Medical Metals

Researchers at North Carolina A&T State University are developing new materials that could revolutionize medical treatment. Right now, every metal that goes into the body goes in with the notion it will stay there forever, but NC A&T is developing smart implants, that would be absorbed by the body once their work is finished.

GREENSBORO - There’s a good chance you know someone who has been hospitalized for a medical issue that involved some type of implant. It could be a stent in an artery, or a rod, plate, or screw to help heal a broken bone. The U.S. Food and Drug Administration says tens of millions of Americans have implants.

In the next few years, medical care utilizing implants could be revolutionized because of groundbreaking research at North Carolina Agricultural and Technical State University, what everyone calls NC A&T. The university is in the forefront of the development of metallic bio-materials.

You could think of them as “smart metals” because when their job of helping to heal is completed, the metal dissolves in the body.

That’s right, no additional surgery needed. The metal simply dissolves. If it sounds like medical science fiction, it’s not. Initial research on the idea began in 2008.

“Think of it this way, when I was young and you broke a bone, you got a cast, and the cast stayed on and once it came off the bone was healed,” explains Dr. Boyce Collins, research scientist at NC A&T. “This is kind of an internal cast because you put the device in and once the bone is healed, you turn on the degradation process and the device goes away.”

That’s a far cry from the current medical practice, in which inserting a titanium rod into the bone often repairs broken bones. That implant holds the bone in place until it heals. Sometimes the implants are left in the body, however, often the devices are removed, which poses the risk of another surgery. It’s also expensive.

Researchers hope using magnesium, rather than titanium, may change the need to remove an implant. Magnesium is a metal, but it is also an essential nutrient that the body needs and knows how to metabolize.

Researchers are developing magnesium alloy implants. A magnesium alloy is a combination of magnesium and other metals.

However, there are many questions, including whether a magnesium alloy is strong enough to support healing, and how thick does an implant need to be? Scientists are placing tiny magnesium alloy chips into tubes containing chemicals that mimic the chemical condition of the human body to find out.

“We are testing the mechanical properties and corrosion property of this material,” says Dr. Zhigang Xu, a senior scientist at NC A&T. “So far we are finding the mechanical properties are enhanced, which is good news.”

There’s also the question of how much the magnesium implant would corrode. Would it last long enough to support the healing of the bone, or the opening of an artery using a coronary stent, which resembles a tiny basket in the shape of a long, narrow tube. Chris Smith, a graduate student reseacher, studies the corrosive properties of metal with an electron microscope. It turns out seeing the smallest of details gives you an insight into the bigger picture.

“This is a magnesium-calcium alloy,” says Smith. “This is the microstructure within the alloy and seeing it this close, in this much detail is really important in characterizing the alloy, because it gives you properties on corrosion, and the mechanical strength, things of that nature.”

Adding to the challenge of determining the properties of each magnesium alloy and how they will hold up in the body is that each implant must be custom made for a specific part of the body. In other words, an implant in the joint would face different forces than an implant in the shoulder or the hip.

“Every time you create a screw or a plate to repair a particular broken bone in the body, it needs certain properties,” says Dr. Jagannathan Sankar, Director of the National Science Foundation Engineering Research Center at NC A&T. “It has to have a certain strength when you pull it or push it. There is also the matter of its biodegradability and when it corrodes or dissolves, is there a problem with toxicity.”

Dr. Sankar says the ultimate goal of all of the research is to create what is called “material by design,” in which there is a mix of alloys that doctors can choose from, depending on what is needed for each patient. You could call it a customizable implant.

“The technology isn’t there yet,” says Dr. Sankar, smiling. “But the dream is becoming a reality. It’s a step-by-step process and we are working towards it.”


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