Peptides With Unique Properties Can Assemble Into Rigid Glass and Heal if Cracked When Combined With Water [Study]

Peptides With Unique Properties Can Assemble Into Rigid Glass and Heal If Cracked When Combined With Water [Study]
(Photo: Wikimedia Commons/Willerth, S.M. and Sakiyama-Elbert, S.E)

A self-assembling peptide has been discovered, and it forms into a glass. It heals itself when cracked.

Self-Assembling Peptide With Unique Properties When Mixed With Water

In a new study, researchers discovered a peptide that may self-assemble into a rigid glass when combined with water. Peptides are chains of amino acids that resemble miniature forms of proteins.

Since they may self-assemble into structures with distinct characteristics, peptides are appealing chemical building blocks. These structures are typically crystalline in form; hence, they are not very useful if you want a glassy substance.

The glass needs a liquid-like structure without a crystal's regular, periodic pattern. To achieve this for conventional glass, the process requires melting and rapid cooling to lock the glassy structure before crystals can form.

However, a group of researchers found that a particular peptide will make peculiar interactions with water, enabling it to form a structure like glass while searching for something quite different. The peptide dissolves in water and spontaneously assembles into a glass. It works as the water forms bridges between the peptide molecules, stabilizing its amorphous structure.

The peptide glass is transparent across visible and infrared wavelengths of light and has a refractive index close to that of commonly used optical glasses. As the water in the solution evaporates, it tends to form curved shapes in the manufacturing process, making it easy to form into convex lenses. By adjusting the solution volume, the team could create different curvatures and, thus, different focal lengths.

Additionally, it's a strong adhesive due to the intermolecular hydrogen bond interaction that gives rise to its structure, allowing it to adhere to water-loving surfaces. The team even used it to glue two microscope slides, and they remained attached even under a 5-kilogram load.

Also, unlike conventional glass, the brittleness of the peptide glass can be modified by adding or removing water. Dehydrate it enough, and the glass will crack, but it can also heal itself without leaving any trace of the damage.

The spontaneous glass formation was unexpected, and the researchers were surprised when they observed it. The peptide glass is "recyclable, self-healing, optically transparent glass." Plus, it can act as a glue.

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What Are Peptides?

Peptides are chains of chemicals known as amino acids -- the "building blocks" of proteins. Peptides are essentially small proteins, ranging in length from 20 to 100 amino acids.

Peptide bonds hold the strings of amino acids that make up peptides and proteins. Though the terminology isn't used precisely, the key distinction is that peptides are shorter strings of amino acids than proteins. Most scientists define proteins as chains containing more than 100 amino acids.

Additionally, scientists refer to peptides larger than 20 amino acids as polypeptides and oligopeptides for peptides that are between 10 and 20 amino acids long.

Peptides have several applications. They can be used for anti-aging, applied to skin to heal wounds and fight bacteria, or used as supplements for muscle growth, hair growth, and weight loss. Researchers have also used peptides to make new materials like nanotubes and 3D scaffolds.