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Green Electronic Polymer-Based Films Produced Using Protein Nanowires

An interdisciplinary team of researchers at the University of Massachusetts Amherst has developed a new group of electronic materials that may pave the way to a “green,” more sustainable future in biomedical and environmental sensing.

The researchers who led the research include microbiologist Derek Lovley and polymer scientist Todd Emrick.

They say their new study reveals it is possible to integrate protein nanowires with a polymer to create a flexible electronic composite material that preserves the electrical conductivity and distinctive sensing capabilities of protein nanowires. The results have been published in the journal Small.

Protein nanowires have a number of benefits over the carbon nanotubes and silicon nanowires in terms of their stability, biocompatibility, and potential to be altered to sense a broad range of chemicals and biomolecules of medical or environmental interest.

However, sensor applications require that the protein nanowires be added into a flexible matrix appropriate for manufacturing wearable sensing devices or other types of electronic systems.

Postdoctoral research Yun-Lu Sun, currently at the University of Texas at Austin, discovered the ideal conditions for integrating protein nanowires with a non-conductive polymer to produce the electrically conductive composite material.

He showed that although the wires are composed of protein, they are extremely durable and easy to make into new materials.

An additional advantage is that protein nanowires are a truly ‘green,’ sustainable material. We can mass-produce protein nanowires with microbes grown with renewable feedstocks.

The manufacture of more traditional nanowire materials requires high energy inputs and some really nasty chemicals.

Protein nanowires are thinner than silicon wires, and unlike silicon are stable in water, which is very important for biomedical applications, such as detecting metabolites in sweat.”

Derek Lovley, Lead Researcher

In their proof-of-concept work, the protein nanowires formed an electrically conductive network when added into the polymer polyvinyl alcohol.

The material can be treated with challenging conditions, such as heat, or extreme pH such as high acidity, that might be estimated to destroy a protein-based composite, but it continued to function well.

The conductivity of the protein nanowires fixed into the polymer changed radically in response to pH.

The electrically conductive protein nanowires are a natural product of the microorganism Geobacter found in Potomac River mud by Lovley over 30 years ago. Geobacter uses the protein nanowires to form electrical connections with other microbes or minerals.

This is an important biomedical parameter diagnostic of some serious medical conditions. We can also genetically modify the structure of the protein nanowires in ways that we expect will enable detection of a wide range of other molecules of biomedical significance.”

Derek Lovley, Lead Researcher

The scientists have now applied for a patent on the concept of a conductive polymer composed of protein nanowires.

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