Nanites are self-sufficient nano-robotic machines that are capable of receiving information and directives from both outside and inside the human body.
How we do it?
Owing to the direct control aspect, nanites are instructed to target specific cell types and destroy them. This means look for cancer cells and kill them same with other viruses and foreigners in your body.
How do we charge it?
In previous versions the use of solar power was required to charge them up before entering the body. Now, these wonders utilize blood and the neurological electricity from you body for power!