The idea of creating porous selective products has captured the attention of chemists for decades. Now, new research from Northwestern University shows that fungi may have been doing this just for millions of years.
When Nathan Gianneschi’s laboratory began synthesizing melanin that would be similar to those created by specific fungi known for living in strange, hostile environments including vessels- spacecraft, washing machines and even Chernobyl, did not initially expect the materials to be highly porous – a building that enabled the material to store and capture molecules.
Melanin has been found throughout living organisms, on our skin and behind our eyes, and as a pigment for many animals and plants. It also plays a role in protecting species from environmental stress. Strips of sea snakes with turtles darken, for example, in the presence of polluted water; moths that live in industrial areas turn black as their cells absorb toxins in soot. The researchers questioned whether this type of biomaterial could be made more like a sponge, to maximize these properties. And, in turn, did sponge-like melanins already exist in nature.
“Melanin’s function is not known all the time and in all cases,” said Gianneschi, the corresponding author of the study. “It is definitely a radical scavenger in human skin and protects against UV damage. Now, through synthesis we have come across this interesting substance that may be in nature. Fungi may make this material to add mechanical strength to their cells, but it is porous, allowing cross-feeding. “
The study will be published on Friday, March 5, in the Journal of the Chemical Society of America.
Gianneschi is Jacob and Rosaline Cohn Professor of Chemistry at Weinberg College of Arts and Sciences. With positions in the departments of materials science and biochemical engineering at the McCormick School of Engineering, Gianneschi is also an associate director of the International Institute for Nanotechnology.
The ability to create this material in a laboratory is inspiring for a number of reasons. In normal non-polar materials, particles adorn only on the surface. But porous substances like allomelanin awaken and retain undesirable toxins while letting good substances like air, water and nutrients through. This can allow manufacturers to create a breathable protective cover for clothing.
“You’re always excited about discovering something that might come in handy,” Gianneschi said. “But there is also an interesting idea that by finding out this, there may already be more such substances in biology. There are not many examples where chemical synthesis leads to the discovery of bio- It ‘s usually the other way around. “
Naneki McCallum, a graduate student researcher in the laboratory and the first author of the paper, had noticed that melanin was empty under the right conditions, or they could suggest that there would be gaps empty with an electronic microscope. When the team came across the synthetic material, they started experimenting with the contamination and selectivity of the materials for advertising molecules in these gaps.
In a major demonstration, the team, working with researchers at the Naval research laboratory, was able to demonstrate that the new porous melanin would act as a protective coating, preventing zero gas signals from getting through. Stimulated by this result, they then separated naturally occurring melanin from fungal cells. This was done by shrinking biomaterial from the inside, leaving a shell containing melanin. These structures are called “fungal ghosts” for their “Casper-like” quality similar shape. The material, which comes from fungi, can also be used as a protective coating in clothing. Surprisingly, the substance breathes, allows water to pass through, and traps toxins.
Another advantage of this material is its simplicity, as it is easy to produce and scale from simple molecular precursors. In the future, it could be used to make protective masks and face shields and has the potential for applications in long-distance space flight. Covering material in space allows astronauts to release toxins they emit while protecting themselves from harmful radiation, creating less waste and pressure.
It is also a step towards organ selection, a complex field of study that aims to absorb fertilizers such as water and allow healthy minerals to pass through while blocking heavy metals such as mercury.
“Fungi can thrive in places where other organisms are struggling, and they have melanin to help them make it,” McCallum said. “So we ask, what features can we use by reproducing such materials in the laboratory?”
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The study was supported by MURI through the Air Force Office of Scientific Investigation (AFOSR FA9550-18-1-0142) and the Defense Risk Reduction Group (HDTRA1-19-19-1-0010).
The title of the paper is, “Allomelanin: A Biopolymer of Intrinsic Microporosity.”
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