Around a year ago these bots were tested in cockroaches. The DNA bots were made so when they come in contact with a protein, they unravel. If the DNA was carrying a certain molecule that was meant to destroy a cancerous cell for example, when the DNA came into contact with that cell, it would unravel, releasing the cancer killing molecule with it thus destroying the cancerous cell. The bots were labeled with fluorescence to track them. The results of the experiment proved the accuracy of these bots for finding and destroying a molecule that meant to harm the cockroaches. Researchers are hoping to implement these nanobots into humans in the near future.
The Accuracy Comparable to a Computer Processor
Although Nanobot technology is fairly new, it has technologically advanced in a multitude of ways.
Preliminary Trials to Start on Humans in the Next Five Years
Sources (just links for now until I actually cite them)
Summary of Cockroach Article
Article about Different Nanobot Structures
Actual Cockroach Article