After talking about the pacemaker which, once its function is over, dissolves, the medical biotechnology comes back to surprise us with a bone device, it too capable of self-dissolving once the lesion is cured. The intuition came to Xudong Wang, professor of materials science and engineering at the University of Wisconsin-Madison.
The study on the bone device was published in the journal Proceedings of the National Academy of Sciences .
Bone device: a remedy that opens the new frontiers of orthopedics
The continuous injuries of athletes from different parts of the world led Xudong Wang to wonder if it was possible to provide a new solution to make athletes recover as quickly as possible. The scholars involved in the research have assumed that electricity can help accelerate the healing of bones, except for fractures “zapping”Which instead require a surgical implant and the removal of electrodes powered by an external source.
From intuition, however, scientists moved on to the creation of a thin and flexible bone device is self-powered, implantable and bioabsorbable, so once the bone is sealed, the components of the device dissolve within the body.
The bone is a piezoelectric material, which means it produces a small amount of electricity when put under stress. These electrical discharges stimulate factors that promote bone growth and healing, which is why electrostimulation is an effective therapy.
While there are external stimulators that create an electric field to accelerate healing indirectly, the ideal solution is to directly stimulate the bone. Putting the device inside the body, however, has unique requirements, not the least of which is to power it, according to Wang: “The the ideal case is that the device generates itself, something that did not exist before“, Explained the scientist.
To create the new bone device with the supplement of the electrostimulation of the fracture, or FED, Wang and his group of experts started with a triboelectric nanogenerator, a thin-film device with microstructured surfaces that converts the mechanical energy produced by small movements into electrical energy. Experts paired the nanogenerator with a pair of electrodes to distribute the electric field to the bone. The developers have thus built these ultra-thin, biodegradable and bioabsorbable components on a substrate of poly (lactic-co-glycolic acid), a biocompatible polymer commonly used FDA approved.
The researchers’ initial tests confirmed that Small movements of the device actually created an electrical stimulation of around 4 volts, which it could sustain for over six weeks. They then tested the device on mice.
Animals implanted with the device fully recovered from a tibial fracture in about six weeks, much faster than animals in a control group. The mineral density and flexural strength of healed bones also reached the same level as healthy bones in animals that received electrical stimulation. After treatment, the devices degraded and absorbed into the rat bodies without complications and without the need for surgical removal.
Wang states that it is possible to fine-tune how long the stimulator will last inside the body, from weeks to months, by modifying the properties of the bioabsorbable material that covers the bone device. Eventually, the scientist would like to expand the fracture electro-stimulation device to work in humans. But for these self-powered devices, the power source can be a factor: “Generally, when someone has a fractured bone, they have to limit their movements “, the scholar specified.
In other words, someone wearing a cast may not produce enough mechanical energy to power the triboelectric nanogenerator: “The way a mouse moves provides constant stimulation for the device, but for a broken bone in a human that cannot be moved, this is a problem. “ Wang clarified.
However, the human body provides virtually infinite sources of motion that could power the fracture stimulation device if the fractured bone is to remain motionless. “We may need the device to respond to other types of internal mechanical sources, such as changes in blood pressure“, Continued the scientist, who is already looking to the future of the FED.
“It will be very interesting and of great impact to address the development from animals to humans”, he concludes: “Our continuous collaborations over the last decade have been very productive and highly synergistic“, he claims Cai, who worked with Wang to create a bandage that works on similar principles and an implantable weight loss device, among other projects. “The Wang group designs and manufactures many interesting devices and our group can test them in vivo in various small animal models for subsequent large animal studies and potential clinical translation. “