Graphene derivatives… different materials?
Graphene has a rich chemistry leading to derivatives which are crucial for its application in diverse fields.[1] Two widely studied derivatives are graphene oxide (GO) and reduced-graphene oxide (rGO). GO has diverse oxygen functional groups on its surface which endow high dispersibility in water and allow graphene to be coupled to (bio)molecules, expanding the diversity of its biomedical and many other applications. GO is insulating, but its reduction to rGO restores to a great extent its conductivity, accompanied with a decrease in solubility and content of chemical functional groups. Thus, modifying the properties of graphene through its derivatives is a key-enabling strategy for its processing and integration in practical systems, as for example in electrochemical[2] and FET biosensors[3].
Τhe high transconductance, stability, mechanical flexibility, and biocompatibility[4] offer a unique set of features for high-quality biosensors even under the most demanding environments such as whole blood.
Enriching 2D-BioPAD biosensors
An essential ingredient for a state-of-art advanced graphene biosensor (both in electrochemical and FET set-ups) is the tailored and reproducible chemical functionalization of graphene’s surface. This is because this surface functionalisation is indispensable for the effective and selective recognition of the target analytes (ions, nutrients, proteins, genes,or viruses in the samples), which in turn defines signal generation selectivity and, in some cases, ultra-high sensitivity.
This can be achieved via the chemistry of fluorographene (FG, pioneered by UP-CATRIN in 2010[5]), affording tuneable graphene derivatives (Figure 1)[6] without the need of harsh reaction conditions.
This functionalisation approach leads to graphene derivatives which combine a high density of surface functional groups (i.e. high functionalization degree), control over the type of the groups, while avoiding turning these derivatives into insulators. This strategy promotes the specific binding with bioreceptors/biorecognition units, and it can enhance the electrochemical activity[7], improving the signal-to-noise ratio, the selectivity and sensitivity of the devices, and ultimately the final biosensing reading.
In 2D-BioPAD, Palacky University Olomouc (UP)-Czech Advanced Technology and Research Institute (CATRIN), offers a cutting-edge solution for the design and synthesis of such tailored graphene derivatives. Their technology offers a design that eliminates the need for lengthy linkers and optimizes electron transfer on the biosensors.
Check out our website to learn more about this technology.
Figure 1. Fluorographene chemistry - pioneered and established by UP-CATRIN - leading to selectively and densely functionalized graphene derivatives, tailored for high electrochemical activity.
[1] Matochová D, et al. 2D chemistry: Chemical control of graphene derivatization. The Journal of Physical Chemistry Letters. 2018 Jun 11;9(13):3580-5.
[2] Wang, M, et al. A Wearable Electrochemical Biosensor for the Monitoring of Metabolites and Nutrients. Nat. Biomed. Eng 2022, 1–11.
[3]Xue, M., et al. Integrated Biosensor Platform Based on Graphene Transistor Arrays for Real-Time High-Accuracy Ion Sensing. Nat Comm 2022, 13 (1), 5064.
[4]Georgakilas, V., et al. Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications. Chem. Rev. 2016, 116 (9), 5464–5519.
[5] Zbořil, R., et al. Graphene Fluoride: A Stable Stoichiometric Graphene Derivative and Its Chemical Conversion to Graphene. Small 2010, 6 (24), 2885–2891.
[6]Bakandritsos, A., et al. Cyanographene and Graphene Acid: Emerging Derivatives Enabling High-Yield and Selective Functionalization of Graphene. ACS Nano, 11 (3), 2982–2991, 2017.
[7] Flauzino, J. M. R., et al. Label-Free and Reagentless Electrochemical Genosensor Based on Graphene Acid for Meat Adulteration Detection. Biosensors and Bioelectronic, 195, 113628, 2022.
