In grad school, I (briefly) researched synthetic DNA logic gates. Using these, you can build neural networks in DNA [1] and probabilistic switching circuits (my co-authored paper) [2].
To do this, you design DNA strands that bind to each other in designated regions when mixed.
To make a logic gate, you just make some bindings conditional on other bindings. To detect that the gate is closed, you make the final binding uncover a fluorophore, which is detectable by a machine. (This is all called a *displacement cascade*.)
Using our techniques, the DNA bindings could not be undone. However, I imagine that a source of new DNA strands to replenish the old would effectively implement re-callable functions.
Fascinating. Have you read the story story, The Moral Virologist? I've always been curious as to how close to realistic it was, and you seem a person that could answer that.
To do this, you design DNA strands that bind to each other in designated regions when mixed.
To make a logic gate, you just make some bindings conditional on other bindings. To detect that the gate is closed, you make the final binding uncover a fluorophore, which is detectable by a machine. (This is all called a *displacement cascade*.)
Using our techniques, the DNA bindings could not be undone. However, I imagine that a source of new DNA strands to replenish the old would effectively implement re-callable functions.
[1] Neural nets in DNA: http://qianlab.caltech.edu/nature10262.pdf
[2] Probabilistic switching circuits: https://www.pnas.org/doi/full/10.1073/pnas.1715926115