An engagement ring is not a simple decoration. And DNA is nanotechnological :)

The smallest wedding rings are built from DNALeonid Popov, Membrane

Experimenters from Goethe University in Frankfurt am Main managed to carve out two rings from DNA molecules, and even made them intertwine with each other, like a decoration at a wedding of bacteria. However, it was a gift for a real wedding.

The two record rings are 18 nanometers in diameter, so they can only be seen with an atomic force microscope (illustration by Goethe-Universität). Intertwined, they formed a structure called catenan (catenan, from Latin catena – chain). Experts consider this achievement to be an important step in DNA nanotechnology, a young discipline born at the junction of biology, physics, chemistry and materials science.

The self-assembly of large molecules and the ability of DNA to find complementary molecular pieces have been used more than once to build various nanoscale structures and devices from DNA. But mostly it was about rigid fixed systems. Rings from Goethe University can rotate freely under certain conditions. This makes them interesting candidates for the role of nodes of molecular nanomachines.

To build a catenan, the authors developed such sequences of nucleotides that provided the assembly of the desired "architecture" automatically. First, two fragments of DNA in the shape of the letter C were attracted to each other so that their open ends looked outward, and then two smaller pieces of DNA closed the two gaps.

The principle of creating the structure and the scheme of the finished sample
(illustrations by Thorsten L. Schmidt, Alexander Heckel / Goethe-Universität).

It is curious that while working on wedding rings from DNA, one of the authors of this project, Thorsten Schmidt, got married. He dedicated his work to his wife Diana, who appreciated the idea at the proper level, since she worked with her husband in the same laboratory (now Torsten moved to Harvard University, and, presumably, his wife followed him).

Details of the experience are described in an article in Nano Letters (Construction of a Structurally Defined Double-Stranded DNA Catenane) and a press release from Goethe University (The world's smallest wedding rings).

Portal "Eternal youth" http://vechnayamolodost.ru14.04.2011