News — reduced graphene oxide

Breast cancer is one of the most common cancers within the UK and it’s the most common cancer in women universally. According to Cancer Research UK, in 2015 23% of breast cancer cases reported were deemed preventable.  Researchers found that the gene BRCA1, a breast cancer susceptibility gene, is responsible for 80% of breast and ovarian cancer families. There has also been some correlation between having this gene and your susceptibility to pancreatic and colon cancers. Finding this link has been vital in aiding disease prevention. The biotechnology industry is working towards producing efficient devices to be able to detect this gene in order to prevent and reduce the mortality risk.

The use of graphene oxide in biosensors has been growing exponentially due to the highly useful specifications of GO.  Shahrokhian and Salimian successfully produced a graphene oxide coated carbon electrode for DNA probe immobilisation, which was found to be more efficient than current electrodes used for this purpose. The GO layer on the electrode allows for bonding, via an amide bond, to the DNA which makes it an ultrasensitive detector. 

To ensure this method of DNA analysis is fast and simple, Shahrokhian and Salimian applied electrochemical reduction methods, which in turn produced rGO on the electrode surface.  As the graphene oxide has a larger accessible surface area, it accelerates the electron transfer process, enhancing the conductivity of the electrode.

By adding graphene oxide to the coating on the electrode, researchers were able to produce a highly sensitive biosensor. The properties of GO make it ideal for this area of research and the flexibility of being able to tune the GO properties specific to the research purpose, make it highly applicable in biotechnology. 

The range of graphene based materials in current research by academic groups around the world highlights the effect that they will one day have on day to day applications. If you have any enquiries about the applications of graphene oxide or how it can improve your existing applications, please get in touch and one of the GOgraphene team will be happy to help.

Sensors and Actuators, B, 2018, 266, 160-169

Many people see the development of ‘smart homes’ as the advancement of technology that can be controlled via your phone or other smart devices, however less attention is given to safety devices around the house. There has been significant research into incorporating graphene oxide in smart homes in applications from the internet of things to smart-curtains, but not as much has been found to improve upon household safety. There has been some investigations into graphene oxide as a smoke suppressant however. Researchers at the Shanghai Institute of Ceramics have recently developed a multi-purpose wallpaper that is simultaneously fireproof as well as containing built in fire detection systems using graphene oxide. In traditional homes, wallpaper is flammable and aids the spread of fires around the room, therefore there is an inherent need to minimise this risk. Previous attempts at creating flame retardant wallpapers have been somewhat effective, but the development has been hindered due to toxicity and environmental concerns.

Hydroxyapatite (Ca₁₀(OH)₂(PO₄)₆) nanowires have been utilised as a flame-retardant paper. Graphene oxide ‘ink’ is then used as a thermosensitive sensor, and acts as the wiring in a normal circuit connected to a lamp as well as a buzzer. In its normal form graphene oxide acts as an insulating material, but once exposed to high temperatures (such as a fire) the material is reduced with rapid deoxygenation and becomes electrically conductive and completes the circuit to alight the alarm lamp and sound the buzzer.

The range of graphene materials in current research in academic groups around the world highlights the effect that they will have on day to day applications in the near future. If you have any enquiries about the applications of graphene oxide or how it can improve your existing applications, please get in touch and one of the GOGraphene team will be happy to help.

Scientific Reports, 2018, 8, 3687

Mater. Today, 2014, 17, 152-153.

Environ. Int., 2003, 29, 665-682.

How soon could it be before graphene materials are present in everyday clothing? The rapid development of nanoscience has accelerated the production of miniaturised electronic devices. These advancements have opened new markets in the textile industry, with academics now researching wearable electronics via the weaving of conductive nanomaterials into the clothing fibres. These fibres have been demonstrated as strain and pressure sensors for health applications, wearable energy converters that can harvest solar energy, and as energy storage devices. This last application is particularly exciting as this will allow for displays on clothing, paper like mobile phones and clothing that can be used as a power source for when you’re on the move.

Materials such as metallic nanoparticles and polypyrrole have been deposited on yarn to produce supercapacitors with energy storage properties, however research has demonstrated issues with low strength and capacitance in the fibres. An ASC Nano published paper has utilised graphene oxide as an effective component in these fibres to increase the electronic performance. This research produced a fibre with high specific capacities, good flexibility and long cycle life, with up to 92% retention of capacity after 4950 cycles.

