How does Nanotechnology or Drugs in General find specific Target Areas?

laptoprabbit asked:


I’m wondering, for example, you take medicine for a painful kidney (this is just for instance). How does the medicine know exactly where to go? Let’s take this a step further and pretend we are dealing with nanotechnology. How would the nanos (basically, really small particles) know where to deposit the drugs to the kidney? Is there some sort of chemical reaction going on, and if so, how and what? Thanks, and please tell me the source. :)

Introduction to Nanotechnology