Eight-letter DNA uses hydrogen bonds just like natural DNA to link its two new pairs—S with B and P with Z—and the bases can appear next to each other.
https://singularityhub.com/2019/02/24/scientists-just-added-four-new-letters-to-the-genetic-code/
* added four new bases * bacteria to use this code * stable regardless of the sequence * new amino acids * admitted to Wired * long-term data storage * reliant on supplies of lab-created building blocks * life beyond Earth * told CNN * search for extraterrestrial life