DNA testing is a now a common feature of hospital laboratories in helping diagnose diseased patients. The business of preparing samples, amplifying nucleic acid sequences, and detecting the presence of specific sequences of DNA requires trained staff, professional equipment, and careful meticulous work. Many hospitals around the world, therefore, lack these diagnostic capabilities. Now a new device developed thanks to the Diagnostics for All foundation and Harvard University promises to bring DNA testing to even the most remote and impoverished corners of the world.
The “Paper Machine,” as the researchers behind the project call it, is a microfluidic device made out of paper that costs about two dollars to produce. Without much training, a user can use it to prepare the liquid sample, perform loop-mediated isothermal amplification (LAMP) and finally shine ultraviolet light and use a smartphone to detect the presence of nucleic acid sequences pointing to disease. The device has a central sliding plate that is pulled by the user one notch after each step in the four-step testing process. This essentially automates the process of adding the sample, introducing the wash buffers, then the amplification master mix, followed by a stain dye once incubation is complete. A simple blacklight can then be used to illuminate the resulting sample, with a smartphone camera then spotting the presence of the dye.
From the study abstract:
Starting with human plasma spiked with whole, live E. coli cells, this paper demonstrates full integration of sample preparation with LAMP amplification and end point detection with a limit of detection of 5 cells. Further, it shows that the method used to prepare sample enables concentration of DNA from sample volumes commonly available from fingerstick blood draw.
Study in Analytical Chemistry: “Paper Machine” for Molecular Diagnostics…
Source: American Chemical Society…