Paper Versus Pancreatitis

As the pursuit to develop more sophisticated and sensitive diagnostics continues, the cost of producing those tools and techniques tends to increase, making them inaccessible to low-and middle-income countries. But moving forward doesn’t always have to come with a hefty price tag, as researchers from the Indian Institute of Science have shown with their new paper-based biosensor, which uses photoluminescence to detect lipase (1).

Why is this biomarker important? High levels of lipase in blood can indicate pancreatic inflammation. A quick, affordable diagnostic could aid in the preliminary diagnosis of pancreatitis, especially in low-and middle-income countries (LMICs) that may lack conventional diagnostic equipment – or even the electricity to power it.

The apparatus consists of a paper disc embedded in a terbium gel that contains a pro-sensitizer (a chemical that liberates the sensitizer). It costs approximately one and a half cents to produce five discs, making it an extremely cost-effective technique.

How exactly does the biosensor work? “Upon activation of the specific enzymes, the 2,3-dihydroxynaphthalene sensitizer is liberated, resulted in the ‘turning-on’ of green luminescence, detectible under UV light,” says Uday Maitra, study author and Professor in the Department of Organic Chemistry at the Indian Institute of Science. “The main idea with this is to chemically modify the sensitizer with an enzyme-cleavable group. The advantage, we felt, was that as long as we are able to design appropriate pro-sensitizers, all enzymes will be detected with the same fluorescence.”

Indeed, the investigators have big plans for the ultra-cheap biosensor. “At present, we have half a dozen pro-sensitizers, and we are developing more artificial substrates to detect more enzymes. On top of that, we’re improving the sensitivity, and fabricating a handheld device that can be used for imaging and quantifying the enzyme-triggered luminescence of the paper discs. So a lot of work remains to be done!”