Nanobots exist in primitive forms as of 2015, but work is underway to develop machines that can function at the atomic level to sense their surroundings and react to their environments with a set of pre-programmed instructions, such as delivering a payload of cancer-killing drugs, clearing clogged arteries or repairing damaged tissue. Nanobots are also expected to help build better electronics and consumer products, improve communications and provide energy solutions.
One anticipated use of nanobots is to build more advanced nanomachines to perform these functions. Scientists recently injected cockroaches with nanobots in the form of strands of DNA that are programmed to unfold and release a molecule when they encounter a particular protein. Research is currently underway to treat humans with leukemia by injecting them with DNA nanobots programmed to recognize cancer cells by their surface proteins and release a dose of nanoparticles that cause the cancer cells to self-destruct.
Similar experiments using DNA-coated particles to kill the Hepatitis C virus by interfering with its replication process have been successful in laboratory tests. Researchers have also used nanobots to deliver medicine in live mice. The nanobots were coated with a chemical that reacted with digestive juices to propel them into the walls of the stomach where they dissolved and released the medicine. The mice experienced no other harmful effects.
There are a number of problems, such as getting the nanonbots to the right location and producing them in sufficient quantities, that researchers must solve before medicinal nanobots become a reality.