An all-purpose disease-fighting nanomachine might take the form of a miniature submarine that would navigate its way through the bloodstream. In that submarine would be a powerful nanocomputer. This computer would be programmed to seek out and destroy disease-causing organisms. Sensor devices attached to the submarine would examine all objects it encountered, studying their shapes and surface molecules, and comparing them with a database of known disease organisms stored in the computer's memory banks. When a pathogen is encountered, it could be destroyed, broken down into its molecular building blocks.
The original caption for this image reads: "A molecular surgeon's knife at work. Painless and worry-free."