Protein plus graphene equals enzyme detecting paper

Earlier this year, a group of researchers grew their own circuitry using proteins found in milk, mucus and blood. In a similar vein, scientists in Switzerland have announced work on layering proteins with graphene to create a new kind of conductive paper.

In a paper in the May 6th issue of the journal Nature, the researchers from ETH Zurich’s Food & Soft Materials Science lab explain how they used traditional paper making techniques to build their new hybrid material; layering graphene with proteins and drying the mix in thin sheets.

The methodology is straightforward, according to Phys.org. The protein, in this case, beta-lactoglobulin, a milk protein, is first denatured by high temperatures in an acidic solution. The end-products of this denaturation process are protein fibrils suspended in water; these fibrils then act as stabilizers for the hydrophobic graphene sheets and allow them to be finely dispersed in water and processed into nanocomposites by a simple filtration technology.

Different proportions of protein and graphene in the mix change the properties of the paper. For example, more graphene means the material will be more conductive, while more protein fibrils produce a more absorbent material that responds quickly to changes in humidity. (Interestingly, the material has shape memory and when it dries out will return to its original shape.)

ETH professor Raffaele Mezzenga told Phys.org: "This combination of different materials with uncommon properties produces a novel nano-composite with some major benefits. The most interesting feature is that we can use this material as abiosensor to precisely measure the activity of enzymes."

This is because enzymes break down the protein fibrils, causing the resistance of the material to change. In theory, using different proteins would allow researchers to test the activity of different kinds of enzymes, too.