Natural proteins can act like delivery vehicles to carry drugs directly to diseased cells. When a person takes a pill, the active ingredients in it spread throughout the body. While this is necessary for the drugs to reach the affected tissues and cells, it also means that healthy cells are often exposed to these substances, which can cause unintended side effects. In a recent study published in Nature Communications, a team of researchers from TU Darmstadt, led by professors Felix Hausch and Alexander Loewer, has discovered a way to use natural proteins in human cells to deliver drugs more precisely to the cells that need them most. The key to this method involves the development of small chemical compounds that can bind to disease-related proteins and link them to natural proteins found in the affected cells. This binding process helps block the disease-associated proteins and directs the therapeutic agents specifically to the diseased cells. Min Zheng, a chemist from TU Darmstadt's Structure-Based Drug Research Group, explained that the team used a method similar to assembling Lego blocks—called high-throughput conjugation chemistry—to identify these molecules efficiently. In addition to this targeted binding, the researchers discovered a phenomenon they call the "CellTrap effect." This effect allows active substances to accumulate in high concentrations within the cells, making the drugs more effective and enabling them to be directed specifically to diseased cells. Christian Meyners, a biochemist from the same group, noted that this principle is general and could be applied beyond the specific conditions of their study. To test this approach, the team used a drug that is toxic to cells and directed it specifically at prostate cancer cells. They took advantage of the fact that these cancer cells have higher levels of a protein called human FK506-binding protein 12 compared to healthy prostate cells. When both cancer and healthy cells were treated with the drug, only the cancer cells were affected, while the healthy cells remained unharmed. This finding highlights the potential of the CellTrap effect as a valuable tool in the development of more precise and effective therapies.