Think of Suzie Hwang Pun as a traffic cop for genes. The chemical engineer uses polymers to carry injected genes through the bloodstream. With a system of molecular tags, she can direct a gene—say, one that blocks cancer progression—to just the right spot—like the nuclei of cells in a tumor. It’s a trick that could solve a huge problem in gene therapy research: a new gene does no good if it doesn’t make it to the right place. While viruses are the typical delivery vehicles in gene therapy, they’re hard to manufacture and can be intercepted by the immune system. Pun’s materials avoid those problems and open the possibility of delivering drugs, as well as genes, with exquisite precision. “This is the tip of the iceberg,” says Caltech chemical engineer Mark Davis. He was so excited by Pun’s accomplishments as a graduate student in his lab that he founded Insert Therapeutics in Pasadena, CA, primarily to commercialize her work. The clear-spoken Pun jumped at the chance to be a senior scientist and employee number one. If all goes well, her technology could enter human trials within a few years.