Graphene Quantum Dots

Researchers at China's Hunan University, Chinese Academy of Sciences and the University of Washington in the U.S have developed a metal-free nanozyme based on graphene quantum dots (GQDs) for highly efficient tumor chemodynamic therapy (CDT).

GQDs have potential as a cost-effective means of addressing the toxicity concerns associated with metal-based nanozymes in tumor CDT. However, the limited catalytic activity of GQDs has posed significant challenges for their clinical application, particularly under challenging catalytic conditions. "The obtained GQDs, which are made from red blood cell membranes, are highly effective in treating tumors with few side effects," said Liu Hongji, a member of the research team. "One of the advantages is that they are metal-free. In addition, they function as excellent peroxidase-like biocatalysts."

A team of researchers from The Barcelona Institute of Science and Technology (ICFO) and Barcelona-based startup Qurv Technologies have designed flexible, nearly transparent graphene-enhanced image sensors that could be hidden in plain sight.

The sensors, based on graphene and quantum dots, could be integrated directly onto eyeglasses or curved windshields, placed right in front of a user’s eyes. This could make eye-tracking hardware less bulky, improve the accuracy of gaze detection, and reduce computational complexity, says Frank Koppens, who co-led the research and co-founded Qurv in 2020.

Researchers from Germany's RWTH Aachen University, Forschungszentrum Jülich and Japan's National Institute for Materials Science (NIMS) have found that bilayer graphene allows the realization of electron–hole double quantum dots that exhibit near-perfect particle–hole symmetry. Moreover, They showed that particle–hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade that will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.

Quantum dots in semiconductors such as silicon or gallium arsenide are considered great candidates for hosting quantum bits in future quantum processors. The recent study essentially shows that bilayer graphene has even more to offer than other materials. The double quantum dots the researchers have created are characterized by a nearly perfect electron-hole-symmetry that allows a robust read-out mechanism – one of the necessary criteria for quantum computing. 

Researchers from the University of California Santa Cruz, University of Manchester and Japan's International Center for Materials Nanoarchitectonics and National Institute for Materials Science have used a scanning tunnelling microscope to create and probe single and coupled electrostatically defined graphene quantum dots, to investigate the magnetic-field responses of artificial relativistic nanostructures.

Trapped electrons traveling in circular loops at extreme speeds inside graphene quantum dots are highly sensitive to external magnetic fields and could be used as novel magnetic field sensors with unique capabilities. Although graphene electrons do not move at the speed of light, they exhibit the same energy-momentum relationship as photons and can be described as "ultra-relativistic." When these electrons are confined in a quantum dot, they travel at high velocity in circular loops around the edge of the dot.

Malaysia-based graphite and single-layer graphene producer, Graphjet Technology (GTI), has partnered with Quantum Science (QS), a UK-based quantum dot and ink technology developer, to explore technical and commercial opportunities to develop a quantum dot and graphene-based materials device platform.

GTI, which is on its way to a listing on the Nasdaq Exchange following the merger with SPAC Energem Corp, will be responsible for the funding of the development of the platform. At the same time, QS is responsible for developing the platform. GTI expects to contribute up to five million pounds (over USD$5.7 million) towards the platform's development during the deal's term or around three years.

A recent study has reported the use of human host defense peptide-conjugated graphene quantum dots for the prevention of virus entry into host cells.

Research on the SARS-CoV-2 virus mainly focuses on the spike protein (S1) which contains the receptor-binding domain (RBD) and the binding of this to the angiotensin converting enzyme 2 (ACE2) receptor within epithelial cells enables the virus to enter host cells in humans. This research resulted in the spike protein becoming a target for vaccines that aimed to produce neutralizing antibodies against the S-RBD. But while this concept seemed useful, recent reports have suggested the mutations on the SARS-CoV-2 virus and specifically in the S-RBD, can cause a decline in the level of neutralizing antibodies against the delta (B.1.617.2) variant that may have been produced during a previous infection or from immunization via a vaccine.

Rice University researchers, in collaboration with teams at Oak Ridge National Laboratory, University of Saskatchewan, King Abdullah University of Science and Technology and CAS, have used graphene quantum dots (GQDs) to assemble what they say may transform chemical catalysis by greatly increasing the number of transition-metal single atoms that can be placed into a carbon carrier.

The process uses functionalized graphene quantum dots to trap transition metals for higher metal loading single-atom catalysis. Illustration courtesy of the Wang Group (from Rice Uni website)

The technique uses graphene quantum dots, 3-5-nanometer particles of graphene, as anchoring supports. These facilitate high-density transition-metal single atoms with enough space between the atoms to avoid clumping.

Qurv Technologies, a Spain-based startup established in 2020 to develop wide-spectrum image sensors based on graphene and quantum-dot technologies, has developed a sensor that combines the unique electronic properties of graphene with suitable quantum nanoparticles as light sensitizers. The new device reportedly enables efficient detection of a broad range of wavelengths from ultraviolet to infrared light all concentrated into one simple device.

The production and transfer process of graphene leverages existing scalable Complementary Metal Oxide Semiconductor (CMOS) manufacturing processes. Furthermore, this graphene-based sensor could replace traditional costly alternatives based on indium gallium arsenide, paving the way to SWIR imagers up to 1000 times cheaper.

Japan-based material developer Green Science Alliance developed a new composite material made from a combination of graphene quantum dots and silica, which could be useful for creating white LEDs from blue LEDs (440-470 nm).

The company says that this is the first adoption of such a material for LED applications. The company says the adoption of the QD and Silica offers superior performance to the currently-used phosphor as the QDs do not suffer from light scattering, and the white LED is more efficient. The material is also said to be inexpensive.

ZEN Graphene Solutions, in partnership with Professor Mohammad Arjmand, has announced the award of a CAD$780,000 (around USD$609,600) Alliance Grant - part from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the rest from a combination of cash and in kind contributions from ZEN).

Alliance Grants are awarded through a competitive peer review process, and this proposal, titled Synthesis of Graphene Nanomaterials and Development of Their Multifunctional Polymer Nanocomposites, is ZEN’s highest single monetary grant award from NSERC to date and supports NSERC’s growing interest in nanomaterials.