Take any piece of paper and have it diagnose your medical problem. That’s the kind of future that a researcher at the University of Washington (UW) can have us all living in soon.
The bioengineer at the university produced a chemical gimmick that makes regular paper grab onto certain medically indicative molecules. The diagnostic indicators can be made from plain paper, the kind found at the office supply stores, reports Laboratory Equipment.
“We wanted to go for the simplest, cheapest starting material and give it more capability,” says Daniel Ratner, a UW assistant professor of bioengineering and lead author of the paper recently published in the American Chemical Society journal Langmuir. “We also wanted to make the system as independent of the end applications as possible, something any researcher could plug into.”
Nitrocellulose, a sticky membrane used in pregnancy tests and by medical researchers to detect proteins, DNA, or antibodies in the human immune system, is the substance of choice for many paper-based diagnostics. But Ratner thinks that specialized nitrocellulose can be replaced by cheap, ubiquitous paper and used for any type of medical test, not just those that need to detect large molecules.
The UW technique is simple and uses common products. They took an industrial solvent, divinyl sulfone, an inexpensive industrial solvent that has been used for decades as an adhesive, and carefully diluted it with water, but controlling the acidity. Then they poured that mixture into Ziploc bags and added a stack of paper. After letting the stack sit for a couple of hours, they took the paper out and let it dry.
The dried paper is smooth to the touch but it is sticky to medically relevant molecules. Not only do proteins, antibodies, and DNA stick to the paper, but also sugars and small-molecule drugs used to treat most medical conditions.
“We want to develop something to not just ask a single question but ask many personal health questions,” Ratner says. “‘Is there protein in the urine? Is this person diabetic? Do they have malaria or influenza?”
To see how well the paper worked according to design, the UW researchers loaded the paper into an inkjet printer that had its cartridge ink replaced with biomolecules, specifically a small sugar called galactose that sticks to human cells. The biomolecules had been placed onto the paper in an invisible pattern. When that paper was exposed to fluorescent ricin, a poison that sticks to galactose, the pattern became visible, indicating that the paper can alert that the poison is present.
Ratner believes that their tests have proven that their concept is accurate. They hope now that other groups will pick up where he left off and develop actual diagnostic tests.
Source: “Chemical Method Turns Any Paper into Diagnostic Test,” Laboratory Equipment, 10/4/12
Image by Jonathan Joseph Bondhus.