X-Ray Activated Nanoparticle Photosensitizer for Cancer Treatment”), Wei Chen, professor of physics at the UT Arlington, was exposing copper-cysteamine (Cu-Cy) nanoparticles to X-rays when he noticed an unusual luminescence over a time-lapse exposure. When he investigated the cause of the Cu-Cy nanoparticle luminescence, he realized that the particles were losing energy as they emitted singlet oxygen, a toxic byproduct that also happens to be used to in photodynamic cancer therapy to damage cancer cells.

“This new idea is simpler and better than previous photodynamic therapy methods. You don’t need as many steps. This material alone can do the job,” Chen, who is also leading federally-funded cancer research, said in a press release. “It is the most promising thing we have found in these cancer studies and we’ve been looking at this for a long time.”

Photodynamic therapy (PDT) is a technique in which some photosensitizer is introduced into tumor tissue. When exposed to light, the photosensizer produces singlet oxygen that kills the cancer cells. Two years ago, this blog covered research from Rice University related to a similar PDT technique in which gold nanoparticles were introduced near a tumor and then subjected to light. This light exposure to the cluster of nanoparticles created bubbles that burst, temporarily ripping open small pores in the cell membranes that allow drugs to penetrate. 

The problem with PDT techniques is that the light cannot penetrate very far into human tissue to activate the nanoparticles. Chen and his colleagues have discovered that Cu-Cy the nanoparticle's sensitivity to X-rays and the ability of X-rays to penetrate deeply into tissue means that the tumor can be deep inside tissue and still be effective. Another advantage of the Cu-Cy nanoparticle in combination with the X-rays is that no other photosensitizer needs to be used, making it convenient, efficient and cost-effective, according to the researchers.

Like some of the “theranostic” nanoparticles that are being developed, in which both therapeutic and diagnostic functions are combined into one nanoparticle, the Cu-Cy nanoparticle can serve both as treatment for cancer as well as for cell imaging.

In experiments carried out thus far, Chen and his team have used the Cu-Cy nanoparticle and X-ray combination to treat a tumor. The results over a 13-day period showed that the tumor had not grown at all with the treatment while a tumor that had not been treated grew three times in size.

The UT Arlington has applied for a patent on the technology. Meanwhile Chen and his team are working on ways to shrink the size of the Cu-Cy nanoparticles, which currently are around 250 nanometers, so that the tumor tissue can more easily absorb them. If they can reduce the nanoparticles down to dimensions below 200nm, this should improve cell uptake. Ideally, they would like to bring those dimensions down to around 50 to 100nm.

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Restoring Hearing With Beams of Light

Gene therapy and optoelectronics could radically upgrade hearing for millions of people

13 min read
A computer graphic shows a gray structure that’s curled like a snail’s shell. A big purple line runs through it. Many clusters of smaller red lines are scattered throughout the curled structure.

Human hearing depends on the cochlea, a snail-shaped structure in the inner ear. A new kind of cochlear implant for people with disabling hearing loss would use beams of light to stimulate the cochlear nerve.

Lakshay Khurana and Daniel Keppeler

There’s a popular misconception that cochlear implants restore natural hearing. In fact, these marvels of engineering give people a new kind of “electric hearing” that they must learn how to use.

Natural hearing results from vibrations hitting tiny structures called hair cells within the cochlea in the inner ear. A cochlear implant bypasses the damaged or dysfunctional parts of the ear and uses electrodes to directly stimulate the cochlear nerve, which sends signals to the brain. When my hearing-impaired patients have their cochlear implants turned on for the first time, they often report that voices sound flat and robotic and that background noises blur together and drown out voices. Although users can have many sessions with technicians to “tune” and adjust their implants’ settings to make sounds more pleasant and helpful, there’s a limit to what can be achieved with today’s technology.

8 channels

64 channels

Since optogenetic therapies are just beginning to be tested in clinical trials, there’s still some uncertainty about how best to make the technique work in humans. We’re still thinking about how to get the viral vector to deliver the necessary genes to the correct neurons in the cochlea. The viral vector we’ve used in experiments thus far, an adeno-associated virus, is a harmless virus that has already been approved for use in several gene therapies, and we’re using some genetic tricks and local administration to target cochlear neurons specifically. We’ve already begun gathering data about the stability of the optogenetically altered cells and whether they’ll need repeated injections of the channelrhodopsin genes to stay responsive to light.

Our roadmap to clinical trials is very ambitious. We’re working now to finalize and freeze the design of the device, and we have ongoing preclinical studies in animals to check for phototoxicity and prove the efficacy of the basic idea. We aim to begin our first-in-human study in 2026, in which we’ll find the safest dose for the gene therapy. We hope to launch a large phase 3 clinical trial in 2028 to collect data that we’ll use in submitting the device for regulatory approval, which we could win in the early 2030s.

We foresee a future in which beams of light can bring rich soundscapes to people with profound hearing loss or deafness. We hope that the optical cochlear implant will enable them to pick out voices in a busy meeting, appreciate the subtleties of their favorite songs, and take in the full spectrum of sound—from trilling birdsongs to booming bass notes. We think this technology has the potential to illuminate their auditory worlds.

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