University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
A 3-D rendering of a novel bone-fixing composite developed at the University of Connecticut. The composite is made of silk fibers and fibers of polylactic acid that are coated with fine bioceramic particles to add strength while maintaining flexibility. The biodegradable composite helps heal bones without the complications posed by metal parts.
Credit: Image courtesy of Bryant Heimbach/UConn
To facilitate repair, doctors may install a metal plate to support the bone as it fuses and heals. Yet that can be problematic. Some metals leach ions into surrounding tissue, causing inflammation and irritation. Metals are also very stiff. If a metal plate bears too much load in the leg, the new bone may grow back weaker and be vulnerable to fracture.
Seeking a solution to the problem, UConn professor Mei Wei, a materials scientist and biomedical engineer, turned to spiders and moths for inspiration. In particular, Wei focused on silk fibroin, a protein found in the silk fibers spun by spiders and moths known for its toughness and tensile strength.
The medical community has been aware of silk fibroin for a while. It is a common component in medical sutures and tissue engineering because of its strength and biodegradability. Yet no one had ever tried to make a dense polymer composite out of it, and that is what Wei knew she needed if she was going to create a better device for healing broken load-bearing bones.
Working with UConn associate professor Dianyun Zhang, a mechanical engineer, Wei's lab began testing silk fibroin in various composite forms, looking for the right combination and proportion of different materials to achieve optimum strength and flexibility. The new composite certainly needed to be strong and stiff, yet not so much so that it would inhibit dense bone growth. At the same time, the composite needed to be flexible, allowing patients to retain their natural range of motion and mobility while the bone healed.
After dozens of tests, Wei and Zhang found the materials they were looking for. The new composite consists of long silk fibers and fibers of polylactic acid - a biodegradable thermoplastic derived from cornstarch and sugar cane - that are dipped in a solution in which each is coated with fine bioceramic particles made of hydroxyapatite (the calcium phosphate mineral found in teeth and bones). The coated fibers are then packed in layers on a small steel frame and pressed into a dense composite bar in a hot compression mold.
In a study recently published in the Journal of the Mechanical Behavior of Biomedical Materials, Wei reports that the high-performance biodegradable composite showed strength and flexibility characteristics that are among the highest ever recorded for similar bioresorbable materials in literature.
And they could get even better.
"Our results are really high in terms of strength and flexibility, but we feel that if we can get every component to do what we want them to do, we can get even higher," says Wei, who also serves as the School of Engineering's associate dean for research and graduate education.
The new composite is also resilient. Large leg bones in adults and seniors can take many months to heal. The composite developed in Wei's lab does its job and then starts to degrade after a year. No surgery is required for removal.
Joining Wei and Zhang in the research were Bryant Heimbach, a Ph.D. candidate and materials scientist in Wei's lab; and Beril Tonyali, a UConn undergraduate pursuing a degree in materials science and engineering.
The team has already begun testing new derivatives of the composite, including those that incorporate a single crystalline form of the hydroxyapatite for greater strength and a variation of the coating mixture to maximize its mechanical properties for bones bearing more weight.
Colin Poitras | EurekAlert!
Machine learning methods provide new insights into organic-inorganic interfaces
04.08.2020 | Technische Universität Graz
Unusual electron sharing found in cool crystal
31.07.2020 | Nagoya University
An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.
Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...
Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...
“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.
Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...
An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.
Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...
Although no life has been detected on the Martian surface, a new study from astrophysicist and research scientist at the Center for Space Science at NYU Abu...
23.07.2020 | Event News
21.07.2020 | Event News
07.07.2020 | Event News
05.08.2020 | Physics and Astronomy
05.08.2020 | Health and Medicine
05.08.2020 | Earth Sciences