DNA has been used by researchers to develop a tool that detects and reacts to chemical changes caused by cancer cells and that may one day be used to deliver drugs to tumor cells. The researchers’ nanosensor measures pH variations at the nanoscale — how acidic or alkaline it is. Many biomolecules, such as enzymes and proteins, are strongly regulated by small pH changes. These changes affect in turn biological activities such as enzyme catalysis, protein assembly, membrane function and cell death. There is also a strong relation between cancer and pH.