Scientists recently tied the smallest, tightest knot ever recorded, containing just 54 atoms. The microscopic twist is in the form of a trefoil, the simplest type of nontrivial knot, with three interlaced crossings and no loose ends. The newly formed "metallaknot" contains gold and even assembles itself, according to a new paper published Jan. 2 in the journal Nature Communications.
The scientists discovered this double-record-breaking knot unintentionally, study co-author Richard Puddephatt, a chemist at the University of Western Ontario, told New Scientist. Originally, the researchers were trying to connect carbon structures to gold acetylides — a class of chemical compounds. During this process, one of the reactions yielded a golden chain that tied itself into a tangle resembling a three-leaf clover.
"It's quite a complicated system and, honestly, we don't know how it happens," Puddephatt said.
Along with being exceedingly tiny, the knot was also the tightest ever tied, according to the study. Knot tightness is measured by its backbone-to-crossing ratio (BCR), with the smallest value representing the tightest knot. The previous record holder for tightest knot had a BCR of 24, but this new trefoil just edges it out with a BCR of 23.
"Molecular knots, whose synthesis presents many challenges, can play important roles in protein structure and function as well as in useful molecular materials, whose properties depend on the size of the knotted structure," the researchers wrote in the study.
For example, knot structures are crucial for binding together DNA, RNA and proteins that the human body depends on. Trefoil knots, in particular, are fundamental in knot theory because they are the only tangles with just three crossings and can be built upon when combined with other knots. Unraveling the mysteries of knots could also have real-world applications, from building more effective plastics to creating new types of chemotherapies.
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Kiley Price is a former Live Science staff writer based in New York City. Her work has appeared in National Geographic, Slate, Mongabay and more. She holds a bachelor's degree from Wake Forest University, where she studied biology and journalism, and is pursuing a master's degree at New York University's Science, Health and Environmental Reporting Program.