Graphene Oxide: Introduction and Market News - Page 42

Researchers developed a new way to detect protein-protein interactions using graphene. This kind of detection is used to monitor how a disease-related protein interacts with libraries of small peptides. The idea is to mix a tagged peptide with Graphene Oxide, which quenches the fluorescent signal from the pyrene-bound peptide when pyrene stacks onto its flat surface. Then, when adding the protein that needs to be tested you can find out whether it binds to the peptide by seeing whether the tagged peptide leaves the graphene oxide and the fluorescent signal returns.

Northern Graphite Corporation announced that they managed to produce graphene on a test basis using large flake graphite from the Company's Bissett Creek project in Northern Ontario. The company says that their large flake graphite was evaluated as a source material for making graphene by an eminent professor in the field at the Chinese Academy of Sciences who is doing research making graphene sheets larger than 30cm2 in size using the graphene oxide methodology.

The tests indicated that graphene made from Northern's jumbo flake is superior to Chinese powder and large flake graphite in terms of size, higher electrical conductivity, lower resistance and greater transparency.

Researchers from Seoul's National University developed a transparent and lightweight speaker made from Graphene. This may enable speakers embedded in windows or displays. It may be especially suited to develop noise-cancelling devices.

The graphene speaker was made by depositing graphene-oxide onto poly vinylidene fluoride (or PVDF) and then reducing it to create a graphene film (this is actually a new method to develop graphene films). So basically this speaker is made from PVDF sandwiched between two graphene electrodes. When an electrical current (from the sound source) is applied, the converse piezoelectric effect causes the PDVF film to distort - and thus sound waves are created.

Scientists from the University of Science and Technology of China in Heifei developed a simple and quick method of preparing "3D Graphene" in water - which they say can enhance Graphene so it is better suited to store hydrogen and act as a catalyst support in supercapacitors.

The scientists prepared the 3D graphene structures by self-assembly from graphene oxide using mild chemical reduction in water at 95 degrees Celsius (at atmospheric pressure) without stirring. The graphene shapes were controlled by using reactor vessels of differing shapes. The team were able to produce cylinder-, pear- and sphere-like shapes. The new materials features high electrical conductivity and high mechanical and thermal stability.

Researchers from Turkey's Bilkent University discovered that graphene oxide can be reversibly reduced and oxidized using electrical stimulus. They say that graphene's band structure can be electrochemically tuned in ambient air in a two terminal planar device (due to humidity in the air). The researchers claim that if this effect can be better controlled, you could use this to create E Ink like e-paper that will be ultrafast. This could also have applications in information processing.

Here's a video showing controlled reduction and oxidation in two-terminal devices (containing multilayer graphene oxide films):

Researchers from Vanderbilt University (Nashville, Tennessee) have developed a way to create a film of Graphene Oxide so it either causes water to bead up and 'run off' or alternatively be spread out in a thin layer. As graphene sheets are transparent, you can put this on your car's windshield and the water will shed so quickly that you won't need wipers. Or you can use it to make ships glide through water very efficiently. Or use it to make water repellent clothes or self cleaning glasses...

The team uses electrophoretic deposition to make Graphene - which is a wet technique that combines an electric field within a liquid medium to create nanoparticle films that can be transferred to another surface. The team found that they could change the manner in which the graphene oxide particles assemble into a film by varying the pH of the liquid medium and the electric voltage used in the process. One pair of settings lay down the particles in a rug arrangement that creates a nearly atomically smooth surface. A different pair of settings causes the particles to clump into tiny bricks forming a bumpy and uneven surface. The researchers determined that the rug surface causes water to spread out in a thin layer, while the brick surface causes water to bead up and run off.

Researchers from the Nankai University in china have developed a new drug delivery system that uses Graphene Oxide as the drug carrier. Graphene oxide has a very high surface area, enabling it to transport a large amount of the drug.

The team attached superparamagnetic Fe3O4 nanoparticles to the graphene oxide, which allows allows the carrier to be targeted to the tumor site by an external magnetic field.

Researchers from the University of Warwick has found molecular hooks on the surface of Graphene Oxide, that could potentially provide massive benefits to transmission electron microscopes.

Substance pivoting

The researchers also found an interesting property of these hooks - the molecules attached to them move and pivot around them.

Researchers in China and Japan have developed a graphene oxide based fluorescence assay for fast, ultra-sensitive, and selective detection of protein and demonstrated its use for detection of a prognostic indicator in early-stage cancer, cyclin A₂.

Although the researchers have managed to detect cyclin A₂ in their lab set-up with high sensitivity and specificity, this method still can not be applied to detect cyclin A₂ in clinical samples due to the trace amount of cyclin A₂ in the cell total protein. The team is trying to incorporate a signal amplification step to increase the output signal and detection sensitivity to solve this issue.

Researchers from Shanghai University has developed two water-based dispersible graphene derivatives that can effectively inhibit the growth of E.coli and have minimal toxic effects on harming cells (cytotoxicity). The two derivatives are based on graphene oxide (GO) and reduced graphene oxide (rGO).

The group tested the antibacterial properties of the GO sheets with E.coli DH5 cells via a luciferase-based ATP assay kit. After two hours incubation with the GO sheets of 20 µg/mL at 37C, the cell metabolic activity of the bacteria fell to around 70 per cent. With a GO concentration of 85 µg/mL, the activity of the E.coli cells fell to just 13 per cent suggesting a strong inhibition ability of GO nanosheets to E.coli, said the researchers.