Artificial cell membrane channels composed of DNA can be opened and locked with a key

Just as countries import a vast array of consumer goods across national borders, so living cells are engaged in a lively import-export business. Their ports of entry are sophisticated transport channels embedded in a cell's protective membrane. Regulating what kinds of cargo can pass through the borderlands formed by the cell's two-layer membrane is essential for proper functioning and survival.

source https://www.lifetechnology.com/blogs/life-technology-science-news/artificial-cell-membrane-channels-composed-of-dna-can-be-opened-and-locked-with-a-key