INorthwestern’s Chad Mirkin and his team have re-engineered the common chemotherapy drug 5-fluorouracil (5-FU) into a spherical nucleic acid (SNA), making it up to 20,000 times more effective at killing cancer cells while reducing toxicity. In animal models of acute myeloid leukemia, the SNA drug targeted cancer cells 12.5 times more efficiently and halted disease progression without detectable side effects.