Graphene oxide (GO), a readily obtainable form of graphene in mass production, can have applications in biosensing.

In a recent development, scientists from the Fraunhofer institute in Berlin are modifying their GO sensors to test for COVID-19 antibodies. In recent work, they showed that a single drop of blood or saliva can be enough to accurately and reliably detect infection with other diseases within just 15 minutes. Disease detection is performed by a sensor that consists of a sheet of GO placed between two electrodes, functionalized with molecules that bind to a specific biomarker. The team is now gearing towards COVID-19 detection, a feat they expect to reliably achieve within the next year.

Image: Graphenea’s 1 tpa graphene oxide plant.

Graphene oxide has a history of being used for biosensing, including past work on antibody detection. Already in 2011, researchers showed that GO-modified carbon electrodes can be used in electrochemical immunosensors. These sensors were used to detect antibody-antigen interactions in rabbits. GO turned out to be an excellent electrode material for such electrochemical biosensors, yielding a very low charge transfer resistance.

Aside from disease detection from bodily fluids, GO has been used for breath detection. The ultrafast (<30 ms) response of GO devices to changes in humidity were utilized to detect human breath and whistling, as well as touchless user interfaces. The devices were made with a facile method on a flexible substrate, which opens avenues for use in wearable technology.

The advantage of GO as a biosensor is in its many defects. Typically a disadvantage for applications in high-speed electronics, defects in GO promote charge transfer and ease functionalization for detection of various analytes, which are both very advantageous for biosensing. Hence the material has been used for sensing a wide range of organic and inorganic molecules, which shows its use when mankind demands quick and reliable testing for the presence of a new disease, for instance.

GO can be produced in large quantities, for example in Graphenea’s 1 ton-per-year GO plant.