Cellular surveillance: DNA-based recording to monitor and memorise biological events

Continuous monitoring of intra- and extra-cellular environments, ranging from open fields and rivers to within a single cell, is often limited by costly equipment, labour intensity or invasive techniques. It may, however, be possible to avoid these issues by developing a monitoring device on a much smaller scale. By applying novel synthetic biology techniques, it is now possible to engineer organisms with refined bio-recording capabilities, using DNA as a recording medium on which a cellular ‘memory’ of past events can be written. Through a variety of mechanisms, using recombinases, CRISPR nucleases, base editing, polymerases and prime editing, intra- and extracellular events can be recorded along with temporal, spacial and magnitude information. Here, the mechanisms developed for DNA-based bio-recording devices so far are assessed and discussed, within the context of the potential future applications of these devices.