While some molecules are "chiral" and naturally exist in normal and reverse forms, life mostly guides things into one orientation: cell DNA twists rightward, for example. Viruses and enzymes have evolved to target life in those formats, so the prevailing theory is that manufactured mirror-image versions will resist attacks while still performing their intended functions.



Scientists have been making mirror images of DNA for years, so the Tsinghua researchers were able to order many parts of their experiment, but they did have to build their own reverse version of the DNA polymerase that coordinates copying, which drastically slowed down the process. That will need to speed up to make the process financially rewarding, but biochemical companies are already looking at the lucrative potential for mirror-image molecules, which could more efficiently operate inside the body without being degraded by enzymes that break down typically-oriented molecules.