A common trope of science fiction is the depiction of nanobots, small robots moving in the body fixing wounds or healing diseases. Unfortunately, we will never be able to create these types of machines. The mechanisms inside a robot a few nanometers large will instantly melt together, while the small metallic arms and claws seen in science fiction would bend and stick to the surface of the particle.
They will help to detect health problems
A real life nanorobot will be several times larger than a nanoparticle, will have a simple shape, as a sphere or a rod, and will be covered with many active molecules, several times larger than its metallic core. Since, in real life, mechanical nanorobots cannot be larger than the size of a bacterium, it is impossible for them to heal diseases inside our body. However, they will help doctors to detect health problems or to deliver drugs to specific parts of the body.