If I mention medical nanorobotics, you might think of the designs put forward by Robert Freitas and others: molecular machines constructed largely from carbon that bear little relation to the cells and cellular system they are intended to interact with. Or you might think of the crude forerunners of those designs presently being tested in the laboratory, such as targeted nanoparticles and nanocontainers used to deliver drug compounds more precisely to where they are needed.
But you and I are built out of nanorobots: each of our cells is effectively a structured collection of cooperating, programmable nanoscale robots. They are evolved rather than designed, but still represent a vast preexisting parts library for researchers interested in building the first generation of medical nanorobots. While it is true that there are good reasons for reinventing this wheel, such as gaining far greater performance than is possible from anything similar to our present biology, given that time is of critical importance in developing the next generation of medicine, why not use these existing designs?
It seems likely that the first medical nanorobots (well, microrobots in this case) will be highly modified or even completely artificial cells. Why ignore the working blueprint that's right in front of you, after all?
Researchers are already building the prototypes, far more advanced than simple targeted nanoparticles. Here, for example, is news of progress towards nanofactories. These are programmable, artificial bacteria-like entities that can be set up to manufacture specific drug compounds in response to their local environment, or to signals from outside the body such as light or ingested chemicals.
Scientists are reporting an advance toward treating disease with minute capsules containing not drugs - but the DNA and other biological machinery for making the drug. ... development of nanoscale production units for protein-based drugs in the human body may provide a new approach for treating disease. These production units could be turned on when needed, producing medicines that cannot be taken orally or are toxic and would harm other parts of the body. Until now, researchers have only done this with live bacteria that were designed to make proteins at disease sites. But unlike bacterial systems, artificial ones are modular, and it is easier to modify them. That's why [this research group] developed an artificial, remotely activated nanoparticle system containing DNA and the other "parts" necessary to make proteins, which are the workhorses of the human cell and are often used as drugs.
They describe the nanoscale production units, which are tiny spheres encapsulating protein-making machinery like that found in living cells. The resulting nanoparticles produced active proteins on demand when the researchers shined a laser light on them. The nanoparticles even worked when they were injected into mice, which are stand-ins for humans in the laboratory, producing proteins when a laser was shone onto the animals.
The sky is the limit once biotechnology really takes off - and we're still in the early stages of this phase of progress. Much more is yet to come.