Testing for Disease, for Under a Penny, Using Bits of Paper
While other scientists successfully shrank beakers, tubes and centrifuges into diagnostic laboratories that fit into aluminum boxes that cost $50,000, George Whitesides had smaller dreams.
BIG DEAL A nonprofit company produces diagnostic tests the size of a stamp.
The diagnostic tests designed in Dr. Whitesides’s Harvard University chemistry laboratory fit on a postage stamp and cost less than a penny.
His secret? Paper.
His colleagues miniaturized diagnostic tests so they could move into the field with tiny pumps and thread-thin tubes. Dr. Whitesides opted for a more novel approach, reasoning that a drop of blood or urine could wick its way through a square of filter paper without any help.
And if the paper could be etched with tiny channels so that the drop followed a path, and if that path were mined with dried proteins and chemically triggered dyes, the thumbnail-size square could be a mini-laboratory — one that could be run off by the thousands on a Xerox machine.
Diagnostics for All, the private company Dr. Whitesides founded four years ago here in Boston’s Brighton neighborhood to commercialize his inspirations, has already created such a test for liver damage.
It requires a single drop of blood, takes 15 minutes and can be read by an untrained eye: If a round spot the size of a sesame seed on the paper changes to pink from purple, the patient is probably in danger.
Using paper in diagnostic tests is not entirely new. It soaks up urine in home pregnancy kits and blood in home diabetes kits. But Dr. Whitesides has patented ways to control the flow through multiple layers for ever-more-complex diagnoses. His test has proved more than 90 percent accurate on blood samples previously screened by the laboratory of Beth Israel Deaconess Medical Center, a Harvard teaching hospital, said Una S. Ryan, chief executive of Diagnostics for All.
“They should be even more accurate on fresh blood,” added Dr. Ryan, a biologist. Field tests in India are set for later this year.