Biologically infused graphene sensors

When the porphyrin molecule heats up it loses its outer-layer hydrogen atoms and can bond to the graphene sheet on a surface of silver. The resulting structure endows the graphene with new properties. Credit: Yuanqin He - Technical University of Munich
A team of researchers from the Technical University of Munich has succeeded in bonding porphyrins, an important biochemical group, to a graphene sheet. Porphyrins are protein rings which are part of chlorophyll, essential for photosynthesis in plants, and haemoglobin, which is responsible for conveying oxygen in animals’ blood. The researchers say the resulting hybrid structures could be used in the field of molecular electronics and in developing new sensors.

The technique involves growing a graphene layer on a surface of silver to use its catalytic properties. Then, under ultra-high vacuum conditions, porphyrin molecules are added. These lose the hydrogen atoms from their periphery when heated on the metal surface, and they end up joining to the graphene edges.

Researcher, Manuela Garnica Alonso, explained: “For the first time we have managed to covalently bond porphyrins to graphene edges without altering their worthwhile properties.”

The researchers used an atomic force microscope to characterise in detail the chemical structure of the molecules involved. With this tool they observed, for example, a metal being incorporated at the centre of the porphyrins, as well as the specific bond of gas molecules, such as carbon dioxide, without altering the properties of the graphene.

According to the researchers, this graphene ‘functionalisation’ technique could be extended to more molecules in the future, which would bond to various carbon nanostructures, like graphene nanoribbons, while also having potential in the development of electronic applications.

Author
Tom Austin-Morgan

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