A snapshot of ongoing work to develop cost-effective tools for building targeted cancer therapies: "Scientists have spent more than a decade trying to direct liposomes to specific cancer cells, with limited success. A common approach involves attaching an antibody to the liposome membrane. Ideally the antibody will bind to a cancer cell receptor so that it can deliver the liposome - and the cancer drug - into the cell. Developing such antibodies is costly and time-consuming, however, and the process of attaching them to liposomes is difficult to control. ... Aptamers are short strands of DNA or RNA; they are highly efficient binders, and are very easy to make, label and manipulate ... [researchers] used an aptamer that binds to nucleolin receptors, which are found in abundance on certain breast cancer cells. The researchers then developed an effective method for attaching the aptamer to a liposome loaded with cisplatin, a drug that effectively kills cancer cells but has troublesome side effects when administered intravenously. Tests in cells grown in the lab yielded promising results. Four days after they exposed the cells to the new drug-delivery system, 59.5 percent of the breast cancer cells had died, while less than 12 percent of breast cancer cells treated with cisplatin alone had died. ... Another advantage of using aptamers as targeting agents is that they are easily disabled. They readily bind to complementary DNA, which prevents them from interacting with cell receptors."