Researchers in the Whitesides group at Harvard and at Diagnostics For All have recently published an article in Analytical Chemistry about their paper-based test for liver function. We heard a bit about these little devices last fall at the MF2.0 workshop, and then again in the winter when Carly blogged about the NYTimes article featuring them, but now we’re getting all of the exciting details.
These multiplexed tests detect three markers of liver function: total serum protein, and the enzymes alkaline phosphatase (ALP) and aspartate aminotransferase (AST). Just 15 µl of whole blood is applied to the top of the device, and it wicks through a plasma separation membrane to remove red blood cells before reaching the test zones on the bottom side. After the assay has developed, the color change of the test zones can be evaluated qualitatively by eye, or quantitatively using a cell phone or desktop scanner.
A diagram of the top and bottom sides of the liver fuction test before and after the assay is run (upon the addition of a drop of blood).
This was quite a thorough paper--they evaluated several different plasma separation membranes, generated calibration and limit-of-detection curved, confirmed that the test zones were not cross-reactive, and validated their results using real whole blood. You’ll have to read the paper for all of the results, but I’d definitely recommend it!
The article citation is: Vella S, Beattie P, Cademartiri R, et al. Measuring markers of liver function using a micropatterned paper device designed for blood from a fingerstick. Anal. Chem., 2012, 84(6), pp 2883-2891.