I'm surprised this hasn't been posted before, but here's the description of nanomeds that was on the official website for The Hulk: The nanomeds, which are essentially little molecular machines, remain inert in the body until we activate them with a burst of gamma radiation. Then they instantly go to work repairing tissues, by breaking down damaged cells, and by forging healthy cells to replicate. The problem we've been having involves managing the energy flux created by such rapid cellular activity and buildup of waste products from the dismantled cells. Which have so far led to catastrophic results. In our next round of experiments, we'll be damaging the cells with drastically higher doses of gamma radiation, resulting in more uniform trauma. We hope in this way to better contain their destructive potential. If we succede we may someday realize of near-instantaneous bodily repair. Death is a kind of forgetting. Each time a human cell replicates, it loses a loses a little more DNA from the end of its chromosome. Eventually it loses so much that it forgets its function. Its ability to cope with trauma and its ability to reproduce. Whereas life is the ability to both retrieve and act on memory. What makes the nanomeds so extraordinary is that they are life unbound. Part of life is death, forgetting and unchecked, mutations. The nanomeds remember their instructions to well. Basically to stay alive we must forget as much as we remember. Nanomachines Nanomachines are actual mechanical devices built on an incredibly tiny scale. Like ordinary machines, nanomachines comprise levers, gears, pistons and other familiar mechanical components; but instead of components constructed from wood, plastic metal on a scale of inches or feet, nanomachines are assembled directly from individual atoms. So these are unimaginably small machines: in the case of my nanomeds, they are quite a bit smaller than a human cell. Nanomachines are no more alive than a photocopier or an electric can opener - they're machines. However, some nanomachines (like my nanomeds) are designed to reproduce themselves, which according to some schools of thought is one of several criteria for life. The intent of my research is that the nanomeds float around harmlessly inside a human body until they detect tissue damage; then they respond in one of the ways the human itself does: they copy cells to replace the damaged ones. And while it might seem unnecessary to build a machine to artificially mimic a function already addressed by natural processes, the point is that sometimes an organism's own cellular replication can't proceed fast enough or thoroughly enough to be effective - in the case of a rapidly spreading infection, for example, or massive tissue trauma. But my nanomeds can, at least in theory; thats the goal of my research. Nanomeds and Human Testing Nanomeds should not be tested on humans yet. They're still experimental enough that human testing is unthinkably risky. Up to the present, they have been very successfully applied to microscopic tissue samples sitting in a Petri dish, and just recently the team has proceeded to using small organisms, like frogs. At the current rate of progress, it would still be many years before the nanomeds could conceivably be tested in human beings. Nanomed Operations Nanomeds placed in an organism remain ready but inert until they detect cell damage, which triggers two kinds of activity: the disassembly of damaged or infected cells, and the replication of good cells from the same region to replace the destroyed ones. Disassembly is necessary because the old cells are presumed to be no longer functioning - they've been corrupted or infected or incapacitated: they're useless at the very least, and actually hazardous in many common cases. Even if they weren't, it would be inadvisable to allow them to remain because the overall number of cells must stay the same. Otherwise the organism becomes bigger. Cells under stress release various kinds of chemical alarms, a very common example being one of the naturally occurring 'interferon' proteins. So my nanomeds are treated (prior to injection into the organism) with a chemical factor called BR-1 that binds to the nanomed and helps it recognize interferon and other cellular distress signals. BR-1 is like a pilot placed in a nanomeds 'cockpit' to aim it to the necessary site, or like letting a bloodhound sniff a scrap of cloth with some scent in it to get it to track down whatever made that scent. BR-1 is the result of a long and very challenging development project of its own, led by Dr. Ross, but the factor in use by my team in 2003 is entirely reliable and has precisely the right properties. Nanomeds and the Absence of BR-1 Without BR-1 the nanomed wouldn't know what to replicate and what not to replicate, so that it could end up copying things that