Video: Mucus inspires sticky, stretchy, antibacterial material

A new material that can function as an antibacterial adhesive or coating was inspired by a sticky substance found in nature: mucus. Mucus contains glycoproteins and water molecules linked together with hydrogen bonds. Researchers led by Xi Yao at City University of Hong Kong designed a substance that would mimic these chemical interactions while incorporating carvacrol oil, a compound derived from oregano that has antibacterial properties. They paired the oil with polyurea oligomers, which form hydrogen bonds with the carvacrol molecules similar to the way glycoproteins interact with water in mucus. Animals can alter the mechanical properties of the mucus they produce by secreting more or less water to dilute it. Similarly, the researchers can control the properties of their material by varying the carvacrol content, producing materials that range from a liquid-infused solid to a runny adhesive (ACS Appl. Mater. Interfaces 2020, DOI: 10.1021/acsami.0c00531). When used as a surface coating, the material can kill several kinds of bacteria within 15 min and remains effective for up to 70 days, even underwater, the researchers report. Early tests show the material doesn’t harm mammalian cells or red blood cells, suggesting potential biomedical applications. The researchers envision expanding this approach to other combinations of oils and oligomers.