Researchers at Northwestern University in Evanston have created a synthetic version of allomelanin, a pigment found in nature that can filter out harmful gases and pollutants from the air. Allomelanin is found in fungi cell walls and helps the fungi survive in harsh environments. However, its complete structure and properties have not been fully understood because it only exists in the environment in combination with polysaccharides and proteins. The synthetic version of allomelanin, made up of the same building blocks as the natural version, could help scientists better understand its properties.
The synthetic allomelanin is made up of porous mini-spheres that can absorb harmful gases and pollutants, making it a potential protective coating for clothing and masks. The research project was funded by the Defense Threat Reduction Agency and the Air Force Office of Scientific Research, and the practical applications of the synthetic allomelanin are particularly relevant for the military. The researchers were able to filter out ammonia gas, a mixture of carbon dioxide and methane, and toxic insecticides such as diazinon and paraoxon. They also tested the synthetic allomelanin with a chemical warfare agent analog, dimethylphosphonate, and found that it was able to absorb the gas.
The synthetic allomelanin is made from a known monomer of the fungal version called 1,8-dihydroxynaphthalene, which is oxidized with sodium periodate to form oligomers. These oligomers then form tiny spheres that create pores when methanol is added. The researchers were able to vary the structure of the spheres with additional chemicals. The synthetic allomelanin could potentially be used as a detoxifying agent, and its ability to slow down or even prevent gas permeation makes it a promising protective coating for clothing and masks.