might not be particularly beneficial: invading bacteria, viruses inside the organism. It's also possible that under such pilot-less circumstances the nanomeds could replicate inorganic matter, things that aren't cells. Nanomeds and Cellular Replication/Destruction My team and I have experimented with both orders (replicate first, destroy first); at the moment we're assuming that it's better to dismantle the old cell before making a new one, so that there's no possible way to copy the bad one by mistake. Whatever that turns out to be true or not, this aspect of the nanomed design is an extremely tricky balance and remains the last major research hurdle: most of my team's current efforts are aimed at solving this. The balance itself is established and controlled by another chemical factor called BR-2. The research team has been trying a whole spectrum of such factors (BR-2/A: copy first, then dismantle; BR-2/B: dismantle first, then copy; BR-2/W: dismantle and wait a little while before copying; BR2/WW: wait a long while before copying; and so on). 'BR' stands for the developer of these chemical factors: Betty Ross. The Purpose of the BR-2 Spectrum The purpose of the BR-2 is to react to an organism's current level of chemical 'distress signals' (interferon, etc.) by adjusting the ratio of copying activity to dismantling activity. When that ratio is correctly adjusted, equilibrium is reached in which the same number of cells is being created as are being destroyed. But if the BR-2 induces an incorrect ratio, then the nanomeds copy too much or dismantle too much - and in the extreme, where theyre only copying or dismantling, the organism ends up either exploding or melting. 'Copy-Only' Nanomeds Copy-only activity in nanomeds is impractical, because the resulting pressure - suddenly adding lots of cells to an organism (i.e. extra material squeezed into the same space) creates a large internal pressure, and the structure of most complex organisms, especially mammals, is such that they cannot withstand such stresses. Nanomed Reproduction It's necessary to adjust the number of nanomeds working according to how much work there is to be done, since the particular goal of my research is to use them to heal fast enough to save an organism's life. So when there's nothing to do, relatively few nanomeds are floating around. If there's a little bit of trouble, nanomeds near the damaged site go work, but they also spend a fraction of their time reproducing, so that there are enough of them to complete the repair work efficiently; and if there's widespread damage (like high-level radiation exposure), then vastly larger numbers are required - so they have to be good at making more of themselves. After a massive healing effort is completed, the nanomeds slowly get broken down and reabsorbed by the organism itself. Naturally, they always insure that there's a minimum concentration of them present so that they're available as soon as there's a new alert. It should be noted that a mass of nanomeds is never completely at rest - there's inevitably some small amount of bacteria and virus scattered around inside every organism, trying to get a foothold. Basically there's always a little bit of copy-and-dismantle activity going on. Gamma Radiation and Nanomed Research Gamma radiation is one of the most important safety measures employed by my team. During our years of research, while the nanomeds are still experimental, the team has to make sure that there's no chance of human 'infection.' One safety measure is part of the specific design of the nanomeds themselves: they are constructed so that they cannot exist in air - if my nanomeds are not in a liquid environment they break apart immediately into smaller, harmless molecules. This removes the risk of a nanomed population drifting in the environment and infecting a researcher who happens to breathe them in. As concerns the gamma radiation, the nanomeds are deliberately manufactured in a dormant state in which they are entirely inactive - even if some were accidentally introduced into a human body, they'd float around doing nothing in their inert state until eventually they got broken down and absorbed by that body's natural metabolic processes. The point is that the nanobots cannot begin doing anything unless they've been triggered explicitly. My team chose an activation mechanism involving gamma radiation as a way of guarding against accidental triggering: gamma rays always have to be manufactured deliberately; they don't occur naturally on Earth's surface in nearly high enough doses. Nanomed Trigger Mechanisms Strictly speaking, the nanomeds don't respond to the gamma rays directly, but rather to the biological results of gamma ray exposure: a characteristic level ionized, electrically charged organic molecules. It's this ionization that the nanomeds respond to.