California Institute of Technology scientsits have created molecular biocomputers that self-assemble using strips of RNA within living cells, opening up the possibility of computing devices that can respond to specific conditions within the cell.

For example, drug delivery systems could target cancer cells from within by sensing the genes used to regulate cell growth and death, programmed to release a drug when the conditions are just right.

The biocomputers are built from sensors, actuators, and transmitters–all made up of RNA. The input sensors are made from aptamers (RNA molecules that behave a bit like antibodies, binding tightly to specific targets); the output components, or actuators, are made of ribozymes (complex RNA molecules that have catalytic properties similar to those of enzymes); and another RNA molecule that serves as a transmitter, which is activated when a sensor molecule recognizes an input chemical and, in turn, triggers an actuator molecule.