chemical receptors. Intelligent design may mitigate the need for such receptors. Since all mid-size objects put into the body tend to congregate in the liver, an appropriately sized nanofactory—about 100 nanometers in diameter—will be drawn to the right place without any sensors. The tyrosine product would exit into the patient’s blood stream, preventing a profound irreversible mental disease.

This pared down factory, proposed by the group, may require input and output sensors to serve as door-keys, but a molecular understanding of the nature of the disorder must be mastered for their design. While this gap in knowledge is not a general scientific failure, it was, unfortunately, not available within the expertise in the group. It points to a larger gap, though, for the expansion of this technology for other diseases: the metabolic pathways and basic biochemistry of the problem must be understood before a factory can be built to fill in for the body’s malfunction.

The design for the nanofactory laid out by the group can be modified for the production of hormones like thyroxine to manage thyroid disorder; growth factors, such as tumor necrosis factor-α (TNFα), to specifically target and kill cancerous tumors; and insulin precursors that could be produced and self regulated to relieve diabetes sufferers of daily injections. Nanofactories could also be used to withdraw unwanted materials from a biological environment—toxic chemicals resulting from a drug overdose or excess LDLs (low density lipoproteins), famous for their link to heart disease. Each of these conditions would require a complex multi-enzyme assembly line to produce the biomedically useful product.

The nanofactory blueprints developed by the group have the potential to revolutionize individualized medicine. Instead of taking daily doses of drugs, which are mostly excreted before they are absorbed and can cause nasty side effects, injections of medicinal nanofactories have the potential to offer selective, regulated, time-sensitive therapy to produce and deliver the medicine your body needs exactly when and where your body needs it.

While the factory blueprints can be drawn up without much further effort, as the biochemistry and engineering knowledge already exists, there are some gaps that must be bridged before the nanofactories can be mobilized to treat disease. The most difficult challenges to overcome will be disease specific, as the construction of the nanofactory will vary based on its desired function. Designing a vesicle to safely contain particular enzymes