Manufacturers are always trying to find ways to make things better, faster, and cheaper. In a search to find new ways to make medical tests meet that criteria, a University of Washington, Seattle, bioengineer developed a way to make plain paper stick to medically interesting molecules that may be used to create diagnostic testing supplies.
Many current paper-based diagnostics are made from nitrocellulose, a membrane used in pregnancy tests and by medical researchers to detect proteins, DNA, or antibodies in the immune system.
But, says Daniel Ratner, an assistant professor of bioengineering, “We wanted to go for the simplest, cheapest starting material, and give it more capability.” Ratner hopes to replace that specialized membrane with cheaper plain paper, to be used for many types of medical testing.
The researchers used an inexpensive industrial solvent called divinyl sulfone that has long been used as an adhesive. His group found that they could dilute the chemical in water, control the acidity, then add paper, place the paper and solvent into a plastic bag, shake for a couple of hours, then rinse and let the paper dry. The dried paper is sticky to all kinds of chemicals that could be of medical interest: proteins, antibodies and DNA, as well as small-molecule drugs used to treat medical conditions.
To test their idea, the researchers ran the treated paper through an inkjet printer where the cartridge ink had been replaced with biomolecules, and printed the biomolecules onto the sticky paper in an invisible pattern. Exposing that paper to fluorescent ricin, a poison that sticks to galactose, showed the poison being present.
Now that they have proven their concept, Ratner said, they hope other groups will use the paper to develop actual diagnostic tests.