High-intensity artificial cartilage with a "magic" function similar to natural cartilage
Release date: 2017-11-21
Artificial cartilage is very flexible and tear resistant. Image source: University of Michigan
Cartilage is a very "magic" tissue in the body that has unparalleled liquid strength. In cartilage tissue, 80% of the ingredients are water, but it helps our body cope with very strong stress.
Synthetic materials are often difficult to compete with natural cartilage until researchers from the University of Michigan and Jiangnan University in China developed the “Kevlartilageâ€. This is a kind of aramid-based material. Aramid is a synthetic fiber. It is widely known that it is used in bulletproof vests, and its strength is evident. Another material is polyvinyl alcohol (PVA), a common material in hydrogel cartilage. This new blend of materials gives us unexpected surprises. It not only has very good strength, but also has a similar water content of natural cartilage, and is expected to be a good alternative to cartilage or other soft tissues in the body. The study was published in the recent Advanced Materials.
Cartilage has a very large clinical need. In the United States, 850,000 people need surgical resection or replacement of knee cartilage. People with many joint injuries will benefit from quality cartilage substitutes. Although other types of artificial cartilage are already undergoing clinical trials, these materials do not achieve the perfect combination of strength and water content.
Professor Nicholas Kotov, the research leader, said that the physical properties of other synthetic materials used to model cartilage determine that it does not have enough water to transport the nutrients that cells need to grow. At the same time, hydrogels can be designed with enough water to support the growth of chondrocytes, which build up natural cartilage. However, the strength of these hydrogels is not very good and they are easily torn.
Like natural cartilage, artificial cartilage relies on releasing moisture to withstand stress and then recovers by absorbing water. Image source: University of Michigan
In natural cartilage, a network of proteins and other biomolecules gains power through the flow of water in their cavities. The pressure from the water reconfigures the network to deform it without being destroyed. Water is released during this process, and the network is then recovered by absorbing water.
This mechanism allows the joint to withstand large impacts against external forces. For example, during knees, during the running, repeated exertion of force on the cartilage between the bones forces the water to flow out, making the cartilage softer. Then, when the runner rests, the cartilage absorbs water so that it can resist compression again.
Artificial cartilage has the same mechanism of releasing moisture under pressure and then absorbing water like a sponge. Nanofibers form the framework of the material, and when the material is exposed to stretching or compression, the PVA in the network captures moisture. Even 92% of the water version is comparable to cartilage, and 70% of the version achieves rubber elasticity.
Electron microscopic image of a synthetic cartilage matrix. Image source: University of Michigan
Because this mixed material does not harm nearby cells, Kotov expects this artificial cartilage to be a suitable implant in some cases, such as the depths of the knee. He also wondered if chondrocytes could grow in this synthetic network to produce a mixed cartilage.
Researchers feel that the potential application of this material is not limited to cartilage. They expect similar networks of mixed materials built at different scales and may be equally applicable to other soft tissues.
Reference material
[1] Kevlar-based artificial cartilagemimics the magic of the real thing
[2] High-Strength Artificial Cartilage Madefrom Kevlar
Source: Health New Vision (Micro Signal HealthHorizon)
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