Graphene, a two dimensional material made of a layer of carbon exactly one atom thick, has a variety of interesting properties. When used as a field-effect transistor, it can detect slight physical forces applied to its surface, making it particularly useful for diagnostics where targets are microscopically small. Researchers at Osaka University in Japan have now harnessed this feature of graphene to detect bacteria at very low concentrations, including H. pylori which is known to cause stomach ulcers.

They created a new biosensor that uses microfluidics to position tiny droplets of a sample on top of a graphene component. The graphene was covered with antibodies meaning that the target bacteria would adhere and stay near it. However, because the antibodies prevented the bacteria from touching the graphene sensor, it couldn’t measure them directly, and a complementary technique was necessary.

The team figured out that by adding a chemical with which the target bacteria can interact and produce a byproduct, the sensor would be able to detect the presence of that byproduct. The graphene could detect the relevant compounds and even their concentrations in real time, providing a way to diagnose and then monitor the progression of various bacterial diseases.

Study in journal Nano Letters: Electrical Biosensing at Physiological Ionic Strength Using Graphene Field-Effect Transistor in Femtoliter Microdroplet

Via: Osaka University

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