Robert S. Langer '70 began his career as a chemical engineer by getting turned down for a lot of jobs. "Mostly they just didn't write back," he said. Fortunately, that led him to realize that what he wanted to do was to use materials science and chemical engineering to help medicine.

After finishing his Sc.D. at the Massachusetts Institute of Technology, Langer began work with a Boston physician on what was then a radical idea: fight cancer with a drug that interferes with chemicals tumors secrete to grow new blood vessels to nourish themselves. Langer helped find these "angiogenesis inhibitors," but they couldn't be taken by mouth and quickly broke down when injected, so he developed a way to enclose them in porous polymer microspheres from which they would be released gradually. Today, 1.5 million people use angiogenesis inhibitors every year.

Continuing to work with polymers -- materials created by joining many small molecules together in complex chains -- Langer moved on to create other new drug-delivery systems, now used to treat diseases from cancer to schizophrenia. When nanotechnology arrived, he developed implantable microchips that could release drugs on command. Polymers also offered a way to build "scaffolding" on which living cells could build new tissues, from skin grafts to replacement blood vessels. In the near future such scaffolding might sculpt new noses, ears or livers, or even grow new nerves to repair spinal cord injuries.

In describing his work during a seminar Sept. 30, sponsored by the Cornell Department of Biomedical Engineering, Langer, the David H. Koch Institute Professor at MIT, sometimes seemed as much motivational speaker as researcher. His messages for a packed house of mostly students in G10 Biotech included:

• Just because they say it won't work -- as many grant reviewers told him -- don't believe it.

• Start with a picture of what you want to do and "synthesize a device from first principles."

• It's not enough to have a good idea; you also have to be an entrepreneur to get it out to the world. Langer holds more than 700 patents, licensed to 200 companies, some of them started by his former graduate students.

• You can't do it alone. Langer peppered his talk with the names of former students and post-doctoral researchers who worked on various developments, noting that each one had gone on to become a professor or CEO of a high-tech company. Among them is David Putnam, associate professor of biomedical engineering at Cornell.

Before delivering his talk, Langer, whose daughter is a Cornell freshman chemistry major -- "She turned down many top schools for Cornell," he noted -- spent a busy day visiting Cornell researchers in chemistry, nanotechnology, polymer chemistry and other related disciplines, many of whom are making important contributions to drug delivery, tissue engineering and other aspects of biomedicine. "I'm just delighted to see something we started long ago continuing to advance," he said.