"Blood Music," by Greg Bear

This was a great story. I think I read it a long time ago. I am not sure but it seemed familiar. I know it is a classic. The science in it is fascinating. Greg Bear always makes his science fiction read just like it is real science and so possible it is happening. He tells the tale of a scientst gone bad, one who ultimately experiements on himself like so many others, but this time he has injected himself with what we would call today nanomachines. Each has been programmed to improve him and change him for the better. He loses weight, he looks better, his back doesn't hurt, but all these are at the cost of being human. His spine, his heart and other internal organs and everything about him has changed and then they eventually communicate with him and take over. A friend, who is a doctor, tries to stop it all by killing him while he takes a bath, but the doctor and his wife become infected and the end suggests that these nanomachines are loose and will change the world. It is a great story.