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Biomedical breakthroughs

Biomedical breakthroughs

A fluorescent material that is also nontoxic and biodegradable could help detect cancer in early stages as well as deliver drugs to combat the disease. The material uses naturally occurring building blocks like citric acid.

Jian Yang’s latest discovery sports the glow of success. The bioengineer has developed the first implant material of its kind that’s nontoxic (so it can be used in biomedicine), biodegradable (so it will have no long-term toxicity concerns), and has natural fluorescence (so it can be used as a biomarker or tag).

Funded in part by the National Institutes of Health/National Institute of Biomedical Imaging and Bioengineering, the research has the potential to revolutionize cancer therapy.

What we have here is an aliphatic biodegradable photoluminescent polymer (BPLP). To ensure that it would be useful in biomedicine, Dr. Yang, a bioengineering assistant professor, built his BPLP with naturally occurring building blocks, among them citric acid, octanediol, and nearly two dozen amino acids.

Jian Yang, bioengineering assistant professor

“With our polymer, you can do many things,” he says. “You can use it as an implant material. You can make our polymer into a bone-repairing template. You can use it for detection, tracking, and sensing applications. And since it’s degradable, it’s not a permanent implant. It will help the body heal; then when you don’t need it anymore, it’s gone.”

The leading edge of treating cancer is nanoparticles that transport drugs directly to cancerous cells, like tiny Trojan horses. It’s an effective treatment with few side effects. For Yang, it’s a starting point.

Because his BPLP glows brightly with an intrinsic fluorescence, using the polymer as a coating for drug-delivery nanoparticles would enable doctors to trace the path of the medicine within the body, making sure that it’s delivered on target. Further, doctors could monitor how scaffolding inside the body degrades, how tissue regenerates. Yang believes that his polymer gives physicians a universal way of knowing what’s going on inside their patients’ bodies.

It could also help in the early detection of cancer.

“One challenge in the surgical removal of cancer is that doctors can find the big tumors, but they cannot find the small cancerous areas as easily,” Yang says. “If you don’t remove those small cancer cell clusters, then you leave some cancer cells behind.”

“THE MATERIAL ITSELF IS FLUORESCENT, AND THIS IS UNIQUE. I THINK THIS IS A REVOLUTION IN BIOMATERIALS SCIENCE.”

In the body, a light shines on the BPLP and a bright glow results, ranging from blue to near infrared. Medical imaging machines then use this glow to produce a picture of the inside of the body and reveal things like previously unseen cancer cells.

So, thanks to Yang’s polymer, the same nanoparticles that deliver drugs to the cancer can also diagnose new cancers. He isn’t the first person to think of this, but he is the first to figure out how to make such intrinsically fluorescent implant polymers do both jobs. Previous researchers tried using organic fluorescent dyes, which are widely available but can be toxic. They’re also chemically unstable, so their signal gets gradually weaker.

Researchers turned to quantum dots, which are nanoparticles used in the fabrication of transistors, solar cells, LEDs, and lasers. Their fluorescence is stable and super bright. But quantum dots are made of metal, so they can poison the body as they decompose.

With Yang’s polymer, “we don’t have to use any of the dye, and we don’t have to use any quantum dots,” he says. “The material itself is fluorescent, and this is unique. None of the previous biodegradable polymeric implant materials can emit fluorescence without using an organic dye or a quantum dot. I think this is a revolution in biomaterials science.”

- Danny Woodward