The success of DNA nanotechnology in constructing artificially designed nanostructures out of nucleic acids such as DNA, combined with the demonstration of systems for DNA computing, has led to speculation that artificial nucleic acid nanodevices can be used to target drug delivery based upon directly sensing its environment.  These methods make use of DNA solely as a structural material and a chemical, and do not make use of its biological role as the carrier of genetic information.  Nucleic acid logic circuits that could potentially be used as the core of a system that releases a drug only in response to a stimulus such as a specific mRNA have been demonstrated. In addition, a DNA "box" with a controllable lid has been synthesized using the DNA origami method.  This structure could encapsulate a drug in its closed state, and open to release it only in response to a desired stimulus.