In the study, the yarn is coated in a graphene oxide dispersion and is easily reduced in-situ during the fibre making process. The reduced graphene oxide was found to increase strength, improve charge transfer to the metallic nanoparticles and also contributes to capacitance enhancement. This research exhibits another example of how graphene oxide can be used in composites to increase a products performance in a wide range of applications. If you have any questions regarding the use of graphene oxide in your research, please get in touch.

ACS Nano, 2015, 9, 4766–4775

Graphene oxide is part of the graphene family – two dimensional materials based on a honeycomb framework of carbon atoms. While graphene is pure carbon, graphene oxide has a series of oxygen functionalities decorating the surface of the honeycomb carbon structure. The oxygen functional groups can be complex, often containing alcohol, acid and epoxy units.

The presence of oxygen groups leads to significantly different properties when comparing graphene and graphene oxide. For example, graphene oxide can disperse easily in water, while graphene will not disperse. This is because the oxygen groups make graphene oxide a hydrophilic material, allowing water molecules to intercalate between the layers, separating them and forming a stable dispersion. As graphene is a hydrophobic material, this does not occur when trying to disperse graphene in water.

Another interesting difference between graphene and graphene oxide are their conductive properties, in terms of both thermal and electrical conductivity. While graphene has exceptionally high conductivity, graphene oxide is considered an insulator. Both materials have the same carbon framework, and as such the difference in functionality is directly related to the presence of the oxygen groups. The lower the oxygen content in graphene oxide, the higher the conductivity of the material.

There are some instances where the dispersion characteristics of graphene oxide are needed, but the properties of graphene are more relevant. In these instances, it is sometimes possible to convert graphene oxide into a material more similar to graphene in situ. This is done by reducing the graphene oxide, either chemically or thermally, to leave reduced graphene oxide. Reduced graphene oxide has a significantly lower oxygen content than graphene oxide, resulting in properties much closer to those of graphene. Reduced graphene oxide is distinguished from graphene because it will not have a pristine surface – the removal of oxygen groups usually leaves some defects on the surface, including some remaining oxygen functionality. For many applications, the surface of reduced graphene oxide is appropriate for yielding the desired functionality, in other instances the defects can lead to new, different properties for the material which make it interesting in its own right.

For more information on graphene oxide and how it could be of use for your research, please get in touch and a member of our team will be happy to discuss your work.

The GOgraphene Team have been investigating how to reduce graphene oxide to rGO

The GOgraphene team believe that understanding graphene oxide is the key to finding suitable applications. For many applications, the properties of reduced graphene oxide rather than graphene oxide are required by the user. It is well known that graphene oxide can be reduced through either chemical or thermal treatments, however the GOgraphene team wanted to obtain their own data. Considering the thermal reduction of graphene oxide, the GOgraphene team decided to investigate how to reduce their graphene oxide.

A small sample of graphene oxide flake was placed in a convection oven at 200 °C and left for 15 minutes. The material removed from the oven was visually different from the graphene oxide flake used. The relatively even size distribution of brown/amber coloured graphene oxide discs had become black, with variable shapes and sizes observed.

XPS analysis was conducted to determine how much the oxygen content within the material had dropped by. The graphene oxide flake used had an oxygen content of 21.2% before thermal treatment and 12.9% after treatment. This coincides well with the TGA (thermogravimetric analysis) carried out on GOgraphene’s graphene oxide flake which shows multiple decomposition steps when analysed between ambient and 1000 °C. Based on the TGA data, to achieve full reduction the GOgraphene team would predict that the sample would need to be heated to 350 – 550 °C.

In the future, the GOgraphene team intends to continue the investigation of thermal reduction of graphene oxide to rGO (reduced graphene oxide), with the intention of understanding how low the oxygen content can be driven. The team will also expand their work to examine chemical reductions, which in some applications may be more suitable than thermal reduction. In the meantime, the GOgraphene team hope that those interested in learning more about how to reduce graphene oxide find this latest news both interesting and useful. If you have any questions, please get in touch.