There are four ways for nanoparticles to enter the human body: inhalation, swallowing, absorption from the skin, or intentional injection (or release from implants) during medical procedures. Once in the human body, they have a high degree of mobility. In some cases, they can even cross the blood-brain barrier.
The behavior of nanoparticles in organs is still a big subject to be studied. Basically, the behavior of nanoparticles depends on their size, shape and interaction activity with surrounding tissues. They may cause an "overload" of phages (cells that swallow and destroy foreign substances), which can trigger defensive fever and reduce the body's immunity. They may accumulate in organs because they cannot degrade or degrade slowly. Another concern is the potential danger of their reaction with some biological processes in the human body. Due to the large surface area, nanoparticles exposed to tissues and liquids will immediately adsorb the macromolecules they encounter. This will affect, for example, the adjustment mechanism of enzymes and other proteins.