https://phys.org/news/2018-05-synthetic-molecular-codes-genes.html

Ganesh Pandian Namasivayam and Hiroshi Sugiyama of Kyoto University's Institute for Integrated Cell-Material Sciences and their colleagues fabricated a molecular code that mimics a key process that turns on genes in the body. The code targets histones, the proteins that are responsible for packaging DNA so that it fits inside a cell's nucleus.

An uncoiled the DNA strand would be about two metres long. To fit inside cells, DNA is tightly wrapped around histones. When histones undergo a chemical process called acetylation, an acetyl group is added to part of their structure. This loosens DNA's attachment to the proteins, which leads to gene activation.