Think of Suzie Hwang Pun as a traffic cop for genes. The 27-year-old chemical engineer uses polymers tocarry injected genes through the bloodstream. With a system of molecular tags, she can direct a gene, for instance,one that blocks cancer progression, to just the right spot—like the nuclei of cells in a tumor. It is a trick that couldsolve a problem in gene therapy research: a new gene does no good if it does not reach the right place. Whileviruses are the typical delivery vehicles in gene therapy, they are hard to manufacture and can be intercepted bythe immune system. Pun’s polymer materials avoid those problems and open the possibility of delivering drugs, aswell as genes, with exquisite precision. “This is the tip of the iceberg,” says Caltech chemical engineer MarkDavis. He was so excited by Pun’s accomplishments as a graduate student in his lab that he founded InsertTherapeutics in Pasadena, Calif., primarily to commercialize her work. Pun jumped at the chance to be a seniorscientist and employee number one. If all goes well, her technology could enter human trials within a few years.