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DNA-functionalized graphene sensor for breath analysis

(Nanowerk News) Reporting their findings in Advanced Functional Materials ("Humidity-Tolerant Single-Stranded DNA-Functionalized Graphene Probe for Medical Applications of Exhaled Breath Analysis"), researchers in Korea have demonstrated the enhanced sensing ability in a high humidity atmosphere of graphene sensors functionalized by single-stranded DNA, and proposed their novel sensing mechanism.
The device was constructed in a cost-effective manner by incubating graphene sensor platforms in droplets of the ssDNA solution, where ssDNA molecules were immobilized on top of the graphene via π-π stacking interaction.
Schematic illustration of the synthetic process for functionalizing graphene on an SiO2/Si substrate with ssDNA molecules.
Schematic illustration of the synthetic process for functionalizing graphene on an SiO2/Si substrate with ssDNA molecules. (© Wiley-VCH Verlag) (click on image to enlarge)
The team investigated the modulation of carrier density in the active graphene channel via electrostatic interaction with overlaying ssDNAs. They found that the single-stranded DNA-functionalized graphene (ssDNA-FG) sensors exhibit highly sensitive responses for amonia (NH3) and hydrogen sulfide (H2S) vapors, with the low detection limit of 103 ppb and 5.3 ppb, respectively, in a high relative humidity atmosphere.
These results show that the enhanced sensing ability is attributed to the effective modulation of not only the carrier density in graphene through negative-potential gating, but also the formation of an additional ion conduction path for proton hopping in the layer of H3O+ around ssDNA molecules.
By using principal component analysis (PCA), the researchers showed that ssDNA-FG sensor arrays can distinguish the halitosis and kidney disorder cancer related biomarkers, H2S and NH3 vapors, respectively.
Although this study is at a rather fundamental level, by focusing on simple cases of combinations of graphene and ssDNA molecules, the scientists succeeded in effectively demonstrating enhanced chemical vapor sensing at high humidity.
"Considering its selective vapor sensing capability in a high humidity condition, we expect that ssDNA-FG will provide a promising sensing platform for an inexpensive and noninvasive diagnostic tool to monitor halitosis and kidney disorder," the authors conclude their report..
Michael Berger By – Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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