Joint research: Probing the mysteries of a surprisingly tough hydrogelMarch 12, 2008Some 46 million people suffer from arthritis in the United States alone. The worst cases require painful surgeries to drill holes in and reinforce joints. Now researchers working at the National Institute of Standards and Technology (NIST) are studying an unusually pliant yet strong synthetic cartilage replacement in hopes of providing arthritis victims with some relief. In a paper* presented at the March Meeting of the American Physical Society, NIST scientists and colleagues from Hokkaido University in Japan, reported on a gel that, while having the pliancy of gelatin, won't break apart even when deformed over 1,000 percent. By using NIST's neutron research facility to show how the molecules in the gel sustain such large deformations, the research team hopes to make it easier to design materials with even better mechanical properties. Known as double-network hydrogels, the incredible strength of these new materials was a happy surprise when first discovered by researchers at Hokkaido in 2003. Most conventionally prepared hydrogels-materials that are 80 to 90 percent water held in a polymer network-easily break apart like a gelatin. The Japanese team serendipitously discovered that the addition of a second polymer to the gel made them so tough that they rivaled cartilage-tissue which can withstand the abuse of hundreds of pounds of pressure. A combination of a brittle hydrogel and a soft polymer solution leads to a surprisingly tough material. Initial work using NIST's neutron scattering techniques to explore the structure of the gel found unexpected results. The two polymers** were attracted to each other-despite the fact that one polymer is negatively charged and the other neutral-and can withstand a certain force before they can be pulled apart. The total amount of force that can be endured by this polymer pair gets amplified enormously because there are many contacts along each long chain. Efficacy of stress transfer between the long added chain and gel network forms the cornerstone of the toughening mechanism in DN-gels. The latest paper discusses a molecular-level toughening mechanism proposed based on neutron scattering measurements that gather, in detail, how the two polymers behave when the gel is deformed. Under deformation, these two polymers arrange themselves into an alternating, well-ordered, periodic pattern that is repeated approximately every 2 microns. This periodic structure is a hundred times larger than what is usually seen in molecules under deformation and its formation elegantly dissipates a large amount of deformation energy to stabilize the gel from crumbling apart. Establishing the details of the molecular structure will allow for more precise design of the next generation of hydrogels that are tough and rigid at the same time. Real cartilage goes through a process of constant daily destruction and regeneration under everyday stresses; the researchers hope a good synthetic cartilage could endure year after year under the rigors of the body before needing to be replaced. National Institute of Standards and Technology (NIST) |
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| Related Hydrogel Current Events and Hydrogel News Articles 'Spaghetti' scaffolding could help grow skin in labs Scientists are developing new scaffolding technology which could be used to grow tissues such as skin, nerves and cartilage using 3D spaghetti-like structures. Micropatterned material surface controls cell orientation Cells could be orientated in a controlled way on a micro-patterned surface based upon a delicate material technique, and the orientation could be semi-quantitatively described by some statistical parameters. arrow researcher finds natural hydrogel helps heal spinal cord Research led by a scientist at the Barrow Neurological Institute at St. Joseph's Hospital and Medical Center has shown injecting biomaterial gel into a spinal cord injury site provides significantly improved healing. Proteins in gel Several thousand test fields are tightly packed together on the tiny surface of a biochip. They permit the rapid analysis of substances, e.g. for diagnosing allergens in the blood. Cutaneous application of nanoparticles offers hope for treatment of erectile dysfunction Cutaneous application of nanoparticles may offer a new means of delivering drugs to treat erectile dysfunction (ED), according to findings presented at the 104th Annual Scientific Meeting of the American Urological Association (AUA). Nanotech coating could lead to better brain implants to treat diseases Biomedical and materials engineers at the University of Michigan have developed a nanotech coating for brain implants that helps the devices operate longer and could improve treatment for deafness, paralysis, blindness, epilepsy and Parkinson's disease. Self-assembling nano-fiber gel delivers high concentrations of clinically approved drugs Two teams of scientists from Harvard-MIT Division of Health Science and Technology (HST) at Brigham and Women's Hospital have developed a new self-assembling hydrogel drug delivery system that is biocompatible, efficient at drug release, and easy to tailor. Hydrogels provide scaffolding for growth of bone cells Hyaluronic hydrogels developed by Carnegie Mellon University researchers may provide a suitable scaffolding to enable bone regeneration. The hydrogels, created by Newell Washburn, Krzysztof Matyjaszewski and Jeffrey Hollinger, have proven to encourage the growth of preosteoblast cells, cells that aid the growth and development of bone. Doctoral student Sidi Bencherif will present this research, Sunday, Aug. 17 at the 236th national meeting of the American Chemical Society in Philadelphia. 'Smart' materials get smarter with ability to better control shape and size A dynamic way to alter the shape and size of microscopic three-dimensional structures built out of proteins has been developed by biological chemist Jason Shear and his former graduate student Bryan Kaehr at The University of Texas at Austin. UD scientists invent novel hydrogels for repairing, regenerating human tissue University of Delaware scientists have invented a novel biomaterial with surprising antibacterial properties that can be injected as a low-viscosity gel into a wound where it rigidifies nearly on contact--opening the door to the possibility of delivering a targeted payload of cells and antibiotics to repair the damaged tissue. More Hydrogel Current Events and Hydrogel News Articles |
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