A group of researchers at the University of Washington has found a way to isolate and identify medically interesting molecules using little more than scraps of office paper, a Ziplock bag and a cheap diluted solvent. If properly developed, the system – which requires minimal costs and know-how to build and operate – could be made to administer a wide range of medical tests nearly free of charge.
Healthcare can come at a steep price: according to the American College of Physicians, the costs of unnecessary medical testing in the U.S. alone have soared to upwards of US$200 billion per annum – the grand total being much higher. With such a wide margin for improvement, a lot of research is going into putting a dent in this figure in an effort that could not only reduce expenses at home, but also do a great deal toward raising the standard of medical care in developing (or simply cash-strapped) countries.
One way to tackle the problem is to use cheap but effective materials, such as specially treated paper. Today, most paper-based diagnostics are made from nitrocellulose, a sticky membrane that can detect proteins, DNA or antibodies in the immune system and is used, among many other things, in home pregnancy tests.
Researchers at the University of Washington have worked out a way to replace nitrocellulose with much cheaper scraps of paper – the kind you would find in a typical office setting. When properly treated, the paper can detect a wide range of chemically interesting molecules (even more than nitrocellulose can) and could serve as a virtually zero-cost framework to build devices like home pregnancy tests that work for malaria, diabetes and other diseases.
The team filled a Ziplock bag with a 10 percent solution of divinyl sulfone – a cheap industrial solvent that is commonly used as an adhesive – and added a stack of paper. They then shook the mix for a couple of hours, extracted the paper from the bag, and let it out to dry.
When treated this way, the paper acquires a very interesting property: it normally feels smooth to the touch, but becomes sticky in the presence of chemicals that are of medical interest – proteins, antibodies and DNA, just like nitrocellulose, but also sugars and the small-molecule drugs used to treat most medical conditions.
To test their concept, the researchers printed an invisible pattern of galactose onto a treated scrap of paper. They then exposed the paper to fluorescent ricin, a poison that sticks to galactose, and detected that the poison was present in the exact same pattern in which the galactose had just been printed. This showed that the paper had indeed become sticky in the presence of a galactose, retaining it in place.
"We wanted to make the system as independent of the end applications as possible, something to not just ask a single question but many personal health questions,” assistant professor Daniel Ratner, the main author of the study, commented. “‘Is there protein in the urine? Is this person diabetic? Do they have malaria or influenza?'"
After producing this simple but effective framework, the researchers are hoping that other groups will build on their work to develop actual diagnostic tests in the near future.
A paper detailing the study was published in the journal Langmuir.
Source: University of Washington
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