Plain paper transformed into diagnostic tool

A team of researchers from the University of Washington (UW) has developed a way to make paper-based diagnostics using plain paper, by making the regular paper found at office supply stores stick to medically interesting molecules.

“We wanted to go for the simplest, cheapest starting material, and give it more capability,” said Daniel Ratner, a UW assistant professor of bioengineering and lead author of the paper. “We also wanted to make the system as independent of the end applications as possible, something any researcher could plug into.”

The UW team used a divinyl sulfone, a cheap industrial solvent used as an adhesive, diluting it in water and controlling its acidity. A stack of paper was then soaked in the solution inside a Ziploc bag for a couple of hours, before rinsing the paper and letting it dry. The dried paper is sticky to medically important molecules, such as proteins, antibodies, and DNA, as well as sugars and small-molecule drugs used to treat most medical conditions.

The paper was tested by using an inkjet printer to “print” galactose molecules onto the sticky paper in an invisible pattern. Exposure of the paper to fluorescent ricin, which sticks to galactose, demonstrated that galactose was present as predicted.