As a child Khine spent countless hours creating designs on Shrinky Dink plastic and watching them shrink in the oven. Years later she returned to her favorite toy out of necessity when, after joining a brand-new university, she lacked much-needed facilities for making microfluidics chips. The Shrinky Dink inspiration struck Khine one evening while spending time in her kitchen ("It's where I do most of my thinking," she says).
Khine knew that when Shrinky Dinks condense, any ink lines on the plastic become raised—and that's precisely what she sought in a microfluidics mold. She bought Shrinky Dink plastic designed for computer printer use, printed a pattern, and baked it for several minutes in her toaster oven. The results exceeded her expectations. Instead of just making molds, Khine ultimately developed a technique to make microfluidics chips directly from Shrinky Dink plastic. "It actually worked really well," Khine says, well enough to found a company based on that basic premise. To create products such as stem cell research devices and solar cells, Shrink Nanotechnologies has developed a new material that trumps the toy's abilities. Says Khine: "Shrinky Dinks shrink by 60 percent, but our new polymer shrinks 95 percent. And the properties shrink more consistently."
Balloon within a Balloon
One morning in 2002 Shiladitya Sengupta gazed out a train window and saw the solution to a vexing problem. He and other cancer treatment researchers wanted to transport chemotherapy drugs inside a tumor after blocking its blood supply. "It's almost like, how do you fill a bucket of water after the tap has been shut off?" says Sengupta, an assistant professor of medicine and health sciences and technology at Harvard Medical School in Boston.
His epiphany came after spotting a vendor who sold balloons inflated inside larger balloons. Sengupta realized the balloon-within-a-balloon structure could help him tackle the drug delivery challenge. He envisioned a bigger "balloon" that would burst and release drugs to shut off tumor blood vessels—then a smaller balloon would release chemotherapy drugs.
"I think people were surprised by the simplicity of the idea," he says.
Sengupta and his colleagues parlayed that balloon breakthrough into a new strategy for cancer treatment: a nanocell. "We called it a nanocell because it looks like a nucleus and surrounding lipid structure, but it's significantly smaller than a cell," Sengupta says. Measuring less than 200 nanometers, the nanocell contains different drugs in each of its two layers. In 2005 Nature published details of this particular drug delivery. (Scientific American is part of Nature Publishing Group.)
Sengupta later co-founded Cerulean Pharma, Inc., which focuses on nanotechnology-based treatments. Although its current products are based on single drugs, the company does hold a license to develop dual-drug nanocells. Other scientists have adopted Sengupta's balloon-within-a-balloon idea. A research group at Boston's Massachusetts General Hospital, led by Tayyaba Hasan, has used nanocells and photodynamic therapy (light-activated chemicals) to target pancreatic cancer. They presented the results of their work with mice in November 2009 at the Molecular Targets and Cancer Therapeutics conference. It is too soon to predict when human trials will begin for their nanocell treatment, says Hasan. "'As soon as we can' is the short answer."