At the molecular level, glass is a liquid-like substance that lacks order in its molecular structure, but its mechanical properties are solid-like. Typically, glass is manufactured in a process called vitrification. Molten materials are rapidly cooled and allowed to set before they can crystallize, resulting in an amorphous state that allows unique optical, chemical, and mechanical properties. Researchers from Tel Aviv University (TAU) have created a type of glass that is formed spontaneously when a powdered substance comes into contact with water at room temperature. The glass is a strong adhesive, fully transparent, and has self-healing properties. It is expected to have applications in a broad range of industries, from satellite communications to medical fields. The researchers found that the aromatic peptide, which consists of a three-tyrosine amino acid sequence (YYY), forms a molecular glass spontaneously, upon evaporation of an aqueous solution, under room-temperature conditions. This creates a system that uniquely combines often contradictory sets of properties, such as high rigidity along with the ability to self-heal while in moist environments at room temperature. The peptide glass can be formed at room temperature when it comes into contact with water, displaying properties such as transparency, rigidness, adhesiveness, and the ability heal cracks while in a moist environment. Courtesy of Tel Aviv University. “Amino acids and peptides have a natural tendency to connect to each other and form ordered structures with a defined periodic arrangement, but during the research, we discovered a unique peptide that behaves differently from anything we know: it didn’t form any ordered pattern but an amorphous, disordered one, that describes glass,” said Ehud Gazit, a professor in TAU’s department of materials science and engineering. The peptide glass, said lead author Gal Finkelstein-Zuta, a PhD student in TAU’s Shmunis School of Biomedicine and Cancer Research, can be easily created by adding powder to water. The glass can be used to make lenses, not with conventional grinding and polishing, but by placing a drop of the solution onto a surface and controlling its curvature by adjusting the solution volume. According to Gazit, this is the first time that glass has been successfully created under simple conditions. But not less important are the glass' properties, he said. "On the one hand, it is very strong and on the other hand, very transparent – much more transparent than ordinary glass. The normal silicate glass we all know is transparent in the visible light range, the molecular glass we created is transparent deep into the infrared range." The researchers found that the glass is transparent in a wide spectral range from the visible light to the mid-infrared and is a strong enough adhesive to hold two microscope slides together while under a 5 kg load. Because of the glass’ resilience and multiple functions, the team believes it could be used in applications such as optics and electro-optics, satellite communication, remote sensing, and biomedicine. The research was published in Nature (www.doi.org/10.1038/s41586-024-07408-x).