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Researchers from Brown University demonstrated a method of using graphene oxide (GO) to add some skeleton to the hydrogel material made of alginate, which is a natural material derived from seaweed and is currently used in various Biomedical applications.
In a paper published in the Carbon magazine, the researchers described a 3D printing method for making complex and durable alginate-GO structures that are harder and more resistant to breakage than using alginate alone.
"One of the limiting factors in using alginate hydrogels is that they are very fragile, and they tend to fall apart under mechanical loads or low-salt solutions.
" said Thomas Valentin, a PhD student in the Brown School of Engineering who led the research.
"What we showed Yes, by adding graphene oxide nanosheets, we can make these structures more robust.
”
The study shows that this material can also become harder or softer in response to different chemical treatments, which means it can be used to make "Smart" materials that react to the surrounding environment in real time.
In addition, alginate-GO retains the ability of alginate to repel oil, making the new material a strong antifouling coating.
The 3D printing used for manufacturing materials is called stereolithography.
This technology uses an ultraviolet laser controlled by a computer-aided design system to track patterns on the surface of a photoactive polymer solution.
Light binds the polymers together, forming a solid 3D structure from the solution.
Repeat the tracking process until the entire object is built layer by layer from the bottom to the top.
In this case, the polymer solution is made by mixing sodium alginate and graphene oxide flakes.
Graphene oxide is a carbon-based material that forms nano flakes one atom thick, which is stronger than steel.
One advantage of this technology is that the sodium alginate polymer is connected by ionic bonds.
These bonds are strong enough to hold materials together, but they can be destroyed by certain chemical treatments.
This enables the material to respond dynamically to external stimuli.
Previously, Brown’s researchers showed that this "ionic crosslinking" can be used to make alginate materials, which can be degraded as needed.
When a chemical substance is used to remove ions from the internal structure of the material, this material Will dissolve quickly.
For this new study, the researchers hope to understand how graphene oxide changes the mechanical properties of the alginate structure.
They showed that the hardness of alginate-GO can be twice that of alginate alone, and it is more resistant to cracking damage."The addition of graphene oxide allows the alginate hydrogel to bond with hydrogen bonds.
" said Ian Y.
Wong, Brown's assistant professor of engineering and senior author of the paper.
"We believe that the crack resistance is due to the fact that the cracks have to bypass the scattered graphene sheets, rather than being directly broken by a uniform alginate.
" The additional hardness allows the researchers to print out structures with overhangs, and alone It is impossible to use alginate.
In addition, the increased hardness does not prevent the alginate-GO ink from responding to external stimuli, just like alginate alone acts.
Researchers have shown that by immersing the material in a chemical that removes ions, the material expands and becomes softer.
When the ions are recovered by washing in an ionic salt, the materials restore their hardness.
Experiments show that by changing the external ion environment of the material, the hardness of the material can be adjusted to more than 500 times.
Researchers say that the ability to change its hardness allows alginate-GO to work in a variety of applications, including dynamic cell culture.
"You can imagine a scenario where you can image living cells in a rigid environment, and then immediately change to a softer environment to see how the same cells might react.
" Valentin said.
This may help to study how cancer cells or immune cells migrate between different organs throughout the body.
And because alginate-GO retains the strong oil resistance of pure alginate, the new material can be made into an excellent coating to prevent oil and other dirt from accumulating on the surface.
In a series of experiments, the researchers showed that the alginate-GO coating can prevent oil from contaminating the glass surface under high salinity conditions.
Researchers say this may allow alginate-GOG hydrogels to be used in coatings and structures used in marine environments.
"These composite materials can be used as sensors in the ocean to continuously read data during oil spills, or as an anti-fouling coating to help keep the hull clean.
" Wong said.
The extra hardness provided by graphene will make this material or coating more durable than alginate alone.
Researchers plan to continue experimenting with new materials, looking for ways to simplify production methods and continue to optimize their performance.
Source: Ai Tubang Public Account
In a paper published in the Carbon magazine, the researchers described a 3D printing method for making complex and durable alginate-GO structures that are harder and more resistant to breakage than using alginate alone.
"One of the limiting factors in using alginate hydrogels is that they are very fragile, and they tend to fall apart under mechanical loads or low-salt solutions.
" said Thomas Valentin, a PhD student in the Brown School of Engineering who led the research.
"What we showed Yes, by adding graphene oxide nanosheets, we can make these structures more robust.
”
The study shows that this material can also become harder or softer in response to different chemical treatments, which means it can be used to make "Smart" materials that react to the surrounding environment in real time.
In addition, alginate-GO retains the ability of alginate to repel oil, making the new material a strong antifouling coating.
The 3D printing used for manufacturing materials is called stereolithography.
This technology uses an ultraviolet laser controlled by a computer-aided design system to track patterns on the surface of a photoactive polymer solution.
Light binds the polymers together, forming a solid 3D structure from the solution.
Repeat the tracking process until the entire object is built layer by layer from the bottom to the top.
In this case, the polymer solution is made by mixing sodium alginate and graphene oxide flakes.
Graphene oxide is a carbon-based material that forms nano flakes one atom thick, which is stronger than steel.
One advantage of this technology is that the sodium alginate polymer is connected by ionic bonds.
These bonds are strong enough to hold materials together, but they can be destroyed by certain chemical treatments.
This enables the material to respond dynamically to external stimuli.
Previously, Brown’s researchers showed that this "ionic crosslinking" can be used to make alginate materials, which can be degraded as needed.
When a chemical substance is used to remove ions from the internal structure of the material, this material Will dissolve quickly.
For this new study, the researchers hope to understand how graphene oxide changes the mechanical properties of the alginate structure.
They showed that the hardness of alginate-GO can be twice that of alginate alone, and it is more resistant to cracking damage."The addition of graphene oxide allows the alginate hydrogel to bond with hydrogen bonds.
" said Ian Y.
Wong, Brown's assistant professor of engineering and senior author of the paper.
"We believe that the crack resistance is due to the fact that the cracks have to bypass the scattered graphene sheets, rather than being directly broken by a uniform alginate.
" The additional hardness allows the researchers to print out structures with overhangs, and alone It is impossible to use alginate.
In addition, the increased hardness does not prevent the alginate-GO ink from responding to external stimuli, just like alginate alone acts.
Researchers have shown that by immersing the material in a chemical that removes ions, the material expands and becomes softer.
When the ions are recovered by washing in an ionic salt, the materials restore their hardness.
Experiments show that by changing the external ion environment of the material, the hardness of the material can be adjusted to more than 500 times.
Researchers say that the ability to change its hardness allows alginate-GO to work in a variety of applications, including dynamic cell culture.
"You can imagine a scenario where you can image living cells in a rigid environment, and then immediately change to a softer environment to see how the same cells might react.
" Valentin said.
This may help to study how cancer cells or immune cells migrate between different organs throughout the body.
And because alginate-GO retains the strong oil resistance of pure alginate, the new material can be made into an excellent coating to prevent oil and other dirt from accumulating on the surface.
In a series of experiments, the researchers showed that the alginate-GO coating can prevent oil from contaminating the glass surface under high salinity conditions.
Researchers say this may allow alginate-GOG hydrogels to be used in coatings and structures used in marine environments.
"These composite materials can be used as sensors in the ocean to continuously read data during oil spills, or as an anti-fouling coating to help keep the hull clean.
" Wong said.
The extra hardness provided by graphene will make this material or coating more durable than alginate alone.
Researchers plan to continue experimenting with new materials, looking for ways to simplify production methods and continue to optimize their performance.
Source: Ai Tubang Public Account
