Many types of nanomachines are designed to modify the biological structures for clinical, practical or cosmetic purposes. The nanomachines are carried into the body via a vector such as a geneered amoeba or bacteria. The machines and vector are typically delivered from a nasal spray and cross into the bloodstream through nasal membranes. Once in the body the nanos replicate relatively slowly (in comparison to industrial devices) over the course of several days, until they are present in great enough numbers to perform the task for which they were designed.
There are elaborate precautions taken to ensure that the nanomachines are only delivered to the intended recipient. The vector organism and the nanomachines are engineered so that initially they may only replicate in the presence of several proteins that do not occur naturally. These proteins are present within the solution in the delivery spray. When the concentration of the proteins falls below a certain level (i.e. when the solution has been diluted by nasal mucus and blood) the nanomachines invade cells and record stretches of RNA. The RNA is compared with the nanomachine's database until a rare sequence is found. The machine then modifies itself so that this nucleic acid strand is necessary for replication. This process renders the nanos almost uninfectious.
In the case of nanomachines intended to be active for only a limited period (for example to lay down the circuitry for a neural jack or to conduct other nanosurgery) the machines are not allowed to select an RNA sequence. Instead the patient is injected with the protein cocktail that allows replication. The proteins are engineered so that the body's antibodies will attack a subset of the active sites required for nanomachine replication, rendering them useless for the nanomachines. When the protein concentration falls below a certain threshold the nanomachines destroy themselves, disassembling into harmless compounds.
Nanomachines are used for many medical procedures including:
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