Doctors want to kill cancer cells without hurting normal ones. This is a big challenge. Researchers at the University of Geneva built a tiny system made of synthetic DNA strands. The system can spot cancer cells and drop strong medicine right where it is needed.
Current targeted treatments, such as antibody‑drug conjugates, already send drugs straight to tumors. They help reduce side effects, but they have limits. Antibodies are big, so they cannot move easily inside a tumor, and they can carry only a small amount of drug.
Why DNA Can Help
DNA strands are much smaller than antibodies. This lets them travel through tumor tissue more freely. Scientists can also attach many different parts to a DNA strand, allowing the delivery of several drugs at once.
A Two‑Key Safety Lock
The new design uses several short DNA pieces. Some pieces stick to proteins that appear only on cancer cells. Another piece holds a toxic drug.
When a cell shows two specific cancer markers, the DNA pieces attach to both and join together. This starts a chain reaction that builds more DNA structures at that spot, releasing more medicine. If only one marker is present, nothing happens—just like a two‑factor password that needs both codes to work.
Lab Tests Show Strong Selectivity
In lab experiments, the system correctly identified cancer cells with the right marker pair and delivered a powerful drug. Healthy cells nearby stayed unharmed. The researchers also showed they could load several drugs at once, which may help stop cancer cells from becoming resistant.
Logic Like a Computer
The DNA system works with simple logic gates, similar to the “AND” rule in computers. The drug becomes active only when both cancer markers are detected, making the treatment very selective.
Future Smart Medicines
Scientists hope to add more complex logic, creating medicines that can make decisions inside the body. Such “smart” drugs could adapt to each patient’s unique biology, improve effectiveness, and cut side effects. They are meant to help doctors, not replace them, and could change how we treat many diseases.
The work was funded by the Swiss National Science Foundation and builds on earlier research from the NCCR Chemical Biology program.