Nanite

Nanites are tiny robots (measured on the nanoscale; 1 nanometer is one billionth of a meter and ten millionth of a centimeter) that are used to manipulate matter on the molecular, atomic and even subatomic levels.

Nanites are used in the Deus Ex world for a variety of purposes, ranging from minor tasks, such as teeth-cleaning and locking doors, to complex purposes such as nano-augmentation. NanoKeys utilize nanites to lock objects such as lockers and doors. In Deus Ex: Invisible War, multitools use nanites to infiltrate locks.

One of the greatest creations of the 2050s is the Universal Constructor. Although nanites have been around for decades, modern UC's arrange them on arrays, allowing them to manipulate relatively large quantities of any substance on the subatomic level; essentially, whoever owns a UC is capable of creating virtually any physical entity desirable, so long as ample energy and coolant are provided, including living beings.

During nano augmentation, nanites freely flow through a human's bloodstream, and into organs, where they enhance the organ's capabilities (for example, through Microfibral Muscle, muscles are stimulated through nanites; through Aqualung, nanites in the respiratory system derive oxygen from water). Of course, nano augmentation is only possible if the recipient has an immune system that cooperates with nanites; nanites rejecting their hosts are responsible for the Gray Death plague in 2052 and the Cairo nanite plague in 2072. This "Nanite Accepting" DNA only occurs extremely rarely biologically, and it is usually only practical to clone human beings with genes tailored for nanotechnology. It is possible to completely rewrite an individual's genetic code so that they can accept augmentation, but this is an incredibly expensive, painful process that leaves physical scarring. Walton Simons and Bob Page were the first two humans to have their DNA rewritten in this way, but it left severe blue scars across Simons face and hands, and some sort of disturbance can be seen on the back of Page's head. DNA alteration has been perfected by 2072, and both Klara Sparks and Leo Jankowski are physical proof that the process can be not only possible, but practical too. ApostleCorp and Piezochem both unite to bring about truly universal augmentation through this method.

The Omar, a race of Russian scientists whom have so extensively augmented themselves that they are mostly artificial are encountered in Invisible War. Being an Omar comes with many benefits, such as having the most advanced augs possible, access to black-market Omar biomods, and biological immortality (Nanites will cull any undesirable organic cells and replace them with optimal ones, theoretically letting each individual Omar live indefinitely, in nearly any environment possible). At the same time, the Omar have several disadvantages: they all share a single consciousness, eliminating all free will and they are often treated with hostility by the public for their strange appearance (Especially with luddite groups like the Knights Templar). The Omar are incredibly reliant on their augs, so much that EMP attacks are capable of killing them.

At the beginning of Invisible War, a "Nanite detonator" is activated in Chicago, destroying the city and killing millions. This detonator apparently works by rapidly altering the surrounding environment in a growing radius with nanites, leaving the environment as some kind of inert substance; heavily resembling a theoretical grey goo scenario.

In the endgame, if the player chooses the ApostleCorp ending, nanites are used to distribute biomod infusions worldwide, making all humans "perfect" and giving them all instant communication with the Helios AI, in effect bringing about the first truly perfect democracy, albeit at the sacrifice of privacy.