Alexander Heckel

The world's smallest wedding rings are built up from two interlocked strands of DNA.

Thorsten Schmidt can now say he had a hand in creating the world's smallest wedding rings, measuring less than a thousandth of the width of a human hair.

The interlocked rings, known as catenans (after the Latin word for "chain"), were made from looped strands of DNA and measure just 18 nanometers wide. The wedding angle comes about not only because of the rings' perfectly circular shape, but also because Schmidt got married while he was working on the experiment.

These rings aren't just a romantic gesture: Because they're freely pivotable, they could be useful components in nano-machines or molecular motors.

"We still have a long way to go before DNA structures such as the catenan can be used in everyday items," Professor Alexander Heckel, Schmidt's co-author and adviser at Germany's Goethe University Frankfurt, said in a news release, "but structures of DNA can, in the near future, be used to arranage and study proteins or other molecules that are too small for a direct manipulation, by means of auto-organization."

Heckel and Schmidt / ACS Nano Letters

An atomic force miroscope image shows the interlocked DNA rings, along with an illustration showing how they're chained together.

The experiment, reported in the journal Nano Letters, involved creating two C-shaped DNA fragments that were positioned with their open ends pointing away from each other. Polyamide bonds were attached to the DNA to anchor the fragments to each other, and then the researchers added an oligonucleotide to close each of the C-sections and form the rings. The operation was done with mere chemistry. No nanometer-sized tweezers were required.

The paper notes that the assemblages resemble "stylized wedding rings," and here's the icing on the cake: Schmidt, who is now at Harvard's Wyss Institute for Biologically Inspired Engineering, dedicated the paper "to his wife and colleague Dr. Diana P. Goncalves Schmidt on the occasion of their wedding." Let's see Prince William top that one!

More tricks with twisty molecules:

• DNA folded into a world of patterns
• Slideshow: Making smiley faces from DNA
• DNA robots pave way for micro-factories
• The latest twist: Pretzels made of DNA
• Play a game and engineer real RNA

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