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creating & # 39; complicated structures, including & # 39 of the 3-D printing technique used to make the material permits; above, which mimics that atomic lattice grapheneCREDIT: Wong Lab / University Brow
Researchers Brown University have shown how to use oxine of grafil (GO) to add some backbone to a hydrogel material made from alginate, a natural material derived from algae currently used in & # 39; variety & # 39; biomedical applications. F & # 39; papers published in the journal carbon, Researchers describe a method & # 39; 3-D printing to make complex structures and long & # 39; GO alginate are much tougher and more resistant to breach the alginate alone.
"One factor limiting the use of & # 39; the alginate hydrogels is that they are very fragile – tend to fall apart under mechanical loading in & # 39; of & # 39; low salt solutions", said Thomas Valentin , PhD student at the School of Engineering & # 39; Brown who led the work. "What we have demonstrated is by nanosheets of & # 39; the oxide grafinu, we can make these structures more robust."
The material can & # 39; also becomes harder or softer with & # 39; response to various chemical treatments, which means it can & # 39; materials used to make "smart" to be able to respond to their surroundings in & # 39; real time, research shows. Moreover, alginate GO retains the capacity & # 39; the alginate to remove oils, and give potential & # 39; new material as a coating b & # 39; robust against cracking.
The 3-D printing method used to make the material is known as sterjolitografija. The technique using ultraviolet laser controlled by a & # 39; computer-aided design system to trace patterns on the surface of & # 39; fotoattiva polymer solution. The light causes the polymers together, and form solid structures & # 39; 3-D of the solution. The process & # 39; tracing is repeated until a whole is constructed with & # 39; layer by layer on bottom. F & # 39; in this case the polymer solution was made using & # 39; sodium alginate mixed with & # 39; sheets & # 39; oxine the beaker, a carbon-based material to form a nanoesoli & # 39; atom b & # 39; & # 39 b wall, his health are more b & # 39; health for pound than steel.
One advantage to the technique is that the sodium alginate polymer bound by & # 39; ionic bonds. The bonds are b & # 39; healthy enough to hold the material together, but can be shared with & # 39; certain chemical treatments. This gives the material the ability to respond with & # 39; dynamic way to external stimuli. Previously, the Brown researchers have shown that this "crosslinking ionic" can & # 39; is used to create alginate materials degrade upon request, dissolve quickly when treated with & # 39; chemicals that deter the decision of the internal structure material.
For this new study, researchers wanted to see how the grafinu oxide can & # 39; alter the mechanical properties of & # 39; the algin structures. They demonstrated that the alginate GO can & # 39; biennial hard as alginate alone, and far more resistant to failure by sharing.
"Adding & # 39; the oxine of grafinu stabilize hydrogel of & # 39; alginate with ties & # 39; hydrogen", said Ian Y. Wong, assistant professor & # 39 ; engineering & # 39; Brown and senior author of the paper. "We think that the fracture resistance is due to cracks that have spread around the interdixxiti graph graphite sheets instead of being able to break right though homogeneous alginate."
The extra stiffness enabled researchers to print structures were toppled parts, that would be impossible using & # 39; alginate alone. In addition, the increase in stiffness did not prevent the alginate also GO from reacting to external stimuli such as alginate alone. The researchers showed that by swimming materials in & # 39; chemical to remove its ions, the materials swell and become much softer. The materials regained their hardness when the decision was restored by swimming in & # 39; ionic imħal. The experiments showed that the hardness of the materials can & # 39; to be tuned on feature & # 39; 500 by varying their external ionic environment.
That ability to change its hardness can & # 39; do alginate useful in GO & # 39; & # 39 variety; applications, the researchers say, including dynamic cell cultures.
"You & # 39; imagine a scenario where you & # 39; c living cells image in & # 39; hard environment and then switch immediately to a softer environment to see how the same cell can respond", said Valentin. It can & # 39; to be useful in the study of how the cancer cells or the immune cells migrate through & # 39; various organs throughout the body.
And because the alginate GO maintains strong properties & # 39; algin pure alcohol oil repellents, the new material can & # 39; makes an excellent coating to keep oil and other grime to build up on surfaces. F & # 39; & # 39 series, experiments, researchers have shown that coating & # 39; GO alginate can & # 39; keep oil than of facing the glass surface in & # 39; & # 39 conditions; much salt water. It can & # 39; to make the alginate hydrogel GO useful for coating and structures used in & # 39; marine environments, the researchers say.
"These composite materials can be used as ocean sensors can keep reading over the oil spill, or as an antifouling coating which helps maintain clean the vessels' hulls, Wong said. The extra stiffness provided by the graphite making these materials or coatings much more sustainable than alginate alone.
The researchers plan to continue experimenting with new material, looking for ways to streamline its production and further improve its properties.
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